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Chapter 8

Contents

CHAPTER VIII

New Hebrides, Solomon Islands, Saint Matthias Group, and Ryukyu Islands

Paul A. Harper, M.D., Wilbur C. Downs, M.D., Paul W. Oman, Ph. D., and Norman D. Levine, Ph. D.

A review of the experiences with malaria control of the USAFISPA (U.S. Army Forces in the South Pacific Area) may logically be divided into two parts: The first, dealing with the problem of malaria and other insect-borne diseases on those South Sea Islands which lay within the jurisdiction of the wartime command known as the South Pacific Area; the second, dealing with similar problems on Okinawa and other islands which were the responsibility of the Ryukyu Islands Command. 1

The military campaigns in both these areas were a series of amphibious operations which called for the closest cooperation between land, sea, and air forces. The antimalaria organization in both areas was also a joint Army, Navy, and Allied operation under centralized control. This report is concerned primarily with the malaria control activities of Army personnel, but it is emphasized that much of the success of the organization was due to its joint service nature which was the concept of the first theater malaria and epidemic disease control officer in the South Pacific, Comdr. (later Capt.) James J. Sapero, MC, USN, 2 and of his successor, Comd. F. A. Butler, MC, USN. 3

1 Unless otherwise indicated, Part I of this chapter is based on the material from a series of papers published in a supplement to the American Journal of Tropical Medicine, May 1947, on "Malaria and Other Insect-Borne Diseases in the South Pacific Campaign, 1942-1945." Appreciation is expressed to the editor and publisher of this journal for permission to utilize this material.
    Appreciation is also expressed to Brig. Gen. Earl Maxwell, U.S. Army, Surgeon, U.S. Army Forces in South Pacific Areas, and subsequently Surgeon, Ryukyu Islands command: to Capt. Arthur H. Dearing, MC, USN, Force Medical Officer, South Pacific Area; to his successor, Capt. Frederick R. Hook, USN; and to Brig. J. W. Twhigg, Director of Medical Services, New Zealand Expeditionary Forces, Pacific. These officers gave their constant support to the Malaria and Epidemic Control Organization and its work as described in this chapter.
2 (1) Sapero, J. J., and Butler, F. A.: Highlights on Epidemic Diseases Occurring in Military Forces in the Early Phases of the War in the South Pacific. J.A.M.A. 127: 502-506, March 1945. (2)Sapero, J. J.: The Malaria Problem Today; Influence of Wartime Experience and Research. J.A.M.A.. 132: 623-627, November 1946. (3) Sapero, J. J. : Tropical Diseases in Veterans of World War II. New England J. Med. 235: 843-846, December 1946. (4) Sapero, J. J.: Tropical Diseases as a Cause of Manpower Loss in Military Operations. Mil. Surgeon 106 : 111-114, February 1950. (5) Sapero, J. J. : Prevention of Malaria Infections by Drug Prophylaxis.  In Malariology, edited by Mark F. Boyd. Vol. II, pp. 1114-1132. Philadelphia: W. B. Saunders Co., 1949.
3 (1) Butler, F. A.: Malaria Control Program on a South Pacific Base, U.S. Nav. M. Bull. 41: 1603-1612, November 1943. (2) Butler, F. A., and Sapero, J. J.: Postwar Tropical Disease Problems in the United States. South. Med. J. 38: 459-465, July 1945. (3) Butler, F. A., and Sapero, J. J.: Pacific Vivax Malaria in the American Negro. Am. J. Trop. Med. 27: 111-115, March 1947.


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Subsequently, Captain Sapero occupied a similar position on the staff of Commander in Chief, Pacific, during the campaign for the Ryukyu Islands.

The reason for having one group of authors report about malaria control in such widely separated places is that members of this group, together with their Navy colleagues, participated in the planning and execution of insect control programs in both areas, first in the South Pacific and later on in the Ryukyu Islands, which was the scene of the last severe land fighting of the war.

Part I. New Hebrides, Solomon Islands, and Saint Matthias Group

GENERAL CONSIDERATIONS

Malaria problem, 1942-45. - Malaria was the single most serious health hazard to Allied troops in the South Pacific Area during World War II; it caused more than five times as many casualties as did combat. It is estimated that more than 100,000 individuals among Allied military personnel contracted malaria in the South Pacific, most of whom had several attacks. At least, on Guadalcanal, Solomon Islands, this disease threatened the success of the military campaign.

The first outbreak of malaria occurred on the small island of Efate in the New Hebrides, where it reached epidemic proportions with a rate of nearly 2,700 cases per 1,000 troops per annum in April 1942. The most serious epidemic of this disease began on Guadalcanal within 3 months of the initial landings. Lesser outbreaks occurred on Espíritu Santo, Tulagi-Florida Islands, the Russell Islands, and Munda, New Georgia. No serious outbreaks occurred on Treasury, Bougainville, Green, or Emirau Islands, which were the last four bases to be occupied and which were the scene of intense anti-malaria measures from the time of the initial landings.

In the early days of the South Pacific campaign, it was considered good medical practice to give therapeutic doses of Atabrine (quinacrine hydrochloride) or quinine to heavily seeded troops after removal from malarious areas and then to stop suppressive medication and treat the remaining malaria as it occurred. This process was called demalarialization and was based on the thesis that if troops were first treated with therapeutic doses and then allowed to have their malaria relapses they would develop an immunity and so overcome the disease. This regimen was undertaken by the 2d Marine Division, the Americal Division, the 147th Infantry, and other troops who had been on Guadalcanal during the malaria epidemic. It resulted in an enormous amount of malaria before it was abandoned in favor of continuous suppressive therapy for heavily seeded troops. The rehabilitation period of units who were subject to this procedure was approximately double the time estimated for this purpose and meant a serious decrease in the number of available combat troops.


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Malaria was serious enough for the Allies, but it was far worse for the Japanese; the few prisoners taken were almost invariably malarious. For example, 9,000 Japanese died of disease--malaria, malnutrition, beriberi, and dysentery--on Guadalcanal; 4 this was nearly one-half of all their dead on this island.

Other insect-borne diseases which occupied the attention of the antimalaria organization were dengue fever, filariasis, and tsutsugamushi disease. The importance of dengue tended to be obscured by the deluge of malaria; actually, dengue could and did cripple a military force for short periods more rapidly and more effectively than did malaria. Filariasis also led to the medical evacuation of many thousands of troops. Rodent control was undertaken to prevent the spread of epidemic diseases which were harbored by rats or their ectoparasites as well as to prevent the economic loss by large rat populations. The control of all these arthropodborne diseases became the responsibility of the South Pacific Malaria and Insect Control Organization.

Antimalaria organization .- The South Pacific Malaria and Insect Control Organization5 was developed to meet the peculiar needs of a mixed Army-Navy-Marine-New Zealand combat force engaged in a series of amphibious operations on 11 malarious islands scattered over many thousands of square miles of ocean (maps 23 and 24). This organization had several unusual features which were important to its success and which are briefly noted, as follows:

1. The mixed service character greatly facilitated the best utilization of scarce technical personnel and aided the supply problem by making it easier to draw available supplies from all services and to distribute them as needed.

2. The chain of command was unusual for a medical organization in that the senior malariologist (Navy) was on the staff of ComSoPac (Commander, South Pacific) and in that on each base the reports and recommendations of the senior base malariologist were submitted directly to the island commanders with copies to subordinate service commands.

3. Malaria control headquarters were established at the theater level and on each large base, although there was no table of organization and equipment for such groups. The theater malariologist and his staff were responsible for recommending assignment of scarce personnel and for establishing uniform policies regarding control measures and supplies.

4. The last unusual feature was the amount of autonomy and initiative allowed to the local malaria control groups on each island base.

Malaria control activities. - From the very beginning of planned malaria control in the South Pacific Area, the approach was primarily one of control of the mosquitoes responsible for transmission, with suppressive medication

4 Miller, John: Guadalcanal: The First Offensive. United States Army in World War II. The War in the Pacific. Washington : U.S. Government Printing Office, 1949.
5 This organization was first known as "South Pacific Malaria Control," and later as "South Pacific Malaria and Epidemic Control."


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MAP 23.- Pacific Ocean Area.

as a secondary insurance factor. The exact sequence in which measures directed against mosquitoes could be applied depended upon such factors as supplies, manpower, and authority to undertake the work; once these problems were solved, the mosquito was attacked with all these weapons in combined offensive.

The basic control measure, and that usually first initiated, was larval control by larvicides. Until mid-1944, the chief larvicide was diesel oil, applied by knapsack-type sprayers and vehicle-mounted power sprayers. After the advent of DDT, which became generally available about July 1944, airplane spraying was utilized effectively for elimination of larval populations. Coupled with the larvicidal program was a systematic program of reduction of water surfaces through drainage, road-rut elimination, stream cleaning, and installation of flumes to permit fluctuation of water level in lagoons along the beaches. Through these two general methods, the control of anopheline breeding became highly effective.

The control of adult populations of Anopheles was at first limited to spraying with petroleum base insecticides by hand-operated "flit guns," by the use of Aerosol bombs, and by barriers, such as bed nets and screens. Head nets were never widely used, nor were repellents, and the degree of


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MAP 24.- Malarious islands of the South Pacific Area


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malaria control attained by these means is considered negligible. During the latter half of the war in the South Pacific, DDT was widely used as a residual spray in living quarters, messhalls, latrines, and native quarters.

The systematic indoctrination of troops in the principles and practices of malaria control was, in the final analysis, probably as important an undertaking as any phase of malaria control. This training not only made possible a great extension of mosquito control activities but also paid dividends in the observance of personal protective measures, which at first were completely ignored. The success of the malaria control activities resulted from the multiple-faceted approach to the problem by many individuals.

MILITARY DEVELOPMENT

Mission

The Allied Armed Forces in the Pacific area were ordered on 2 July 1942 by the U.S. Joint Chiefs of Staff 6 to mount a limited offensive to stop the southward advance of the Japanese toward the sealanes between the United States, New Zealand, and Australia. The immediate objective was to obtain control of the Guadalcanal-Tulagi area where the Japanese were beginning the construction of an airfield (Guadalcanal) and had established a seaplane base (Tulagi). The ultimate objective of Allied war effort in this area for the next 2 years was to be the capture or neutralization of Rabaul as a Japanese stronghold.

It is to be recalled that the Allies had agreed to make their first major effort in Europe against Germany; meanwhile, the operation against Japan had to take a secondary place and was limited by the ships, troops, and supplies which could be spared. Furthermore, the initial surprise achieved by the Japanese gave them an extraordinary advantage which in less than 12 months of war enabled them to overrun and control a huge area of land and ocean. This area, with Japan as the hub, swung in a great southwestward arc from the western Aleutians through Guadalcanal to the southern tip of New Guinea and thence through the East Indies to the mainland of Asia. The Allies and particularly the United States were unready in many ways for this onslaught. Our lack of preparedness to handle the malaria problem and our failure even to realize how important malaria would become were symptomatic of the more general unreadiness.

The division of responsibility for operations in the Pacific is shown in map 23. The South Pacific Area was commanded first by Vice Adm. Robert L. Ghormley and, subsequently, by Adm. William F. Halsey, Jr.; they were responsible to Adm. Chester W. Nimitz, the Commander of the Pacific Ocean Areas. The Southwest Pacific Area was under the command of Gen. Douglas MacArthur.

6 See footnote 3, p. 401


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The South Pacific Area and Force was eventually given responsibility for land operations throughout the Solomon Islands and the Saint Matthias Group. Its area of authority was extended by successive orders and attained its maximum extent as shown in map 24.

Chronological Table of Operations

Early in the War, Allied naval, land, and air forces were gathered as rapidly as possible in the major nonmalarious bases--Samoa Islands, New Zealand, Fiji Islands, and New Caledonia. Theater headquarters were first established in New Zealand and later were moved to New Caledonia. Subsequent land operations were on malarious islands in the New Hebrides, Solomon Islands, and Saint Matthias groups. The chronological table for occupation of malarious bases was as follows:

Unopposed landings in New Hebrides:
    Efate - advance group landed, 18 March 1942.
    Espí ritu Santo- 4 May 1942.

Assault landings in Solomon Islands and Saint Matthias Group:
    Guadalcanal - 7 August 1942. Island secured, 9 February 1943.
    Tulagi and adjacent island - 7 August 1942. Secured, 9 August 1942.
    Russell Islands - 21 February 1943 (no land opposition).
    New Georgia (Rendova landings) - 30 June 1943. Secured, 26 August 1943.
    Vella Lavella - 15 August 1943. Secured, 9 October 1943.
    Treasury Islands - 7 October 1943. Secured, 10 October 1943.
    Bougainville (Empress Augusta Bay area) - 1 November 1943. Perimeter defense until V-J Day.
    Green Island - 15 February 1944. Secured, 20 February 1944.
    Emirau Island, Saint Matthias Group - 20 March 1944. No land opposition.

"Secured" was the official term to denote the end of effective enemy opposition. The length of time between the initial attack and the date when each island was declared secured approximates the period during which malaria control activities were carried out under combat conditions.

Rear Area and Air Force Installations

The rear area installations of greatest importance were on New Caledonia, which was the headquarters of the South Pacific Area Command. This island was 1,000 miles south of Guadalcanal. During the early part of the campaign, it was an important transshipping and supply base. But, after Guadalcanal was secured, many supply activities were gradually moved to that island which became the staging area for successive attacks on Japanese-held islands to the northwest.


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There were excellent harbors at Nouméa in New Caledonia, at Havannah Harbour in Efate, and at Segond Channel in Espíritu Santo. Major naval supply and repair depots were developed at Nouméa and at Espíritu Santo, and an advance naval base was established at Tulagi in the Florida group. All these were malarious areas except New Caledonia, and even there mosquito control activities were required to prevent dengue fever which caused sharp epidemics before it was brought under control.

AREA CHARACTERISTICS AS THEY PERTAIN TO MALARIA AND ITS CONTROL

Physiography

Extent and area . - The malarious areas here discussed comprised 11 bases in the South Pacific Area. Although the total occupied area on these bases consisted of only approximately 350 square miles of territory, they were scattered over vast reaches of the Pacific Ocean (map 24). These islands, from Efate, in the New Hebrides to Emirau in the Saint Matthias Group, extend in a long chain from 17o 30' south longitude and l68o 30' east longitude to 1 o 8' south longitude and 1500 east longitude. The total distance from Efate to Emirau is approximately 1,550 nautical miles. The total area of the New Hebrides is 5,700 square miles; that of the Solomon Islands is 18,000 square miles. Espíritu Santo, the largest island in the New Hebrides, is 76 miles long and 40 miles wide. Efate, at the southernmost tip of the New Hebrides, is 26 miles long and 14 miles wide.  Bougainville, largest of the Solomon Islands, is 120 miles long and averages 40 miles in width; while Guadalcanal, the second largest of the Solomons, is 90 miles long and has an average width of approximately 30 miles.

The military occupied area of Efate and Espíritu Santo included approximately 40 square miles on each base. On Guadalcanal, approximately 110 square miles of territory on the northwest coast were occupied, although combat Operations had extended well beyond the area of occupation. On Bougainville, the area originally occupied totaled about 30 square miles but was later expanded to 50 square miles. Approximately 30 square miles were occupied on Empirau. The military occupation of other South Pacific bases involved relatively small areas, usually less than 20 square miles each.

Types of terrain and watered areas. - With the exception of Emirau, Green, and Treasury Islands, which are coral, all the malarious bases occupied during the South Pacific campaign are of volcanic origin and are mountainous. On Bougainville, Mount Balbi reaches to 10,171 feet; on Guadalcanal, Mount Popomanasiu reaches 8,005 feet; and on Espíritu Santo, Mount Tabwemasana reaches 5,940 feet. Occupied portions of the bases were usually limited to relatively narrow coastal strips, which consisted, for the most part, of coral uplifts or alluvial plains. In the occupied portions of some of the bases, the hills extended nearly to the sea; on others, such as Guadalcanal, the major portion


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MAP 25.- Espíritu Santo, New Hebrides.

of the occupied area was on an alluvial plain from 1 to 10 miles in width. There are no large rivers and only a few permanent streams on the smaller islands, but the three largest bases represented different and varying types of terrain and deserve more detailed discussion.

The occupied area on Espíritu Santo (map 25) consisted of a long, narrow coastal strip on the southeastern portion of the island, extending from Turtle


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MAP 26.- Guadalcanal, Solomon Islands.

Bay on the north to the Renee River on the south. This area is underlaid with coral, and the hills extend nearly to the sea. There are numerous large streams, some of which emerge near the coast from huge coral craters. The longer streams, arising in the mountains, are swift flowing and subject to considerable variation during times of heavy rainfall. The short streams, emerging from the coral craters, have a fairly uniform flow but are subject to considerable tidal influence, their level often fluctuating as much as 3 feet each day for a mile or more inland and sometimes to the crater source. A considerable part of the occupied area of Espíritu Santo consisted of coconut, coffee, and cacao groves.

The occupied area on Guadalcanal (map 26) extended from the Balasuna River, near the north central portion of the island, to beyond Doma Cove toward the northwestern tip and included about 45 miles of coastline. The broad alluvial plain on the north central coast of Guadalcanal becomes progressively narrower from a width of about 10 miles between the Balasuna and Metapona Rivers to less than a mile at the Lunga River, the largest of the rivers in this area. West of the Lunga, the plain narrows rapidly and beyond Kukum Point consists largely of a narrow fringing strip. The broad portion of the plain is transected at intervals of about 3 miles by major drainage courses arising in the mountains to the south. Between these rivers (Balasuna, Metapona, Nalimbiu, Tenaru, and Lunga) are numerous sluggish meandering streams.


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The beaches east of the Mataniko River, the first river west of the Lunga, are of dark volcanic sand and slope rather gently to the ocean floor. West of the Mataniko River, the beaches are of relatively coarse gravel and are more precipitous. The soil of the alluvial plain is a fine, black silt, underlaid by a yellow clay subsoil. The topsoil, when undisturbed, is capable of absorbing and holding an enormous amount of water but once packed by vehicular traffic becomes highly impervious. All the small streams between the Balasuna and the Lunga, and many of those to the westward, were periodically blocked at the mouth by sandbars built up by surf action. The coastal lagoons and swamps thus formed often remained blocked for long periods of time, permitting the development of aquatic vegetation and making ideal breeding places for Anopheles farauti.  West of the Mataniko River, streams are generally smaller than in the north central part of the island but are less likely to become blocked by sandbars at the coast because of the more precipitous beach and the oblique ocean currents striking the coast in this area. Many of the small drainage courses west of the Mataniko are dry during a part of each year.

The occupied portion of Bougainville (map 27), near Empress Augusta Bay on the southwest coast, is a recently uplifted area. The soil is volcanic sand for some miles inland, and the terrain consists of a series of sandy terraces, representing old beach lines. The eastern portion of the area contains some steep foothills. The sand terraces are transected by a few rivers and small streams, some of which were clogged by the accumulated debris of centuries with the result that each terrace contained a series of fresh-water swamps. A high water table, which quickly filled foxholes and shell and bomb craters, characterized much of the area before cleaning of drainage courses, but subsoil drainage was generally good. As on Guadalcanal, streams were often blocked at the mouth by sandbars to form coastal lagoons.

Prevailing vegetation covers. - The occupied malarious bases of the South Pacific lie within the true tropic belt, and the vegetation of these islands is accordingly influenced greatly by the climate of the tropics. For purposes of discussion, it is convenient to distinguish between the low coral formations, such as Emirau, Green, and Treasury Islands, and the larger volcanic islands that constituted the remaining bases.

Because of the very porous condition of the soil, the coral islands are without tropical rain forests and have relatively little dense growth that approximates true jungle. The vegetation consists primarily of coconut palms, low-growing brush, grass, and weeds. More luxuriant, junglelike growth occurs in the marshy areas of the islands. Vegetative cover was not an important factor in malaria control operations on these islands.

The larger volcanic islands of the South Pacific are typically covered with heavy rain forests except along the coast where narrow strand formations occur. The coastal areas, and sometimes the inland areas as well, are often occupied by extensive plantings of coconut palm, coffee, and cacao. There


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MAP 27.- Bougainville Island.

are occasional rubber plantations and other cultivated tropical plants. Since plantation areas are usually level and open, they were widely used for bivouac areas and supply dumps. As such, they became an important part of the malaria control problem.

The coastal strand formation consists of two general types. Around the tidal mudflats at the mouths of the numerous permanent streams, mangrove swamps are common. These mangrove swamps were of little importance ex-


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cept in the innermost portions where tidal action was minimal and relatively fresh water permitted the growth of aquatic vegetation. On the beaches, between streams, the strand formation consists of coconut palms intermixed with scattered large forest trees growing to a height of 60 feet or more. Occasionally, there are huge banyan trees. In most places, a dense undergrowth extends to within a few feet of the high tide line, and, except on the more barren shores, the undergrowth within the strand formation is almost impenetrable. The secondary plants making up the strand formation contain such forms as Hibiscus, Pandanus, and a herbaceous ground cover of tangled vines, grasses, sedges, and other low plants. The entire formation is narrow, often no more than a few yards in width.

Wherever they occurred and had been maintained, plantations were relatively open at ground level. Before military occupation on most bases, and throughout the occupation on some, cattle were widely grazed in cocoanut groves. Grazing together with periodic removal of secondary undergrowth maintained such groves as open, parklike areas offering easy passage for traffic of all kinds. Coconut groves that were not grazed or otherwise maintained quickly developed into a thick tangle of young cocoanut palms, brush, and tall grass. Coffee and cacao plantations, being heavily shaded by towering jungle trees, had somewhat sparse ground cover. The orderly arrangement of the plantings and their excellent camouflage qualities made them ideal for supply dumps. When used for that purpose, however, roads were but rarely constructed until after long use. This resulted in mile after mile of water-filled ruts caused by the movement of heavy vehicles between the rows of trees. Plantations in general, and coconut plantations in particular, became one of the big problems from a malaria control standpoint.

The true rain forest formation consists of a towering canopy of trees reaching to 150 feet in height, with successively lower layers of trees which supply a very dense shade at ground level. Various climbing plants, some of which extend to the uppermost canopy, form an undergrowth that is difficult to penetrate except along established trails. Off the trails in the jungle, where it is necessary to hack a way through the undergrowth with machetes, a half-mile per hour is considered a rapid march speed. Even along trails, rapid movement is impossible because of the slippery footing, obstructing roots, and the long, whiplike extensions of the rattan palm that hang across the trails and grasp at clothing or flesh with sharp, stout, recurved spines. Because of high humidity, lack of aeration, and difficulty of clearing these areas, the true rain forest was little used for bivouac purposes and only to a limited extent was it necessary to extend malaria control activities into this type of growth.

The plant formations of Guadalcanal,7 and to a limited extent those of Tulagi, differ considerably from those encountered on others of the major

7 Pendelton, R. C.: The Rain Shadow on the Plant Formations of Guadalcanal. Ecological Monographs 19: 75-93, 1949.


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South Pacific islands. Guadalcanal lies athwart the prevailing trade winds in the area, and the high mountains in the central part of the island, forcing the air upward, cause heavy rainfall on the south side of the island and diminished rainfall on the northwest coast. Within this area of rain shadow effect, which extends to Tulagi, there is a greater seasonal variation in rainfall than is characteristic of parts of the island not influenced by high elevations in the path of the trade winds, and a total rainfall somewhat less than is required to support tropical rain forests. This results in the absence, from the northwest coast of Guadalcanal, of true rain forest formations and accounts for the extensive grasslands of the coastal plain and lower hills. Because these extended grasslands and associated vegetative features had a profound influence on the malaria control problem on Guadalcanal, they are discussed in some detail.

On the eastern part of Guadalcanal, where seasonal variation and total rainfall is not influenced by high elevations in the path of prevailing winds, there is dense rain forest. From the Berande River, some 4 miles east of the limits of the occupied area, to the northwestern tip of the island, the vegetation of the north coast is influenced by the rain shadow caused by mountains. This portion of the island is characterized by extensive grasslands, while the high central part of the island and the south side are covered by rain forests. 'The northwest coastal area is transected by numerous rivers and smaller streams, and along most of these there is a strip of forest connecting the forests of the hills with the narrow coastal-strand formation.

Although these forest strips along stream courses are narrow, being in some places only a few hundred feet in width, they consist of much the same type of vegetation as is encountered in typical rain forests. These jungle strips rise abruptly from the grasslands to a height of 100 feet or more, often with scattered taller trees reaching many feet higher. The height and uniformity of the vegetation increases with the width of the jungle zone bordering the stream, and forest belts along the larger permanent streams present a relatively uniform canopy. The vegetation bordering temporary streams usually consists of a narrow belt of trees of various heights, so that from a distance the canopy presents a ragged appearance. Because these forest belts admit a considerable amount of sunlight, the undergrowth is frequently more dense than that of true rain forest, particularly at the forest edge. From the standpoint of mosquito control operations, these jungle strips were comparable to true rain forest. On Guadalcanal, they were widely used for bivouac and supply areas when cocoanut palm groves, were not available.

The extensive grasslands are the dominant vegetative feature of the northwest coast of Guadalcanal. Between the Berande and Lunga Rivers, they occupy the major portion of the flat coastal plain and extend inland for several miles. well into the foothills. West of the Lunga, where the coastal plain becomes progressively narrower toward Cape Esperance, the grasslands are largely on the rugged foothills. The dominant grass in these areas grows to


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a height of 4 to 6 feet, forming a tangled mass of vegetation that is often more difficult to penetrate on foot than is the jungle. On the flat alluvial plain between the Balasuna and Lunga Rivers, these open grasslands offered an inviting area to drivers of vehicles, either on legitimate business or aimless exploring. Soon the entire area was crisscrossed with innumerable trails, most of which became badly rutted and held water either periodically or constantly. Once a trail became impassable because of rutting, a new trail parallel to the old one would be started, adding to the miles of ruts. The elimination of these road ruts, and the closure of the grasslands to indiscriminate driving, became a major malaria control problem on Guadalcanal.

Climatic Features

In general, it may be said that the climatic features of the South Pacific islands favor malaria. The absence of the vector of malaria, and hence the absence of the disease from many of the smaller islands in the malarious zone, appears to be correlated with physiographic rather than climatic features. Although rainfall is abundant throughout the area and the temperatures are high and fairly uniform, many of the smaller coral islands have no permanent fresh water suitable for anopheline breeding.

Rainfall.- On all bases, the total yearly rainfall was high, usually exceeding 100 inches. This factor, coupled with a constantly high humidity, served to keep the soil well saturated during the greater part of the year. The terms "dry season" and "wet season" are relative; during most months of the year, there was sufficient rainfall to maintain numerous small surface pools of water. During the period from June to August, the intertropical front is north of the Equator and the prevailing winds are from the southeast. This is the so-called dry season. From December to February, when the intertropical front is south of the Equator, the prevailing winds are from the northeast. The periods from March to May and from September to November are characterized by unsettled weather when the. doldrums and their intertropical fronts are moving across the Equator. Marked seasonal variation in rainfall, such as occurs on the northwest coast of Guadalcanal, may have been due to local topographic features. During the so-called wet season, heavy rains may be expected daily for as much as a week at a time. As much as 36 inches of rainfall in 1 month has been recorded for Bougainville (Kieta) ; the total rainfall for March 1944 on Espíritu Santo was 28 inches, of which 10.5 inches fell during one 24-hour period on 27 March.

The influence of rainfall on the problems of malaria control is difficult to evaluate, but it was undoubtedly the most important single factor in causing seasonal variations in the problems. Periods of heavy rainfall, causing flushing of drainage courses and opening of some lagoons, resulted in the temporary elimination of anopheline breeding from most streams. The great increase in surface water that resulted from heavy rains served to disperse current larval


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populations and gave the impression that there was some cessation of breeding. On most bases, peak anopheline populations usually occurred soon after the cessation of heavy rains. A number of factors apparently contributed to this situation. The stabilization of abundant water surfaces combined with increased sunlight and its resultant effect on the development of plant life to make conditions ideal for larval development. Larvicidal crews were frequently unable to obtain complete coverage for several days or weeks following heavy rains.

Temperature . - There is little variation in temperature at sea level in the Solomon Islands, and the daily temperature range is remarkably uniform throughout the year. The maximum daily temperature rarely exceeds 94 0 F., and the minimum is seldom below 67 0 F. The usual daily temperature variation was about 20 0 F. from a high of about 90 0 to a low of about 70 0 F. These temperatures, together with a high relative humidity of approximately 80 percent, provided almost optimal conditions for mosquito development. At no time were temperatures in the Solomon Islands bases so low as to be considered unfavorable to anopheline breeding.

Temperatures in the New Hebrides exhibited a greater range of daily variation, as well as less uniform daily change throughout the year. Temperatures as low as 53 0 F. were recorded at Segond Channel on Espíritu Santo, and as low as 58 0 F. on Efate. Maximum temperatures of 98 0 and 95 0 F., respectively, were recorded for these two bases. Because the periods of both low and high temperatures were relatively brief, it is doubtful if these extremes had any appreciable effect on mosquito development.

Local Population

New Hebrides . - The population of the New Hebrides in 1939 was given as 218 British, 687 French, 2,282 Asiatics (Tonkinese, Chinese, and Japanese), and about 40,000 native Melanesians. Of the Melanesians, about 4,000 lived on Espíritu Santo and 1,700 on Efate, mostly in small, independent villages scattered through the islands.

During the first part of the occupation of Efate and Espíritu Santo, the troops were bivouacked near labor camps of natives who were heavily seeded with malaria, and in areas where anophelines were numerous. Later on, troop concentrations were kept away from local communities as much as possible, but this could not be done in outlying areas.

In the New Hebrides, yaws, hookworm infestation, malaria, dysentery, and tuberculosis are endemic. Wucheria bancrofti is also present. The results of surveys by the malaria control organization follow.

Solomon Islands and Saint Matthias Group . - The natives of the main Solomon Islands and the Saint Matthias Group are Melanesians. In 1939, the population of the Solomons, including Bougainville, was given as 500 Caucasians, 140,000 Melanesians, and 200 Chinese. At the time of Allied


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occupation, most of the Caucasians had fled. The population of Guadalcanal was about 20,000 and that of Bougainville about 45,000. The natives lived rather primitively in small villages, family groups, or families.

When the fighting began in the Solomons, the local inhabitants left the combat areas. After the islands had been secured, they were usually prevented from reentering the troop area. Native labor camps, however, were at first often located in the troop area. Later, some were moved away. Local traders also visited the troop areas during the daytime to trade, but were not permitted to sleep there.

Solomon islanders are heavily infected with tuberculosis, yaws, and hookworms. In surveys of 2,500 Guadalcanal residents carried out by military malaria control personnel, 22 percent were found to have W. bancrofti microfilariae in their blood. Malaria is hyperendemic among the natives.

Incidence of malaria. - Data on the incidence of malaria in the New Hebrides, Solomon Islands, and Saint Matthias Group have been given by Levine and Harper. 8 In addition, the report of Sayers 9 on malaria in the New Georgia Group, Solomon Islands, became available during the war. Sayers, who had conducted a hospital at Munda and later at Vella Lavella, Solomon Islands, from 1927 to 1934, had treated 741 parasite-positive natives from a population of about 6,000. In these clinical cases, Plasmodium falciparum was present in 44 percent, Plasmodium vivax in 32 percent, Plasmodium malariae in 18 percent, and undetermined species in 6 percent. The splenomegaly rate among 365 children was 73 percent. Clinical malaria was not common in New Georgia natives over 30 years of age.

The malaria rates reported by the military malaria control personnel were based on single-smear surveys made on thick smears stained with Giemsa stain. They are not comparable with Sayers figures, since his were based on clinical cases.

The prevalence of malaria observed in these surveys is given in table 59. The surveys on natives of Malaita and San Cristobal, Solomon Islands, and one of those on Guadalcanal were made on adult male laborers who were living in labor camps on Guadalcanal at the time of examination. The parasite rate was relatively low in these three surveys, ranging from 7 to 11 percent. Since the parasite rate among the Guadalcanal villagers was 52 percent and the rate among the Guadalcanal laborers was 10 percent, it is clear that the prevalence of Plasmodium in healthy, adult laborers cannot be taken as indicative of the rate among the people as a whole.

    Plasmodium species distribution . - The species of Plasmodium encountered in the surveys are given in table 60. P. vivax was the most common on all islands except Emirau, being found in 41 to 88 percent of the positive

8 Levine, N. D., and Harper, P. A.: Malaria and Other Insect-Borne Diseases in the South Pacific Campaign, 1942-1945; IV. Parasitological Observations on Malaria in Natives and Troops, and on Filiariasis in Natives. Am. J. Trop. Med. 27 (suppl.) : 119-128, May 1947.
9 Sayers, E. G.: Malaria in the South Pacific with Special Reference to the Solomon Islands. New Zealand Government Printing Office, 1943.


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smears from these islands. The most common species on Emirau was P. falciparum, which was present in 45 percent of the smears. On the other islands, this species was found in 6 to 37 percent of the positive smears. P. malariae was not found on Efate, Treasury, Malaita, or San Cristobal Islands. However, surveys on the last two islands were made on adult laborers. P. malariae comprised 25 percent of the positive smears on Emirau and 20 percent of those on Savo. Its prevalence on the other islands ranged from 0.5 to 12 percent.

TABLE 59.- Prevalence of malaria parasitemia on South Pacific islands

Relation of age to prevalence of malaria and species of Plasmodium . - In surveys made on Guadalcanal, 91 percent of 44 children from birth to 5 years of age, 72 percent of 51 children from 6 to 15 years of age, and 38 percent of 96 persons over 15 years of age carried plasmodia in their blood. Similar decreases in prevalence with age were found on Savo, Green, and the Russell Islands. On Guadalcanal, the most common species in all age groups was P. vivax. In the youngest age group, P. falciparum was the least common species, but its prevalence was higher in the two older groups, while that of P. malariae decreased with age. The prevalence of P. falciparum also increased with age on the other islands but that of P. malariae was variable.

Splenomegaly rates . - Splenomegaly was observed in 61 percent of 110 residents on Ef ate, 57 percent of 101 on Espíritu Santo, 73 percent of 258 on Guadalcanal, 70 percent of 37 natives on Florida, 57 percent of 219 laborers


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TABLE 60.- Plasmodium species in South Pacific surveys

from Malaita, 66 percent of 193 residents on the Russells, 75 percent of 500 natives on Bougainville, 57 percent of 219 laborers from San Cristobal Island, 34 percent of 37 villagers on Treasury, 65 percent of 542 natives from Green, and 85 percent of 263 on Emirau.

Mosquito Vectors of Malaria

Six species of Anopheles are known to occur in the islands of the South Pacific Area. These species and their recorded distribution are as follows:

                                                                                                Area
Anopheles farauti Laveran 1902............................................All malarious bases.
Anopheles koliensis Owen 1945............................................Guadalcanal, north coast.
Anopheles lungae Belkin and Schlosser 1944.........................Guadalcanal, north and northeast coast; Empress Augusta         Bay, Bougainville; Munda, New Georgia.
Anopheles nataliae Belkin 1945.............................................Guadalcanal, north coast.
Anopheles punctulatus Dönitz 1901.......................................Guadalcanal, north and south west coasts; Empress Augusta Bay, Bougainville.
Anopheles solomonis Belkin, Knight, and Rozeboom 1945.....Guadalcanal, northwest coast; Munda, New Georgia.

Characteristics of malaria vectors

In the South Pacific Area, the principal vector of human malaria, and probably the only one of military importance, was A. farauti Laveran (fig.


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FIGURE 53.- Principal vectors of malaria in the South Pacific Area. A. Anopheles ferauti Laveran. B. Anopheles koliensis Owen.

53A). Anopheles koliensis Owen (fig. 53B) was known to be strongly anthropophilic and thus potentially an important vector but of limited geographic distribution. In the limited area on Guadalcanal, in which it is known to occur, it may have been of some consequence during the period of combat and early occupation. Available information indicates that other species of Anopheles were not involved in the transmission of malaria to troops.


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Breeding habits. - Anopheles farauti larvae usually occurred in greatest numbers and highest concentrations in sunny, slightly brackish lagoons in association with emergent aquatic vegetation and surface debris. The species also utilized almost every conceivable type of aquatic habitat with the exception of artificial containers, tree holes, open moving water, and highly saline water. On occasions, A. farauti larvae were even found in artificial catchments when these were of sufficient size to approximate ground pools. The ability of the species to utilize these many types of habitats greatly influenced its importance as a malaria vector. It occurred abundantly in permanent or temporary surface water catchments of all kinds, in tidal and fresh-water swamps and lagoons, and to a lesser extent in streams, seepage areas, and open wells. Although it preferred sunlit water, it also occurred in rather heavily shaded areas. The larval developmental period was short, especially during the so-called dry season when prolonged periods of sunlight considerably increased the water temperature of typical breeding habitats.

Observations on Guadalcanal showed that under favorable circumstances A. farauti could complete development from egg to pupa in 5 days, and from egg to adult in 8 days. The normal developmental cycle from egg to adult was usually considered to be between 7 and 10 days, and larvicidal schedules were arranged accordingly. The ability of A. farauti to initiate an epidemic of malaria is clearly illustrated by the experiences of combat troops during the early phases of the Guadalcanal Campaign.

Insofar as they are known, the larval habitats of A. koliensis are similar to those of A. farauti, although information is not available to indicate whether or not A. koliensis adapts itself to the wide range of habitats that are utilized by A. farauti. During periods of prolonged rainfall, A. punctulatus larvae are found in typical A. farauti habitats, but during the dry season this species disappears from the coastal section of Guadalcanal. Anopheles lungae occurs in coastal swamps and seepage areas and shows a decided preference for shaded habitats. Both A. solomonis and A. nataliae occur in the low foothill section along the northwest coast of Guadalcanal, the former having been collected from potholes in a coral streambed and from seepage areas. Both species were usually found in clear water, densely shaded.

Habits of adult Anopheles. - All the species of Anopheles encountered in the South Pacific Area were nocturnal in their biting habits, although under favorable conditions of low light intensity daytime biting by A. farauti was not uncommon. This species was observed to bite as early as 1500 hours in jungle area on a cloudy day and as late as 0730 hours in thatched huts on a relatively bright day. Normally, the biting activities of A. farauti were limited to the period from dusk to shortly after dawn. Practically all Anopheles caught in routine night-biting catches on Guadalcanal were A. farauti, except for the relatively limited area in which A. koliensis was known to occur.

Man is generally considered to be the normal host of A. farauti perhaps in part because there are usually few other large mammals available in the


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South Pacific islands. However, host preference tests conducted on Efate showed that the species fed readily on cattle, horses, goats, pigs, dogs, and chickens. Available evidence also indicates the probable existence of host-adapted strains of A. farauti on Guadalcanal. In 1944, numerous attempts were made to attract adult A. farauti to humans at night in the vicinity of an abandoned plantation near the mouth of the Balasuna River. Although weather conditions were favorable for mosquito activity, and high larval and pupal populations were known to exist in nearby lagoons, no adults were seen. Similar observations were made in other areas remote from existing human habitations. It was also repeatedly observed that adults reared from larvae collected outside the zone of normal human activity fed rarely or not at all on humans under laboratory conditions. On the other hand, specimens in captivity reared from the eggs of gravid females captured in native villages usually fed readily on humans. The successful colonization of A. farauti for laboratory study was usually accomplished by starting the colony with such material. Inadequate facilities and lack of time prevented detailed study of this interesting and probably important phenomenon.

As previously indicated, A. koliensis was strongly anthropophilic and frequently taken in night catches with humans as bait, and in the tents and thatched huts of native laborers. Anopheles punctulatus and A. lungae were but rarely attracted to humans, even when existing populations were high.

The daytime resting places for both A. farauti and A. koliensis, except for recently engorged females, apparently consisted of any cool, moist, shaded place. Because adult population sampling is generally thought to be the most accurate measure of an existing mosquito population, many efforts were made to seek out the daytime resting places of A. farauti in the South Pacific. Although almost every conceivable type of habitat was explored, at no time were adults encountered with sufficient consistency or in sufficient numbers for this method to be used as a basis for measuring the effectiveness of a control program. On the day following a nocturnal blood meal, A. farauti and A. koliensis females frequently remained in the dark parts of native huts or tightly closed tents but would leave by dusk or shortly thereafter. There was little evidence to indicate that blooded females lingered after obtaining a meal in open tents such as were usually used by troops, in thatched shelters without walls, or in the more open type of native huts.

Observations conducted during 1944 on Guadalcanal, involving daily counts of the Anopheles resting in pyramidal tents used to house Melanesian laborers, showed that the population remained fairly constant but consisted almost entirely of freshly blooded females.

    Anopheles punctulatus and A. lungae were observed to rest during the daytime on the moist, lichen-covered surface of the buttressed bases of huge forest trees in deep jungle shade. Only rarely were specimens of A. farauti observed in such places.


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Results of Combat and Occupation on Malaria Potentialities of the Area

The full significance of the changes which led to increased mosquito breeding under conditions of combat and occupation in the South Pacific Area are appreciated only when viewed in contrast to the conditions prevailing in jungle or tropical areas occupied only by local populations. Before invasion or occupation, extensive breeding of A. farauti was limited largely to coastal lagoons and native clearings along inland streams, if one may correctly judge by the situation pertaining in those areas not disturbed by occupation forces. Although mosquitoes were almost invariably present in isolated native villages, the numbers were small.

With the advent of combat and occupation, and its associated myriad activities of supply and movement, there were soon created innumerable water catchments such as shell and bomb craters, abandoned gun positions and bomb shelters, foxholes, and ruts made by vehicular traffic. Airfield construction and roadbuilding, often hastily done, created further impoundment of water. Once created, these water catchments could never be quickly eliminated because of the limited amount of personnel and equipment that could be assigned to malaria control activities. Anopheles farauti soon utilized these many water surfaces for larval development, with the result that there was a rapid and enormous increase in the anopheline population of the area. Because personal protection from the bites of mosquitoes during combat and early occupation was difficult to attain, a high percentage of the female Anopheles were able to obtain blood meals, further enhancing the mosquito breeding and malaria transmitting potential.

MALARIA EXPERIENCE

Admission rates for malaria in Army personnel in the South Pacific theater are given in tables 61, 62, 63, and 64. Since these rates include both malarious and nonmalarious bases, they do not give a true picture of the situation in the command. Since Army, Navy, Marine, and Allied troops lived in close proximity and since different islands differed markedly, a much better picture of the situation is given if the rates of all troops are considered on each island. Rates in these tables refer to clinical malaria cases and do not indicate the actual malaria infection rate. Many troops on suppressive Atabrine therapy did not develop clinical malaria until after they had stopped taking the drug. An indication of the true infection rate was obtained in units which were taken off suppressive Atabrine therapy after having become more or less heavily seeded with malaria.

Efate . - Efate was the first malarious island to be occupied in the South Pacific. Troops landed, in March 1942, to build an airfield. They were bivouacked near a native labor camp in an area where anophelines were numerous. They lacked sufficient bed nets and were required to work at night.


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TABLE 61.- Admission rates for malaria in combined Army, Navy, Marine, and Allied troops in selected areas of the South Pacific, by month and year, April-December 1942

Furthermore, they did not realize how serious malaria could be. The malaria rate reached 2,678 per 1,000 per annum in April (table 61). Quinine was the only antimalarial drug available, and in May about one-half the troops were ordered to take 0.33 gm. quinine daily; this amount was later increased to 0.66 gm. daily. These amounts failed to suppress the disease satisfactorily, and in July, 0.4 gm. Atabrine weekly was begun. The first malaria control personnel, one Navy officer and three enlisted men, arrived on 28 July 1942. Malaria rates decreased to 982 per 1,000 per annum in May and continued to decline until they reached a low of 144 per 1,000 per annum in September. This decline was due to the initiation of insect control measures, to suppressive therapy, and to the onset of the dry season. Atabrine was given to the villagers, and their huts near the troop areas were sprayed daily with a pyrethrum spray. The largest native labor camp was not moved to a safe distance from troops until nearly a year after the original epidemic. Antimosquito work was well organized by early 1943, but heavy equipment for semipermanent mosquito control work did not become available until 16 months after the first landing.

Suppressive Atabrine therapy was discontinued in September 1942 because of the low malaria rate. The rate promptly increased, reaching 520 per 1,000 per annum in November. Suppressive Atabrine therapy was resumed in November except for lightly seeded personnel living in screened quarters, and the malaria rate again decreased. In 1943, many of the heavily seeded troops left Efate, and the remaining troops were withdrawn from poorly controlled areas. By July 1943, the malaria rate was 128 per 1,000 per annum, of which only 66 were original admissions (table 62). At this time suppressive Atabrine therapy was discontinued on the island. The subsequent rates remained low, with a high percentage of relapses.


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TABLE 62.- Admission rates for malaria in combined Army, Navy, Marine, and Allied troops in selected areas of the South Pacific, by month and year, January-December 1943


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TABLE 63.- Admission rates for malaria in combined Army, Navy, Marine, and Allied troops in selected areas of the South Pacific, by month and year, January-December 1944


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TABLE 64.- Admission rates for malaria in combined Army, Navy, Marine, and Allied troops in selected areas of the South Pacific, by month and year, January-June 1945

Espíritu Santo. - This island was occupied without opposition in May 1942. The dry season had begun, and there was very little mosquito breeding near the campsites. Even though drug suppression was not practiced, no cases of malaria were reported until September. In September, October, and November, fresh troops were camped near heavily seeded natives in anopheline breeding areas. The more exposed personnel were placed on suppressive Atabrine therapy, and the malaria rate did not rise beyond 255 per 1,000 per annum.10 It reached this level in January 1943, and thereafter declined slowly (table 62). After the original admission rate had reached 109 per 1,000 per annum in May 1943, suppressive Atabrine therapy was discontinued. The rate continued to drop, the original admission rate being 16 per 1,000 per annum in November 1943 and declining still further later on.

A base malaria control group consisting of two Navy officers and eight Navy enlisted men was set up in September 1942. Troop areas were kept as far from local settlements as possible. The inhabitants were given suppressive Atabrine therapy, and their huts were sprayed regularly with pyrethrum beginning early in 1943. Residual spraying of the huts with DDT was begun in mid-1944. An extensive larviciding and semipermanent control program was in operation by mid-1943. It was so effective that after this time it was unusual to find adult anophelines in the main troop areas. Outlying areas, however, continued to be highly malarious, and troops on outpost duty became heavily infected.

Guadalcanal . - The first landing on Guadalcanal was made by Marine units in August 1942. The first Army units arrived in October. At first anti-malaria supplies were either unavailable or inadequate, and no significant amount

10 Malaria rates on Espíritu Santo are not comparable with those on the other islands. Only cases contracted on Espírito Santo are included, while on the other islands all cases wherever contracted (except cases among hospital patients admitted on an in-transit basis) are included.


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of mosquito control was done. The fact that there were few cases of malaria in August and September led to the feeling that the disease would be unimportant. No malaria control measures were undertaken during the early months, partly because of the desperate military situation and partly because responsible officers did not understand how serious a hazard malaria could be. The prevailing attitude was expressed by one high ranking officer who said: "We are here to kill Japs and to hell with mosquitoes."

However, the terrain and the results of combat combined to produce ideal conditions for the breeding of enormous numbers of mosquitoes. The combination of abundant anopheline breeding, a highly malarious source of infection (the native Melanesians and the Japanese troops), and almost complete absence of antimalaria precautions caused the malaria rate to rise precipitously to 1,664 per 1,000 per annum in October 1942 and to 1,781 in November (table 61). Malaria remained epidemic for at least 9 months. Of the estimated 100,000 cases of malaria contracted in the South Pacific, more than three-fifths were probably contracted on Guadalcanal, and most of these during the period October 1942 to August 1943. In July 1943, the malaria rate was 608 per 1,000 per annum, of which 342 per 1,000 per annum were original admissions (table 62). The rate dropped to 263 per 1,000 per annum (of which 142 were original admissions) in August 1943 and continued to decline steadily thereafter. In February 1944, when the original malaria admission rate was 74 per 1,000 per annum, suppressive Atabrine therapy was discontinued in lightly seeded units. The rate continued to decrease. By October 1944, about 26 percent of the troops bad been taken off Atabrine, the total malaria rate was 51, and the original admission rate was 22 per 1,000 per annum (table 63). By June 1945 over 75 percent of the troops had been released from suppressive Atabrine, the total malaria rate was 9, and the original admission rate, 6 per 1,000 per annum (table 64).

A base malaria control group consisting of two Navy officers and eight Navy enlisted men was established in November 1942. This organization was later expanded greatly, and Army personnel eventually predominated. By far the largest amount of antimalaria work on any island was done on Guadalcanal. By the latter part of 1943, control work was well advanced. After that time, adult anophelines were difficult to find in the occupied area except during sporadic infestations.

The most important measure responsible for the great decline in the malaria rate was the extensive mosquito control work, both larvicidal and drainage, which was carried out. Atabrine suppressive therapy lowered the rates in heavily seeded troops. Administration of suppressive Atabrine and mass therapy to natives, spraying of their huts, and removal of native labor camps from troop areas (not accomplished completely until August 1944) were also helpful. Other factors were the improvement in living conditions for the troops, particularly the provision of screened quarters, and extensive education in personal malaria preventive measures.


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During the early period, troops which had staged in uncontrolled areas on Guadalcanal for only a few days and then moved on to other islands often had severe malaria outbreaks traceable to their exposure on Guadalcanal. To prevent this, a troop bivouac area of about 90 square miles was established in November 1943. Mosquito control was carried out here continually. No organization was allowed to bivouac outside this area without special permission.

Tulagi-Florida Islands. - The initial landing in the Florida group of islands as made in August 1942. Combat did not last long, but small groups of troops were widely scattered and had inadequate antimalaria supplies. A Navy malaria control group began its activities late in 1942. Before this time, no malaria rates for all troops were available, although in one organization of 237 men the malaria rate was 2,004 per 1,000 per annum in December 1942, when the men were supposedly taking 0.4 gm. Atabrine a week.

The highest total rate for this small group of bases was 593 per 1,000 per annum in May 1943 (table 62). Most of the cases were in a few units in poorly controlled areas. Atabrine suppression therapy was discontinued in about one-half the troops in August 1943; it was discontinued in all troops in September 1944. At this time, the total malaria rate was 58, and the original admission rate, 16 per 1,000 per annum (table 63). Effective mosquito control work played the major part in reducing the malaria rate on these small bases. It was made difficult and complex by their scattered situation.

Russell Islands . - Unopposed landings were made on the Russell Islands in late February 1943, and a base malaria control unit arrived on March 3. There were neither natives nor Japanese on Banika or Pavuvu, the two main islands occupied. Mosquito breeding sites were numerous; hundreds of ponds about 30 feet in diameter were present in the coconut plantations.

The 43d Division, which made the initial landings, had been seeded with malaria on Guadalcanal, as had many of the troops which arrived later. Antimalaria details were established in all units of the 43d Division and in the Navy and Marine units within a month of occupation. A small staff of malaria control personnel was able to effect a very considerable degree of control under conditions which were favorable to the development of epidemic malaria. The malaria rate for March was 281 per 1,000 per annum, most cases being caused by P. falciparum. Suppressive Atabrine therapy was given at the rate of 0.4 gm. per week, a dosage later found to be inadequate; supervision was unsatisfactory. As a consequence, malaria rates of 200 to 400 per 1,000 per annum continued through September. However, unseeded units which came to these islands did not develop these high rates.

New Georgia Group . - The 43d Division attacked Rendova Island in the New Georgia Group on 1 July 1943 and assaulted Munda in mid-July; the 37th and 25th Divisions joined it later. During the first 2 months, heavy combat caused the formation of many shellholes, bomb craters, foxholes, nits, and other sources of mosquito breeding. The seedbed consisted of Japanese and already infected Allied troops. The Allied troops were presumably taking


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0.4 gm. suppressive Atabrine weekly, but its administration was poorly supervised. Anopheline breeding rapidly became a serious problem both on Rendova and New Georgia.

A malaria control team consisting of an Army malariologist, a Navy parasitologist, and several corpsmen landed on Rendova on 11 July and moved to Munda in August. This group early initiated a control program on Rendova which kept mosquito breeding at low levels and then vigorously attacked anopheline breeding areas in the main occupied areas of New Georgia. This was the first attempt to control malaria under combat conditions in the South Pacific Area and demonstrated that a small group of trained personnel with simple equipment could accomplish much valuable work. It was a new concept in malaria control and was the basis for the subsequent assignment of survey and control personnel to all large combat units.

The malaria rate reached a peak of 629 per 1,000 per annum in September 1943; much of this was due to relapses in the heavily seeded 25th Division which had a rate above 1,000 per 1,000 per annum at this time. By December, most of the heavily seeded units had left the base, and the rate was 258 per 1,000 per annum. By May 1944, it had dropped to 51 per 1,000 per annum.

Vella Lavella . - Vella Lavella was invaded on 15 August 1943 by the 3d New Zealand Division and a small American force. It was secured on 9 October. A malaria control unit consisting of 4 officers and 33 enlisted men arrived with the division, and a Navy control group was also present. Most of the malaria cases occurred in a Marine defense battalion which had been heavily seeded on Efate in 1942. The rate in this battalion was 964 per 1,000 per annum in April 1944; at the same time, the island rate was 329 per 1,000 per annum (table 63). The method of administration of suppressive Atabrine in this battalion was improved; in May its malaria rate had fallen to 114, while the island rate was 54 per 1,000 per annum. The continuing low rates in the previously unseeded New Zealand division are a tribute to its malaria discipline and effective larviciding program.

Bougainville . - The landing was made at Empress Augusta Bay, an almost uninhabited area, in November 1943. Malaria control groups accompanied the 3d Marine, Americal, and 37th Divisions. A base malaria control group was established in January 1944. Because there were extensive swamps near the beach, the troop area was established at some distance from the beach, where the underlying sandy soil proved easy to drain. Control work was started early, and the malaria rate never became high. A peak rate of 119 per 1,000 per annum was recorded in January 1944 (table 63). Even though many of the troops were already seeded, 0.6 gm. weekly of suppressive Atabrine helped keep the rate low. Aerosol bombs were available and were widely used.

Minor outbreaks of malaria occurred in troops on perimeter defense and in those making sorties into enemy territory. Most of these cases were due to P. falciparum. while most of those in the controlled area were relapses due to P. vivax.


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Emirau Island. -An unopposed landing was made on this small island in March 1944. A malaria control group accompanied the troops and began a very effective mosquito control program immediately. Even heavy equipment drainage of all swamps was completed in 3 months. The 220 natives who lived in Emirau were moved to another island.

The malaria experience of some of the Army units is of particular interest, since their personnel did not change so much as did those on the various islands.

Americal Division . - This division moved to Gaudalcanal by echelons in October, November, and December 1942. The troops lived and fought in highly epidemic areas. There was very little malaria discipline, no repellents or Aerosol bombs, and, although 0.4 gm. Atabrine weekly was prescribed, it is doubtful if it was taken very carefully. The monthly malaria rate ran as high as 1,358 per 1,000 per annum, while the division was on Guadalcanal.

In March 1943, the division was moved to Fiji, a nonmalarious island, for rehabilitation. The entire division was treated with Atabrine and Plasmochin between April and June. Thereafter, no antimalarial drugs were administered except to persons with clinical malaria. The malaria rate rose promptly to a high of 3,760 per 1,000 per annum in August; it was still 2,880 per 1,000 per annum in October. The division was alerted for combat in November, and suppressive Atabrine therapy was given at the rate of 0.4 gm. per week. This was increased in December to 0.6 gm. per week. By January, the malaria rate had fallen to 43 per 1,000 per annum. After 5 months of combat on Bougainville, the total rate for May 1944 was only 112 per 1,000 per annum. More details on malaria in this division are given by Tumulty and coworkers.11 The malaria experience of this division is shown in chart 20.

    Plasmodium falciparum caused more than one-half of all malaria cases reported on Guadalcanal during January, February, and March 1943, and P. vivax caused about 25 percent of the cases. Plasmodium falciparum continued to predominate for a few weeks after the division arrived on Fiji, but P. vivax rapidly came to the fore and caused practically all the subsequent cases.

Suppressive Atabrine therapy was discontinued on Fiji in the hope of demalarializing the division. The theory was that if the troops were allowed to have their malaria, they would get it out of their systems and become free of it. The experience with this and other units showed that this would not take place within a reasonable length of time but that repeated relapses would occur.

147th Infantry . - This regiment landed on Guadalcanal in November 1942 and February 1943, and took part in combat. The regiment was on 0.4 gm. weekly suppressive Atabrine, but its administration was not closely supervised. While most of the diagnoses were not confirmed by blood smear examination,

11 Tumulty, P. A., Nichols, E., Singewald, M. L., and Lidz, F.: An Investigation of the Effects of Recurrent Malaria; an Organic and psychological Analysis of 50 Soldiers. Medicine 25: 17-25, February 1946.


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CHART 21.-   Incidence of malaria in the 147th Infantry, December 1942 to October 1944, inclusive
 

the regiment's sick reports showed malaria in 48 percent of the men, and the malaria rate reached a peak of 1,558 per 1,000 per annum in April 1943.

In May 1943, the regiment was sent to British Samoa, a nonmalarious island, and demalarialization was begun. Downs 12 described the malaria history of this regiment in detail. The regiment was divided into four groups. One received Atabrine mass therapy at once; the second received Atabrine mass therapy after a 10-day period without medication; the third received mass therapy with Atabrine and Plasmochin; and the fourth received no mass therapy. Suppressive treatment was then discontinued, although clinical cases were treated as they occurred.

There was no relationship between the treatments and the incidence of malaria in the four groups. Because the termination of mass therapy was staggered, the peak malaria rate of the regiment did not exceed 4,090 per 1,000 per annum, although peak rates in different groups exceeded 14,000 per

12 Downs, W. G.: Results in an Infantry Regiment of Several Plans of Treatment for Vivax Malaria. Am. J. Trop. Med. 26: 67-86, January 1946.


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CHART 21.- Incidence of malaria in the 147th Infantry, December 1942 to October 1944, inclusive

1,000 per annum. The rate continued high until suppressive Atabrine therapy was begun again in December 1943. In January 1944, the rate had dropped to 334 per 1,000 per annum, and it continued to decline thereafter (chart 21).

An even more marked reversal than in the Americal Division of species predominance from P. falciparum to P. vivax occurred in this regiment after it left Guadalcanal.

25th Division . - This division landed on Gaudalcanal in late December 1942 and fought through the latter part of the campaign. It soon became heavily infected; in April 1943, the malaria rate reached a peak of 2,335 per 1,000 per annum, although the division was presumably receiving 0.4 gm. per week suppressive Atabrine. The division took part in the New Georgia and Vella Lavella campaigns from July to October. In October 1943, its malaria rate was 1,550 per 1,000 per annum. In December, the division was sent to New Zealand and later to New Caledonia, both nonmalarious islands. Suppressive Atabrine therapy was discontinued in a small group to learn how heavily the division was seeded. In 4 weeks, the rate in this group was 2,091 per 1,000 per annum. Because of the experience already described, no attempt was made to demalarialize this division. Atabrine administration was improved, and the malaria rate declined progressively to 44 per 1,000 per annum in October 1944 (chart 22).

37th Division . - The division arrived on Guadalcanal in March 1943 and was bivouacked in a relatively well controlled area. It. at once instituted an


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CHART 22.- Incidence of malaria in the 25th Division, January 1943 to October 1944, inclusive

effective larviciding program and enforced the use of individual malaria discipline. Suppressive Atabrine therapy was administered by roster, 0.4 gm, per week being given until October 1943, and 0.6 gm. per week thereafter. The division took part in the New Georgia campaign, from July to September 1943, and then returned to Guadalcanal. It was sent to Bougainville in November 1943, where it took part in limited combat for nearly a year.

The malaria rate remained low in this division, never exceeding 250 per 1,000 per annum, and usually being much below this figure. This was partly because the division was bivouacked in a relatively well controlled area when it first came to Guadalcanal, partly because of its early recognition of the malaria hazard, and finally to the energetic and thorough control program that it carried out.

43d Division . - This division bivouacked on Guadalcanal in February 1943 while en route to the Russell Islands and New Georgia. It remained on the latter islands until December 1943, when it was transferred to nonmalarious New Zealand. Throughout its service on the malarious islands, the division had been kept on suppressive Atabrine therapy. During February and March 1944, a small group was taken off Atabrine to learn how heavily the division was seeded. The malaria rate in one company rose to 2,025 per 1,000 per annum, approximately one-half the peak rate of the Americal Division. The monthly malaria rate of the remainder of the division did not exceed 235


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per 1,000 per annum and by July 1944 had dropped to 64 per 1,000 per annum. During all this time, the division was receiving 0.6 gm. Atabrine per week.

    Plasmodium species in troops. - P. malariae was rare among troops in the South Pacific, almost all the cases being due to P. falciparum or P. vivax. The predominant species changed with the progress of each campaign. Early in the campaign, falciparum malaria predominated, but, as control measures progressed and the general malaria rate declined, vivax malaria became increasingly common, until at length it far outweighed falciparum malaria.

This sequence of events is well illustrated by the experience on Guadalcanal. In January 1943, there were twice as many cases of falciparum as of vivax malaria; the two species were about equally common in July, while in January 1944 there were 20 times as many vivax as falciparum cases. The total malaria rates per 1,000 per annum for the island decreased coincidentally from 1,169 in January 1943 to 608 in July 1943 (table 62) and to 200 in January 1944 (table 63). Several factors were responsible for this change. In January 1943, a condition of hyperendemicity existed, with a high transmission rate. Many of the cases recorded as falciparum were probably mixed vivax-falciparum infections in which the vivax had been temporarily suppressed. During this period, too, almost all malaria cases were primary ones, while later on an increasing percentage of them were relapses. Since relapses occur more frequently in infections of vivax malaria, than in falciparum, the proportion of vivax cases increased steadily. The infected troops formed the seedbed for new infections, and as the species distribution of the seedbed shifted, so did the species distribution of new infections. As a result, the percentage of vivax cases increased progressively. In addition, as the overall incidence of malaria decreased, double infections became less common, so that falciparum malaria no longer masked the vivax form. Improvement in Atabrine discipline also decreased the incidence of falciparum malaria.

Prevalence and Decline of Malaria

High malaria rates occurred in the early landings because the importance of malaria was not properly assessed by the troop commanders until it had incapacitated many men and had interfered seriously with the efficiency of their activities. No attempt was made at first to carry out individual protective measures, to enforce suppressive medication, or to combat mosquitoes. In addition, the proximity of infected natives or Japanese provided a seedbed of the disease, and the combat-produced shellholes, foxholes, and ruts greatly increased the mosquito breeding areas. When the importance of malaria was once recognized, elimination of mosquito breeding places, larviciding, enforced use of suppressive Atabrine and of individual protective measures, elimination of infected Japanese, and removal of infected natives all helped to control the disease. The most important of these measures was the elimination of anopheline mosquitoes. While Atabrine undoubtedly prevented the clinical


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appearance of falciparum malaria in many thousands of troops, it merely postponed the inevitable clinical attack of vivax malaria.

Malaria in Enemy Troops

Data on the prevalence of malaria in South Pacific natives have already been given (table 59).

The Japanese suffered more severely from malaria than did the Allied troops. They apparently carried out little mosquito control in the Solomons, although a few knapsack sprayers and small quantities of larvicidal oils were captured. They also had bed nets, a repellent cream whose active ingredient was oil of citronella, a mosquito-repelling punk, quinine, and Atabrine.

Captured medical reports quoted by Harper, Lisansky, and Sasse 13 stated that among the Japanese forces in the Solomon Islands and Bismarck Archipelago the primary malaria rates per 1,000 per annum were 450 in December 1942, 1,098 in January, and 1,637 in February 1943. At Rabaul, New Britain, 32.4 percent of one unit and 22.09 percent of another were malaria patients during February 1943. The total malaria rate for Rabaul and vicinity was 2,503 per 1,000 per annum in April 1943.

The few prisoners captured in the South Pacific were usually emaciated and almost invariably malarious.

ANTIMALARIA POLICY AND ORGANIZATION

At Theater Level

The South Pacific Force under Navy command was a joint U.S. Army, Navy, Marine, and New Zealand group. Commander, South Pacific, was the senior Navy command. The senior Army command within the area was U.S. Army Forces in the South Pacific Area. Island commanders were responsible to ComSoPac and to Commanding General, USAFISPA. On each base, there was an army service command and a naval headquarters, each responsible to the island commander. Commanding generals of divisions, if on established bases, were responsible to island commanders on matters pertinent to that base.

Development of area organization

The initial malaria epidemic among Allied troops occurred on Efate which was occupied in March 1942. During the following month, the military forces on this island experienced a malaria rate of 2,678 per 1,000 per annum (table 61). This explosive outbreak of malaria caused great concern, and an experienced Navy medical officer, Commander Sapero, was sent to Efate in July 1942 to take charge of malaria control measures. An organization had to be created

13 Harper, P. A., Lisansky, E. T., and Sasse, B. E.: Malaria and Other Insect-Borne Diseases in the South Pacific Campaign, 1942-1945; I. General Aspects and Control Measures. Am. J. Trop. Med. 27 (suppl.) : 1-67. May 1947.


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from the ground up; personnel had to be secured, trained, and assigned, directives issued, and supplies obtained.

This organization developed slowly. It required time to procure and train personnel in the problems of entomology, engineering, and malariology peculiar to this area. Only after field trial was it possible to develop a staff for area headquarters and to make those transfers which were essential to build a strong organization. The directives which formed the legal basis of this organization and which established malaria control policy were written and rewritten as new problems were encountered over a period of more than 2 years. The first directive, ComSoPac Serial 301e, was issued on 2 September 1942 and called attention to the existence of a "malaria control unit" available for use on the three bases then occupied, Efate, Espíritu Santo, and Guadalcanal. A group of 10 persons was sent to Espíritu Santo in September 1942 to set up the base malaria control unit there.

Despite the fact that anopheline populations on Guadalcanal were increasing and that malaria was beginning to appear, no malaria control personnel was allowed to start work on that island until mid-November, when the malaria epidemic was in full swing and the anopheline breeding had reached a high level. Such an attitude toward malaria control measures was typical of the prevailing opinion that malaria and malaria control were of minor importance during combat operations. This attitude was largely due to ignorance of the damage that uncontrolled malaria could do to military personnel. The difficulties in establishing malaria control on Guadalcanal despite the obvious need made it increasingly evident that a stronger area directive was necessary. Such a directive, ComSoPac Serial 0094b, was issued on 13 November 1942 and is quoted in part:

Malaria control units, with headquarters at Base Roses (Efate), have been and are being established at various bases in the South Pacific Area. Each unit consists of a medical officer in charge, an entomologist, and laboratory and field technicians who are specialists in problems of malaria control. These units will advise and render service in connection with malaria control to U.S. Army, Navy, and Marine Corps Units and Allied Forces occupying malaria infested islands.

It is the responsibility of the Malaria Control Units to: (1) make epidemiological studies pertaining to malaria, (2) operate laboratories for diagnosis, (3) train personnel from other organizations in laboratory procedures pertaining to malaria control, (4) advise in regard to mosquito control measures, (5) advise in regard to disinsectization of aircraft, (6) make such recommendations to the proper authorities in regard to malaria control as the circumstances require, (7) procure, store and distribute antimalarial drugs for chemoprophylaxis as may be required by the forces at each base.

A laboratory section of a Malaria Control Unit will be established at certain nonmalarious bases. The officers in charge of these units will carry on studies of malaria infected personnel evacuated from malarious bases and will make recommendations with respect to treatment of and malaria control measures pertaining to evacuated personnel. They will also undertake training of laboratory and medical field technicians attached to organizations preparing to enter malarious bases in the special procedures applicable to malaria control.


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Personnel of Malaria Control Units will be attached to the major medical department activity of the base to which the unit is assigned for administrative purposes, berthing and subsistence. The major medical department activity will also provide laboratory facilities for these units.

The Commanders of all bases in which Malaria Control Units are established are enjoined to cooperate to the fullest extent with the officer in charge of Malaria Control Units in order that those units may accomplish their extremely important mission. It is directed that officers in charge of malaria control units be consulted in connection with the selection of sites for camps and airfields and that their recommendations in such matters be given due consideration.

The last sentence of this quotation gave the malaria control personnel on each base a voice in and a responsibility for the location of campsites and other facilities. The malariologists, entomologists, and sanitary engineers made surveys and gave valuable advice concerning the selection of sites which were or could be made relatively malaria free and to the avoidance of highly malarious areas.

A year later this and other orders governing malaria control operations were consolidated greatly strengthening control efforts. Responsibility for the control of insect-borne diseases in all forces was now clearly fixed on one officer with a headquarters unit of mixed Army and Navy personnel. The provision that this officer should recommend "the establishment of Malaria Control Units at bases, and the administration and coordination of malaria and epidemic control" was translated in practice into responsibility to recommend the assignment and reassignment of all malaria control personnel in the area. Similar centralization of responsibility for antimalaria activities on each base was provided by the provision that the senior malariologist at each base should make recommendations and report directly to island commanders. This centralization of responsibility followed a year after the height of the epidemic of malaria on Guadalcanal and at a time when repeated malaria relapses were seriously delaying the return to combat of such combat troops as the Americal Division and the 147th Infantry (charts 20 and 21). Excerpts from ComSoPac Serial 002263, dated 24 September 1943, are as follows:

Organization and Responsibilities

a. Pertaining to the area program of control. A Malaria and Epidemic Control Officer on the Staff of Commander South Pacific has cognizance of all matters pertaining to the control of malaria in all forces in the area. He makes recommendations to the Commander South Pacific for the overall area program of control and recommendations for the establishment of Malaria Control Units at bases, and the administration and coordination of malaria and epidemic control.

An Area Entomologist and an Area Engineer serve to coordinate efforts in their special fields. A Training and Education Officer is responsible for an educational program of practical measures of malaria prevention for all shore-based forces in the Area. He prepares such educational material as malaria training manuals for line and medical officers, and for enlisted men. Posters, films, and other useful training aids are distributed.

b. Pertaining to the control program at malarious bases. The senior Malaria and Epidemic Control Officer of base units is directly responsible to the Island Command for


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an effective program of control, applicable to all forces at the base. He formulates the control program for the base and makes recommendations to the Island Commanders who in turn will require subordinate units to carry out prescribed control measures within their respective commands.

Reports of the senior base Malaria and Epidemic Control Officer are submitted directly to the Island Commander. Copies of such of these as are pertinent are forwarded directly to the senior subordinate commands of the various services at each base, to the Force Medical Officer, Commander South Pacific, the Surgeon, USAFISPA, and Headquarters, Malaria and Epidemic Control.

Base Malaria Control Units are permanently established and serve all forces without service distinction. The units are jointly constituted, being composed of specially trained Army and Navy personnel--malariologists, entomologists, engineers, parasitologists, and laboratory and field enlisted technicians.

The Malaria Control Unit described in this directive, or Malaria Control Group as it was subsequently called, consisted of a malariologist, one or more Army malaria survey detachments, and one or more Army malaria control detachments, or equivalent Navy personnel. The command channels of this group are discussed later (p. 442).

The area organization developed as the area expanded to 11 malarious bases, as the legal basis was broadened, and as the personnel increased from 4 persons in July 1942 to over 750 technically trained personnel and nearly 4,000 laborers in June 1944. This growth made clear the need for an area staff which was developed in the following order of appointment: An area malaria and insect control officer; an area entomologist; an Army liaison officer, an area training and education officer; an area administrative assistant; an assistant malaria and insect control officer; an area engineer and two filaria survey officers.

Responsibilities and duties

The duties and responsibilities of the area organization were as follows:

1. It served all Allied Forces in the area.
    2. It formulated area directives which were issued by ComSoPac and Commanding General, USAFISPA, and which defined and gave authority to insect and rodent control policy, organization and function.
    3. It made recommendations for the procurement, assignment, and transfer of all personnel assigned to insect control activities.
    4. It provided technical and supervisory assistance to the various base and division malaria and insect control groups.
    5. It was responsible for the control work of the base groups and established a uniform system of reports and inspections.
    6. It recommended allowances and provided for procurement and distribution of malaria control equipment and supplies.
    7. It provided an areawide educational and publicity program of malaria and insect control for all personnel, and special information for line officers, medical officers, and for personnel assigned to malaria and control work.


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CHART 23.- Malaria and Insect Control Organization, South Pacific Area, 1 June 1944

8. It made personnel and equipment available for special problems of malaria control such as airplane application of DDT solutions and spraying of bed nets with DDT, and for problems concerned with filariasis, mite-borne typhus, dengue, and rodent control.

Chart 23 shows the personnel of the area organization and the distribution of base and division groups. Letter orders authorizing all necessary travel to malarious bases were given to the area staff. Some member of the headquarters staff made a complete circuit of the malarious bases every 4 to 8 weeks to keep in touch with local work and needs. The area entomologist and engineer offered technical assistance and advice to the corresponding officers in each base unit. Distribution of technical information was also accomplished through a newsletter and through special publications such as synoptic keys to mosquitoes. Uniform methods of reporting information were adopted for all base reports as well as for area reports.

Procurement and assignment of technically trained personnel . - Table 65 describes the personnel engaged in insect control work as of 15 May 1944. The technically trained personnel comprised medical officers, entomologists, parasitologists, sanitary engineers, and enlisted personnel of the control and survey detachments. They formed the Base and Division Malaria and Insect Control Groups. As of 15 May 1944, this personnel comprised 128 officers and 643 enlisted men, divided as follows: Army, 452; Navy and Marine, 282; New Zealand, 37.

Technically trained Army malaria control personnel was provided by the War Department in three categories: Malariologists (medical officers), malaria survey detachments, and malaria control detachments.


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TABLE 65.- Malaria and insect control personnel, South Pacific Area, 15 May 1944

Army malariologists arrived as casual officers. Almost all of these officers had taken the course in tropical medicine at the Army Medical School, and the majority had had field work at the Army school in Florida or Panama. They were attached to Headquarters, Services of Supply, South Pacific Area, and then ordered on detached service to the various bases and divisions. There were 21 Army malariologists in the area: 2 lieutenant colonels, 8 majors, and 11 captains. One Army malariologist was on the area malaria control staff, 6 were senior base malariologists, 6 were division malariologists, 1 was assigned to the Office of the Chief Surgeon, USAFISPA, 1 to Headquarters, XIV Corps, and the remainder acted as assistant base malariologists.

There were 17 malaria survey detachments and 20 malaria control detachments within the area, as of 1 June 1944. The officers of these detachments all met the basic technical requirements for their specialty. The enlisted men were untrained at time of assignment but were usually of high caliber and rapidly became competent technicians under the guidance of their officers. There would be great advantages if in the future these enlisted men could have a period of formal training at Army medical centers or at one of the Army malaria control schools.

Navy malaria control personnel was procured through the Navy Department either from the Malariology School of the Naval Medical School, Bethesda, Md., or from Navy replacement pools or other organizations within time South Pacific. The usual Navy malaria control team consisted of one officer, an entomologist, and from three to five enlisted men. Each Marine division


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was provided with a larger team (called an epidemiology unit) of 3 officers (malariologist, entomologist, parasitologist) and 12 enlisted men. An engineer for this team was provided from the sanitary section of the naval construction battalion which was attached to each Marine division. Enlisted men from Bethesda were well trained in laboratory diagnosis and in elementary field procedure. Several Navy officers experienced in rodent control were obtained from organizations in the South Pacific. Navy warrant and Hospital Corps officers were also secured locally to administer malaria control personnel and supplies on larger bases.

The Navy malariology teams were often broken up and assigned to Army-Navy or all Navy groups to meet the needs of a local or island situation. This was in contrast to the policy of assigning Army units intact and resulted in a valuable flexibility.

Procurement of labor and equipment. - Skilled and semiskilled labor was needed for semipermanent mosquito control work which required the operation of heavy equipment such as bulldozers and draglines and special skills such as those of a dynamite expert. Almost all such skilled labor and heavy equipment were obtained from naval construction battalions or from the Army Corps of Engineers.

An entire naval construction battalion was assigned to malaria control work on Guadalcanal in May 1943 on recommendation of the theater malariologist. Subsequently, sanitary sections for malaria control work were organized in all naval construction battalions.

Unskilled labor was recruited from three sources: Army medical sanitary companies, natives, and troop unit antimalaria details. The first Army medical sanitary company arrived about mid-1943 and was assigned to Guadalcanal. Subsequently, nine such companies arrived of which eight were assigned to malarious islands on recommendation of the theater malaria and insect control headquarters. It should be emphasized that every medical sanitary company on a malarious island in the South Pacific worked full time at malaria control. Credit for withstanding the pressure to assign these units to other work must be given to the Surgeon, USAFISPA.

Native labor was scarce and was strenuously competed for by both combat and service units. Usually a certain proportion were assigned by the Island Command headquarters to malaria control work.

The work of skilled and unskilled labor is described on pages 445 and 487.

Supplies and equipment . - There were acute shortages of all antimalaria supplies and equipment in 1942, of which the most important were Atabrine, mosquito repellent, insecticide and knapsack sprayers. In this early period, the area malaria control organization advised on allowances and was responsible for the establishment of quotas and distribution of those items in which shortages were acute. Excerpts from the pertinent directive14 follow:

14 Circular Letter No. 15, Headquarters, Services of Supply, South Pacific Area, 13 May 1943.


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1. Central procurement, distribution and issue of insecticides, pest control supplies and equipment for all Armed Forces located in the South Pacific Area (less those located in the Samoan Group) has been assigned to the Army Services of Supply by ComSoPac.
    2. Service Command Quartermasters, *   *   * in cooperation with the Base Malaria Control Officers, will receive, store, and distribute the above supplies to all Armed Forces at each base. Navy Supply Officers, Marine Quartermasters and New Zealand Supply Officers may obtain their stocks in bulk from Base or Service Command Quartermasters at each Base, by requisition.

*                    *                     *                     *                      *                    *

5. The use of insecticides and insect repellents within the South Pacific Area will be governed by Instructions issued by each base malaria, control officer.

Transportation was often a serious problem. Each malaria control group was responsible for a territorial coverage which averaged about 20 square miles, often in the shape of a long narrow beachhead. In addition to distributing their own survey and control crews to all parts of this territory, most groups transported 50 to 100 native laborers to and from work each day and hauled labor details. They also did power spraying, hauled gravel, and did other work requiring vehicles. The increased number of vehicles which were finally authorized for malaria detachments and for medical sanitary companies were adequate. A special theater directive provided transportation for malariologists.

Liaison

Since this was a joint service organization, no liaison was needed between branches of military service or with Allied Forces. There were contacts with the civil population on New Caledonia and on Efate chiefly in connection with antimosquito operations. These were ordinarily easily handled through official channels. The assistance of the parish priest was sought, and generously given, when dengue carrying mosquitoes were found breeding in flowerpots and other receptacles used for decorating graves in the cemetery.

Local or Island Organization and Procedure

The work of the malariologist

The command basis for the work of the island malariologist has been described (pp. 435, 436). By these directives, the senior malariologist at each base eventually was made directly responsible to the island commander for formulation of a program of control applicable to all forces--Army, Navy, Marine, and Allied--and for recommendations to make this program effective. The commanding officer of each subordinate organization on the island was responsible for all malaria control activities within amid adjacent to this bivouac site. Reports and recommendations of the senior base malariologist were submitted directly to the island commander, who, in turn, required the subordinate commanders to carry out prescribed control measures. This chain of command was unusual in that it did not conform with the ordinary channels through the


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CHART 24.- Island organization and command channels, Joint Army-Navy malaria and insect control

commanding officer of service command or through the Commander, Naval Advanced Base.

This latter point may be expanded by citing the problem of Guadalcanal where the malaria control organization was a mixed one of Army and Navy personnel and where the first island malariologist was a Navy officer, subsequent ones being Army officers. The question arose: Should command channels through Commander, Naval Advanced Base, be utilized when the senior malariologist was a Navy officer and should these channels be changed to go through Commanding Officer, Service Command, when the senior malariologist was an Army officer, or should both command channels be utilized since this was a mixed service group? The solution was direct reporting to the Island Command with copies to subordinate commands.

The organization of the Army-Navy malaria control personnel on a typical island base is shown in chart 24. A mixed Army-Navy group was developed on most islands. The variable size of the Navy units was particularly advantageous for small bases where only one or two officers and a few enlisted men were needed and where the Army units of fixed size were too large.

Chart 25, Guadalcanal Malaria and Insect Control Organization, is presented as an example of organizational development on islands large enough to require two or more malaria control groups. (The term "Malaria Control Group" is used to designate a working organization comprising a malariologist,


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CHART 25.- Guadalcanal Malaria and Insect Control Organization

a malaria survey detachment, and a malaria control detachment.) The Island headquarters was not provided for by any table of organization but developed to fill a need for overall supervision on larger bases. Modifications of the headquarters section, diagrammed in chart 25, were established on Efate, Espíritu Santo, New Georgia, and Bougainville.

The malaria control personnel on most bases formed a joint Army-Navy group who lived under one roof and worked together in one area. Two-thirds of the groups were attached to Army or Navy hospitals for quarters and rations, one-third to Navy advanced bases or Army service commands. Three groups set up independent housekeeping with a medical sanitary company assigned to malaria control work. This had distinct advantages, among which was a time for meals favorable for field work.

The position of the malariologist in this organization was an ambiguous one which can be explained best by saying that he was a staff officer whose duties often required the assumption of command responsibility. This was evident in his relations with assistant malariologists and with personnel of survey detachments, control detachments, and sanitary companies. He selected their locations, directed their work, and initiated or approved recommendations for promotion. This assumption of command responsibility functioned well because of a general willingness to cooperate and because the high command fostered such a situation by directives quoted previously which made the ma-


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lariologist responsible for all insect control activities on a base. However, the malariologist had no legal command authority over the malaria detachments and medical sanitary companies which were small, independent commands. In a long-range program, this officer should have command authority corresponding to his responsibility.

The duties of the malariologist included:
    1. Formulation of an effective program of mosquito control, utilizing the advice and assistance of specialists, the entomologist, the parasitologists, and the engineer.
    2. Integration of the work of the survey detachment, the control detachment, and labor.
    3. Estimation of need for and requisition of personnel and supplies to execute the program.
    4. Development of an effective malaria training and educational program.
    5. Preparation of directives pertaining to malaria discipline and the making of spot inspections for violations of malaria discipline.
    6. Consultation and recommendation in regard to the selection of sites, for camps, airfields, bivouac and maneuver areas.
    7. Segregation of natives.
    8. Recommendations concerned with the institution and discontinuance of suppressive medication.
    9. Supervision of disinsectization of airplanes and ships and other measures to prevent the dissemination of disease.
    10. Preparation of reports of the malaria situation on his base or in his division area, including especially statistics regarding malaria incidence, status of malaria discipline, entomological and climatological data, work of control units, activities of the training program, status of antimalaria supplies and of personnel engaged in control work, and recommendations.

The first work was done where troops were concentrated. Speed in instituting control measures was most important in occupying a new base. Initial surveys were done rapidly and more thorough work came later. Larviciding and other temporary work, such as clearing of paths to facilitate oiling, were usually initiated coincidentally with the first survey.

The initiation of semipermanent work depended on the size of the troop population to be protected, the period the area was to be occupied, and the available labor and equipment. As soon as surveys were completed, a list was prepared of semipermanent control projects with detailed estimates of labor and equipment. These projects were listed in order of priority and were initiated directly if they were within the scope of the malaria control personnel under the jurisdiction of the malariologist. Larger projects requiring special equipment and labor were submitted through proper channels to the commanding general for approval and for assignment of the needed equipment and personnel. These projects competed with other high priority work, such


445

as roadbuilding, airfield construction, and erection of hospitals. Presentation had to be clear and concise and had to include an adequate justification for priority.

The need for continuous integration of the work of the survey and of the control units was recognized rapidly. In wartime practice, survey and control work were initiated simultaneously and continued to be interdependent.

The malaria survey and the malaria control detachments

The Army malaria survey detachment consisted of 2 officers and 11 enlisted men, all technically skilled, and charged with entomologic and parasitologic work to aid the control of malaria and all other insect-borne disease.

The entomologist and his enlisted men furnished information about the breeding of mosquitoes and other insects, their biology, and relations to disease. This information was always accompanied by recommendations as to specific control measures. The work was continuous and was recorded on maps and other forms so as to give a clear and continuous check on the effectiveness of control.

The parasitologic section of the survey unit furnished information about the incidence of malaria and other parasites in natives, in U.S. troops, and in Japanese prisoners and recorded this knowledge so as to aid both the planning and the evaluation of control work.

The Army control detachment comprised an engineer and 11 enlisted men and was responsible for planning, executing, and maintaining all insect control measures based on the findings of the survey detachment; for supervision and correlation of all labor and equipment for this work; and for maintenance of suitable records to give a continuous and clear picture of control activities.

The enlisted personnel performed a variety of duties, according to the local situation. These men were most economically and efficiently employed as supervisors. Occasionally, on large bases, an entire control team was made responsible for a special project such as work on flume and culvert maintenance. Additional enlisted personnel were assigned to work with dynamite or bangalore torpedo ditching crews. Men were trained to operate bulldozers, draglines, and other heavy equipment. On islands where airplane spraying of DDT solutions became an important control measure, crews of one to six men were assigned to mix DDT solutions and to service the spray apparatus installed in the planes.

Table 66 shows the average number of personnel available for the work of the malaria control units during the 6-month period from December 1943 to June 1944. The engineer was responsible for the work of these laborers except that of the troop antimalaria details. Thus, on the larger bases, each engineer had from 100 to 250 men, exclusive of troop units, working under his general supervision.


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TABLE 66.- Personnel available for work of malaria control units, South Pacific Area 1

Troop Unit Antimalaria Organization

From the first, antimalaria details were expected to do the larvicidal work in their own areas. The assignment of men to oiling details in 1942 and the early half of 1943 was irregular and depended on personal arrangements between the island malariologist and each commander. In September 1943, an areawide directive, ComSoPac Serial 01619, dated 13 September 1943, ordered the formation of a mosquito control squad in every battalion. A subsequent directive, ComSoPac Serial 02158, dated 19 October 1944, ordered the formation of an antimalaria detail in each company, battery or similar unit. This detail consisted of one noncommissioned officer and two enlisted men per infantry company or a proportionate number for other units. In nonmedical units, these details were made up of nonmedical personnel. These details were responsible for all insect control work within the region occupied by their units, and their work was checked by technicians from the base or division malaria survey detachment described previously.

These antimalaria details worked effectively in all situations except those of frontline combat. It was not only impossible for most antimalaria details to do antimosquito work under combat conditions, but these personnel were as fatigued as their comrades at the end of the combat period and so further postponed this work. To remedy this situation, temporary spray teams were formed in combat regiments and are described in the next section.


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Division Malaria and Insect Control Organization

The Division Malaria and Insect Control Group comprised the division malariologist, a malaria survey detachment, and a malaria control detachment totaling 4 officers and 22 technically trained enlisted men. This group was attached to the division over and above its established allowance for Medical Department personnel. They performed the same functions for the division as did the base malaria and insect control group for each island base, with the additional duty of providing antimalaria protection during the periods of active combat. This resulted in less emphasis on specialization and more emphasis on flexibility, with every man trained to aid in all phases of a simple anti-mosquito program.

It was the duty of the division malariologist to provide plans for the control of malaria, dengue, mite-borne typhus, and other insect-borne diseases during a period of active operation. The final plan, selected from several prepared in advance, was determined by the particular military situation.

An important feature of all such plans was the provision for a pool of trained men to do temporary insect control work behind the lines during combat periods. This pool of personnel was obtained by drawing one man from each antimalaria detail and adding a technically trained nucleus from the attached survey and control detachments. In most plans, this personnel was split into four temporary spray teams, of which one was attached to division headquarters and one to each of the three regimental headquarters. The temporary spray team went ashore with the division or regimental headquarters to which it was attached and began work. Fly control was done by spraying unburied bodies with 5-percent DDT solution or 1-percent sodium arsenite solution. Straddle trenches, pit latrines, and other sources of fly breeding were treated similarly. Mosquito control measures were carried out around headquarters, medical facilities, supply dumps, and along communication lines, (See appendix A, p. 582.)

Malaria Control Labor

Unskilled labor was obtained from Army medical sanitary companies and natives. Each Army medical sanitary company consisted of 3 officers and 109 enlisted personnel. These companies provided their own messing facilities and were authorized 15 to operate nine vehicles and other suitable equipment. They were assigned to island commands and were employed as directed by the malariologist in conjunction with antimalaria work. There were eight medical sanitary companies used only for malaria control within the South Pacific Area as of 1 June 1944, located as follows: Four companies on Guadalcanal; one each on Russell Islands, Munda, and Bougainville; and one divided company

15 T/O&E 8-117, Medical Sanitary company. 13 May 1944.


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with a platoon on Green Island and a platoon on Emirau Island. They rapidly developed an understanding of the problems of malaria control and facility in necessary procedures. Enlisted men who showed aptitude were trained in the operation and maintenance of heavy equipment, in dynamite work, and in mosquito survey work. These troops were of great value as a constant source of experienced labor. Their activities included larviciding, application of residual spray, hand ditching, and similar work.

Natives were employed on nearly all bases. The decision to utilize this source of labor was made early in the campaign with the knowledge that these local inhabitants constituted a potential seedbed of malaria and filariasis. The malaria control organization attempted to minimize this health hazard by segregation and by other means described in the section on malaria control measures. Laborers worked in sections of 25, each with its own native sergeant. The total number of imported Melanesian laborers on all bases was over 6,000 in 1944. About 600, or 10 percent, worked daily on malaria control during the period of maximum activity in the theater.

Airplane Spraying Arrangements

Arrangements made by the malaria and epidemic disease control organization for the accomplishment of airplane spraying varied on different bases. In one respect, however, they were uniform; that is, all spraying was done on a scheduled basis and because of known need for larvicidal work, with the exception of spraying done on a purely experimental basis for evaluation of equipment. Only small aircraft were routinely used. Frequently, the equipment used and operating arrangements resulted from informal arrangements, and much of the spray equipment was fabricated at airplane maintenance shops. On most bases, pilots were assigned to the malaria control organization for operational control, a most important factor in the accomplishment of efficient airplane spraying. The arrangements eventually worked out for airplane spraying on Guadalcanal may be considered representative of this work in the South Pacific.

All regularly scheduled and special flights were under the control of the Island Command entomologist who briefed the pilot on the area to be covered and arranged for loading the airplane with insecticide. The pilot arranged for operational clearance from the field where the plane was based and from the field from which operations were to be carried out. Usually, the field nearest the site to be sprayed was selected for use, in order to minimize the time required for return to the field for reloading. Frequently, abandoned airstrips were used until this practice was forbidden because of the lack of emergency equipment. Aircraft were serviced by means of a mobile service truck developed and equipped for the specific purpose. In practice, the use of aircraft without radio equipment proved an advantage because of priority in landings and take-


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offs from busy fields. Experienced pilots, properly briefed, needed no ground guides other than terrain or vegetative features in order to accomplish thorough coverage.

Other Military Agencies Engaged in Antimalaria Work

Skilled labor for malaria control work included dragline and bulldozer operators, dynamite experts, carpenters, and welders to make flumes and culverts. Such skilled personnel and heavy equipment were obtained chiefly from naval construction battalion personnel, and in small part from the Army Corps of Engineers.

In May 1943, the need for large-scale mosquito control work on Guadalcanal became so urgent that the entire 63d Naval Construction Battalion was ordered by ComSoPac to malaria control work at that base. The personnel of this battalion rapidly became acquainted with malaria control problems and techniques and accomplished an extraordinary amount of semipermanent control work over the entire base.

The formation of sanitary sections in all naval construction battalions for use on malaria control work was authorized by a series of directives issued in July and August. These directives ordered each naval construction battalion to form a sanitary section of 110 enlisted men and to provide specified equipment for work on malaria and epidemic control projects under the direction of base and division (Marine) malariologists. Equipment assigned to each sanitary section included one dragline crane, one tractor with bulldozer blade, and seven trucks. Since there were about 20 naval construction battalions on malarious bases in the year subsequent to this order, these directives made available to malaria control a potential total force of over 2,000 men and more than 20 bulldozers, 20 dragline cranes, and 140 vehicles. Actual compliance with these directives furnished about 500 men, 10 to 15 bulldozers, and 8 to 12 dragline cranes daily for work on malaria control projects during the 8-month period, November 1943 to June 1944.

Despite outstanding work by many of these battalions, compliance with these directives was usually delayed and incomplete. Work often was done too late to forestall an initial outbreak of malaria and seeding of troops. This was due to high priorities for airfields, roads, harbor, and storage facilities. Requests for diversion to malaria control of 10 percent of men and equipment often seemed unreasonable to the officers responsible for major construction projects.

Certain faults were inherent in the sanitary section of the construction battalion as originally conceived. Construction battalion personnel comprised for the most part highly skilled labor with technical ratings and with only few unskilled workers. It was wasteful and damaging to morale to use skilled labor for unskilled manual work. Wherever possible, the use of skilled construction battalion labor was limited to the use of heavy equipment and to other skilled jobs while unskilled manual work was done by native labor.


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The use of Army engineers for malaria control was authorized 16 as follows:

"The Corps of Engineers is charged with the responsibility for the execution of mosquito control work on real property. This includes such measures as drainage, filling, larvicidal programs, and screening."

The number of troops in the Army Corps of Engineers in the South Pacific Area was small, as compared with the number in the naval construction battalions. The use of such troops for malaria control projects was subject to the same delays encountered with naval construction battalion sanitary sections with the added handicap that no set percentage of troops in the Army Corps of Engineers was directed to do malaria control work. A few of these troops did excellent work on insect control projects, but the total was small.

The practice was begun during 1944 of submitting consolidated estimates for all base malaria control projects to the commanding general, with the request that these projects be assigned to heavy equipment units. This resulted in the division of these projects between Army engineer units and naval construction battalions. Such projects were well prosecuted.

A large share of semipermanent work was done with borrowed equipment which was maintained and operated by personnel of malaria control detachments and medical sanitary companies. Such equipment which was in great demand was obtained by a process of barter and exchange, the details of which were best known to Army supply sergeants and Navy warrant officers.

Thus, malaria control personnel on Guadalcanal operated an average of 10 bulldozers, 2 draglines, and several disk harrows throughout 1944, and similar personnel on Espíritu Santo and Bougainville operated about one-half of this amount. of equipment. A few experienced operators of such equipment were found in the various malaria control detachments and others were trained. The great majority of all semipermanent drainage work done in the early months of occupation on several island bases was accomplished in this extralegal manner. These experiences led to a recommendation to the War Department, which was approved by Headquarters, Services of Supply, South Pacific Area, to add a limited amount of heavy earth-moving equipment to the table of organization and equipment of medical sanitary companies. This recommendation was rejected on the ground that medical sanitary companies did not have time necessary maintenance crews and facilities to service such heavy machinery. This objection was theoretically valid; in practice, however, such equipment in the hands of malaria control units had an excellent record for days worked per machine per month and for rapid repairs when needed. 17

16 War Department circular No. 223, 21 Sept. 1943.
17 It is still our opinion that some plan of assigning such equipment to a malaria control organization is essential if semipermanent control work is to be accomplished during the early months on a new base--Authors' Note.


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ANTIMALARIA ACTIVITIES

Training, Information, and Propaganda

The training and education program was planned to reach every officer and man in the area on a level consistent with his responsibility. This program fell into two parts: (1) The work of the area headquarters staff which developed the necessary directives, provided manuals, posters and other educational aids and conducted a small area training center; and (2) the work of base and division malaria control groups which directed the mass education program.

The area stall prepared six pocket-sized manuals, three on malaria and one each on dengue, filariasis, and rodent control. The three manuals on malaria were written respectively for medical officers, for line officers, and for enlisted personnel. About 500,000 copies were printed locally to provide one for every officer and man in the area. The area staff included an artist, who, over a 2-year period, produced 15 posters, a monthly pinup calendar, and a weekly cartoon for the Sunday edition of the local mimeographed paper. "Malaria Moe" and the Frank Mack versions of a pinup girl and of an anopheline mosquito were found in nearly every tent and quonset hut in the area. Posters were reproduced in numbers to supply one large and one small size for every 200 men. One calendar was printed monthly for every five men.

A library of malaria control films was obtained and circulated to all base and division groups which arranged for command showing of the more important ones. Only two films were considered adequate, a "Snafu" film on malaria and a film produced by the Army Air Corps, TF1-3343. Such excellent results were obtained from the few satisfactory films that were available that it is to be hoped that more and better training films will be prepared for these subjects.

A monthly newsletter was found to be a most successful method of disseminating current information to malaria control officers, hospitals, and base and division surgeons.

An area training center in malariology and other insect-borne diseases was established first on Efate and later on Espíritu Santo. It began late in 1942 with small classes of three to five officers for 2-week periods. The students at this school included all newly arrived malariologists and such troop unit malaria control officers as could be spared from their organizations. The school was located on the grounds of a large hospital which had a high census of patients ill with malaria and other tropical diseases and who were available for clinical and parasitologic study. The medical staff of the hospital aided the area malaria control staff in the teaching program. Adequate parasitologic and entomologic collections were built up and a small but good library was obtained. Thirty malariologists, or more than two-thirds of those


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who worked in the area, attended these schools as did a larger number of troop unit malaria control officers.

The training program on each island or base was divided into three parts: An apprenticeship system for newly arriving personnel of malaria control and survey detachments; a short school for troop unit antimalaria details; and a simple educational program for every man in the area.

The apprenticeship system was devised to meet the needs of incoming malariologists, entomologists, parasitologists, engineers, and the men of their detachments, a few of whom were experienced in the problems peculiar to the South Pacific Area. This apprenticeship period lasted from 1 to 3 months. The teaching staff consisted of the entire personnel of a veteran group, and the curriculum was the daily work of this established group. After a short time, the newly arrived personnel were assigned a small area and were made responsible for all phases of antimalaria work therein, before being given a completely independent assignment.

It was often possible to place six or eight men of a control unit with a naval construction battalion or Army engineer company, where they rotated through a program of work with dragline crew, transit crew, dynamite gangs, and heavy maintenance section.

The training of enlisted personnel as technicians qualified to read blood smears for malaria was one of the urgent problems in the early period. The first school for technicians was started at Efate, using as instructors corpsmen who had been trained at the Naval Medical School. From 50 to 100 routine thick-blood smears were examined each day by these corpsmen and were available for teaching purposes (fig. 54). Similar schools were established on Espíritu Santo, Guadalcanal, and other bases as soon as malaria control groups arrived. Students were trained either singly or in small groups. Over 450 technicians were trained in the first 2 years of this work with an improvement in malaria diagnosis throughout the area to the point where over 95 percent of all cases were confirmed by the laboratory.

The School for Troop Unit Anti-Malaria Details was designed to teach the elements of larviciding and other control measures to the men who comprised these details in each company. This activity was initiated by ComSoPac Serial 01619, issued on 13 September 1943 and revised on 19 October 1944 by ComSoPac Serial 02158.

An effort was made not only to show how to control malaria but also to explain the rationale of this work, thus creating a nucleus of informed officers and men in each battalion and company. An average class consisted of 10 to 15 students. The officers and selected enlisted men from base and division malaria control groups comprised the faculty. The period of instruction was usually 2 to 3 days. The presentation of subject matter was elementary. The unit medical officer was required to attend because he was expected to use this type of presentation in his talks with the men of his


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FIGURE 54.- Recording results of microscopic examinations of blood smears.

organization. Emphasis was placed on practical fieldwork. Between 4,000 and 5,000 officers and men attended these schools during the first 2 years of their activity.

Educational Program for All Personnel

All of these programs were concerned with personnel engaged in full- or part-time insect and rodent control work. The basic educational program, to be described, aimed to impress every man with the importance of malaria and with how he might protect himself from mosquitoborne disease. Few troops had had any education in malaria before arrival in the area. The need for this educational work was so apparent that programs were initiated almost simultaneously on several staging bases including the Fiji Islands, New Zealand, and New Caledonia. The value of these early uncoordinated efforts was immediately evident. At the same time, there was apparent need for a uniform area training and education program, for approved training manuals, and for a publicity program employing the radio and other educational aids. A theater directive was first issued in mid-1943 and was revised by ComSoPac Serial 02158, 19 October 1944. An extract follows:

Training Program in Malaria Control

1. Unit Commanders will allot in the training schedules sufficient time for the proper instruction of their troops in the principles of malaria prevention.


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2. Lectures will be given to small groups of men by their respective medical officers. These lectures will cover the following:
        a. Military importance of Malaria.
        b. Nature of Malaria, How Transmitted and Effects.
        c. Individual Protective Measures, Conditions in Which Each is Applicable, Especially in Combat.
            Repellents,
            Use of Ordinary Clothes for Protection.
            Spray-killing of Adult Mosquitoes.
            Bed Nets.
            Atabrine Suppressive Therapy.
            Avoidance of Unnecessary Exposure.
        d. Control of Mosquito Breeding.
        e. Man-made Malaria--How to Avoid It.

3. All personnel will be given initial instruction in prevention of malaria by lectures and motion pictures as soon as practicable. Subsequently, a review of the subject will be carried out at least once a month.

4. Additional instruction will he given to officers and non-commissioned officers, or petty officers, covering especially the selection of campsites, the hazard of natives as a source of malaria, and the enforcement of precautions under varying field conditions. Emphasis will he put on the responsibility of officers and non-commissioned officers for good "Malaria Discipline" and its importance to military success. Arrangements may he made to have members of Base Malaria Control Units assist in this program.

5. To aid in this program permanently based Malaria Control Units (or Island Surgeons) will issue the following malaria training manuals:
        All Medical Officers:     MTM No.1. Prevention of Malaria in Military and Naval Forces, SPA.
        All Officers:                  MTM No.2. Military Malaria Control, in the Field.
        Enlisted Men:               MTM No.3. Malaria. Mosquitoes, and Men.
Movies, additional literature, posters, and other material will also be made available by Malaria Control Units.

6. Every unit will periodically conduct field exercises in the practical application of antimalarial measures. On maneuvers, these measures will be standard procedures.

Arrangements were made for brief radio announcements on each base every evening which reminded listeners to roll down sleeves, to use repellent, and to take other precautions. The radio stations were known as the Mosquito Network, and on Guadalcanal a program of recorded music known as the Atabrine Cocktail Hour began each evening with a plug for malaria or dengue control.

Parasitological Survey Activities

The parasitology sections of the malaria survey units participated in the educational and inspection activities of the malaria control groups. In addition, they were charged with the responsibility of seeing that all blood smears were read correctly. Upon request, they trained technicians for the hospitals, sickbays, amid other installations where blood smears were examined. They also made periodic checks on the accuracy of the diagnoses made by these installations. They provided a microscopic diagnostic service for dispensaries, sickbays and other installations which were unable to examine slides them-


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selves. In 1943 alone, over 75,000 slides were read on Guadalcanal. The parasitology sections carried out surveys of malaria and filariasis among natives and others. The parasitologists also collected and compiled statistical data on malaria incidence in the troops.

Entomologic Survey Activities

The personnel and organizational structure utilized for entomologic survey activities in the South Pacific Area were discussed previously (chart 25). In actual practice, this organization was an exceedingly flexible one, adaptable to peculiar circumstances and problems as the need arose, and Army malaria survey detachments were seldom used as distinct and independent units. Responsibility for survey work was assigned on an area basis, with an entomologist, either Army or Navy, in charge, and personnel from either or both of the services detailed as needed or available. An area entomologist was on the staff of the area malariologist to provide overall coordination of the work. Island entomologists were designated to coordinate the survey work on the larger bases; namely, Bougainville, Espíritu Santo, and Guadalcanal.

In general, within a designated area, the entomologist and his crew were responsible for surveys to determine the incidence, distribution, and biology of arthropods of medical importance; for recommendations as to the areas requiring control operations, their proper treatment, and relative importance; for routine inspection surveys to evaluate the effectiveness of control operations; and for maintenance of appropriate records of insect populations and their fluctuations in response to control activities or other factors. Special investigational projects were undertaken as times permitted or the need arose.

The duties of the area entomologist were to advise the area malariologist concerning the broad aspects of the entomologic work, to aid in the procurement of entomologic supplies, and to assist base entomologists in the establishment of survey procedures. A similar relationship existed between the island entomologists and the malariologists of the respective bases. In no instance were these command positions, and the personnel assigned to them acted merely as technical advisers and coordinators. The value of this type of coordination was recognized, particularly since it facilitated the dissemination of ideas and information of value to the general program. The area entomologist prepared and distributed a monthly newsletter which included pertinent entomologic and engineering data. Monthly meetings of the entomologists on Guadalcanal were held, and these were occasionally attended by entomologists from Tulagi. These meetings were conducted in the best entomologic traditions and greatly facilitated the problem of coordinating survey work on the base.

Field survey work within an assigned area was usually conducted by from 7 to 10 enlisted technicians in addition to the officer in charge. The senior noncommissioned officer was in direct charge of both field and laboratory work,


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2 or 3 men were usually detailed to insectary and laboratory activities, and the remainder to field surveys. Area assignments varied in size, depending upon the complexity of the problems encountered and the terrain involved. They usually consisted of from 10 to 45 square miles of territory. The entomologist and the senior noncommissioned officer were necessarily familiar with the entire territory in a general way, and field scouts were expected to become acquainted with their assigned subareas in a detailed fashion.

In actual practice, no sharp distinction could be made between initial exploratory surveys and routine inspection surveys, since the one gradually evolved into the other. Under ideal conditions, initial surveys of a territory followed critical inspection of maps and aerial photographs of the area. Unfortunately, during the early phases of the South Pacific campaign, this was seldom possible. The lack of adequate maps for malaria control activities reflected the situation from the tactical standpoint. There were no good maps of Guadalcanal before the invasion, nor was that deficiency corrected throughout the combat period. Initial surveys were often sketchy and incomplete, either because of combat conditions, inadequate personnel, or other factors. The objective of the initial surveys was to determine as quickly as possible the location, extent, and description of actual or potential mosquito-breeding places; the records of current adult and larval populations; and the locations of native villages or other possible reservoirs of tropical diseases. As survey work progressed, the accumulated information was used to draw up detailed recommendations for a control program. As the control program developed, the survey activities became progressively more routine, but field survey personnel were at all times enjoined to report on the necessity for new projects to correct potentially dangerous situations, as well as the need for maintenance work of any kind. Because of the ever-changing situations on most bases, initial survey activities were never really terminated.

Routine survey activities were primarily aimed at improving the larvicidal program. Various attempts were made to evaluate the control program through sampling the adult mosquito population, but these were not generally successful. As indicated previously in the discussion of the habits of A. farauti, all attempts to estimate the population of this species through counts of adults in daytime resting places failed, or were of very limited practical value. The routine operation of mosquito light traps seldom produced Anopheles in sufficient numbers to be of significance and in areas of relatively low populations seldom produced any specimens. Night catches of mosquitoes were fairly reliable as a measure of the population but were time consuming if properly carried out. For these reasons, sampling of the larval population was usually the method of evaluating the control program. In addition to supplying a more sensitive measure of population fluctuation, larval sampling permitted immediate application of control measures.

It was recognized early in the work in the South Pacific that close coordination of survey and control activities was necessary to attain the highest degree


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of efficiency in the approach to malaria and epidemic disease control. This was particularly true with respect to the larvicidal program. In order to facilitate coverage of all available water surfaces, survey crews routinely maintained maps showing the location of water catchments and the results of larval population sampling. Since primary emphasis was placed on malaria control, the location of A. farauti breeding foci was indicated on the map in red, the density of the population being shown in terms of a fraction, the number of larvae over the number of dips taken. Thus 150/60 meant that a total of 150 larvae was taken in 60 dips. Populations of culicine larvae were similarly recorded in blue. These data were recorded daily on large-scale wall maps covered with a transparent overlay.

At the end of each checking period, usually 1 week, the data were transferred to record-size maps, and the overlay was cleaned off before the results of the next survey were added. Control crews consulted the map daily and guided their efforts accordingly. This system permitted personnel concerned to note at a glance the situation throughout the area and enabled the entomologist and engineer to follow, week by week, the progress being made in the elimination of "hot spots." These data gave an accurate picture of the potential malariousness of an area long before that information could be derived from reports of incidence of the disease.

Antimosquito Operations

The story of mosquito control operations in the South Pacific is a story of improvisation and salesmanship. Under the stress of wartime conditions, it was necessary to work under the handicap of critical shortages of personnel and equipment. Much of the equipment available during the early phases of the work was ill adapted to the job and had to be discarded or constantly repaired. Attempts to obtain heavy earthmoving equipment always met with competition from high priority projects such as airfield and road construction. Control work other than hand larviciding was delayed for many months after occupation on all of the bases occupied during the first 1 1/2 years of the campaign. Larviciding was not started on Efate and Guadalcanal until a malaria epidemic was well underway.

DDT, with its immense laborsaving potentialities, did not become available for general use until after the middle of 1944, by which time the major task of malaria control--that on Guadalcanal--had already been accomplished. The urgency of the situation in late 1942 and early 1943 made it necessary to undertake the work with all possible speed. A studied and strictly scientific approach was not possible. Although primary emphasis was placed on malaria control from the outset, it was not known how many vectors of this disease were present, or what other mosquitoborne diseases might be encountered. It was felt that quick control of mosquitoes in general would ultimately be the cheapest control of malaria and other epidemic diseases transmitted by mosquitoes.


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Antilarval activities

Larviciding .- The initial approach to mosquito control was largely through elimination of the immature stages of development. In part, at. least. this decision was dictated by the limited materials at hand, mostly diesel oil and a small number of hand-operated sprayers. Only limited drainage could be accomplished with the few troops assigned to malaria control activities, and line and service organizations were slow to cooperate in reducing the extensive water surfaces unless compelled to do so for personal comfort. Many months were to pass before an adequate number of vehicles and power sprayers was available, and airplanes were not used until after DDT became available late in 1944.

Of the several makes of hand-operated sprayers that were ultimately used, the 3-gallon chemical warfare sprayer, M1, was generally the most satisfactory. When modified with a suitable nozzle and oil-resistant hose and gasket, it made a fairly light and serviceable item. It had the added advantage of having interchangeable parts, a feature that did not apply to some other types of sprayers furnished as equipment to Army malaria control units. Until power sprayers became available, most larviciding was done with this item, carried by men on foot. In order to improve the efficiency of the operation, it was the general practice to distribute drums of oil to the field by truck, spotting them at strategic places so that walking could be cut to a minimum.

Once power sprayers became available, they were mounted on jeeps or weapons carriers and used to patrol the miles of water-filled roadside ditches and ruts that existed on nearly every base. Complete coverage of all static water surfaces was attempted each week on most bases, although this frequently could not be accomplished until the program was well underway. Eventually, it became the general practice for organizations to larvicide within their own cantonment areas, while the base malaria control organization assumed responsibility for all other larvicidal work. Larviciding crews were usually assigned definite areas of responsibility and were expected to become familiar with all details of the area that required attention. Crews usually contained 5 to 15 men each, depending upon the extent of the area to be covered. A noncommissioned officer was in charge of each crew. The members of the crew might work singly, in pairs, or as a group, again depending upon the problem at hand. Under conditions of normal rainfall, the crew was expected to be able to cover its assigned territory once in 4 or 5 days. This schedule left a safety factor of 2 or 3 days for repair of equipment, rainy days, and recreation.

Larviciding was not customarily carried out during periods of excessive rainfall because of the quick runoff of water and larvicide. On some bases, it was found expedient to organize "shock" oiling crews, usually of two or three men, whose duty it was to cover breeding areas missed by the regular crews. When unoiled breeding areas containing either fourth stage larvae or pupae of Anopheles were reported, it was customary for the shock crew to cover the


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area on the same day, regardless of the time of day at which the report was received. To expedite this work, survey crews resorted to the use of "flag" in the field to mark the breeding site, or, if necessary, a survey man would accompany the oiling crew into the field to point out the site. Although this system occasionally caused some hardship through disruption of planned after-hour activities, it served to emphasize the importance of thorough coverage. The comments of the shock crew called upon to take care of such special assignments were usually sufficient to improve the work of the regular crew.

The routine use of DDT, when it became available, resulted in a great economy of both labor and diesel oil. Usually, the spray schedule was not altered. Some larvicidal crews were equipped with 2-quart continuous-spray dispensers, and it was found that where scattered small pools were involved this item of equipment would hold enough solution to last a man for one-half day of work. Crews that continued to use knapsack-type sprayers adjusted the nozzles to the finest spray and could work all day without refilling. Spray crews were taught to apply only a minimal amount of the solution and to take advantage of wind drift in applying the larvicide to extensive water surfaces.

Dusting for the control of mosquito larvae was little practiced in the South Pacific Area. Before the use of DDT, some attempts were made to use paris green for the control of Anopheles, with varying success. This arsenical was used as a temporary control measure along grassy stream margins and around the edges of swamps until cleaning could be accomplished. Condemned flour was the most commonly used diluent but was unsatisfactory because in the humid climate bacteria and mold contamination tended to make it lumpy. Lime, pyrophyelite, and talc were not available for use as diluents. DDT dust, 10 percent, gave excellent control but was little used because of lack of suitable dusting equipment. Survey men often carried a 2-ounce can of DDT dust for treatment of rain barrels and small road-rut areas.

Airplanes were first used in the South Pacific for the dispersal of insecticides in May 1944. This type of work was initiated on an experimental basis by members of NAMRU (Naval Medical Research Unit) No. 2 with the cooperation of base malaria control personnel. The Husman-Longcoy spray apparatus was installed on a Piper Cub plane. It was first used for evaluating the effectiveness of aerial spraying in heavy jungle areas of the tropics, the equipment having already been thoroughly tested for performance at the laboratory of the U.S. Department of Agriculture, Orlando, Fla. The success of the first tests, and the increasing availability of DDT, made it apparent that this method of application of insecticides would greatly increase the efficiency of the entire program and would, in addition, obviate the necessity of many extensive drainage projects then under consideration.18 It offered, for the first time, a practical method of controlling mosquitoes in areas that

18 Report, Capt. Bruce E. Sasse, SnC, to Officer in charge, Malaria and Epidemic Control, South Pacific Area, 19 June 1944, subject: Airplane spraying.


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could not be entered because of the presence of uncharted landmines or other explosives. Steps were immediately taken to utilize aerial dispersal of DDT solutions and to explore the practicability of other types of airplanes for this work.

Several types of equipment for use on airplanes were developed in the South Pacific Area, 19 some of which were thought to be superior to the Husman-Longcoy spray apparatus because they could be readily constructed from material available at most airbases. Exhaustive tests, involving swath width, optimum flight speeds, droplet size, and biologic evaluations were conducted with various airplanes and items of spray equipment. No large multiengine airplanes were used routinely in the South Pacific since the terrain and the problems existing at that time were thought not to justify use of large aircraft. Aircraft used on both a routine and experimental basis included 65- and 85-hp. Piper Cubs and TBF and TBM planes. Tests were also conducted with F-AU airplanes, but the limited carrying capacity and high speed of this plane made it impractical for use in rear areas.

In order to increase the efficiency of aerial spray operations, and to take full advantage of the short period during the day when atmospheric conditions were suitable for spraying, a special ground crew was developed to load and service aircraft. This unit consisted of two or three men with a. 3/4-ton truck and tank trailer. Accessory equipment included such items as a motor-driven fuel pump, a hand-operated fuel pump, water-stop filter, fire extinguishers, sundry tools and replacement parts, DDT solution, and gasoline for the airplane. Thus equipped, the unit could move to the airfield nearest the site of operations for the day and service two Cub-type planes for one-half day of operations.

The effectiveness of aerial dispersal of larvicides in the control of mosquitoes exceeded the fondest hopes of the personnel in the South Pacific Area. Even in areas covered by a dense jungle, the fine spray penetrated to small ground pools, and the results were conclusive. In retrospect, it appears that the use of DDT and airplanes could have prevented the disastrous epidemics of malaria that delayed and threatened the success of the early phases of the South Pacific campaign.

During the latter part of 1944, the increasing use of DDT solution in diesel oil for both aerial and ground dispersal brought out a new operational problem. Hand mixing of this material was slow and tedious, and when the consumption on larger bases rose to several hundred gallons daily it was necessary to devise some means of mechanical mixing. The most practical of the methods devised for turning out large quantities of solution involved conversion of a 400-gallon capacity orchard sprayer to a mixing vat. A satisfactory

19 (1) Report, Lt. S. R. Fallander, USNR, February 1945, subject: Analysis of Aircraft Spraying and Equipment for Routine Use in Malaria Control. (2) Report, Lt. Comdr. H. S. Hurlbut, USNR, Guadalcanal, dated 10 and 12 Feb. 1945, subject: Droplet size, Distribution and Swath Width for Husman-Longcoy and Fallender Type Airplane Spray Equipment.


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solution could be obtained in a short time by means of mechanical agitation, and this means was used to supply DDT mixtures to all base control units and sanitary companies on Guadalcanal. The solution was returned to the empty diesel oil drums, which were used to transport the material from the central mixing station to substations. By continued re-use of the same drums, any residues of precipitated or undissolved DDT were not wasted but were retained in subsequent lots of the solution. An improved method for the preparation of DDT-diesel oil solution on a large scale was subsequently developed and is described in the section on Okinawa.

Filling. - If DDT had been available from the beginning of malaria control activities in the South Pacific, it is possible that much less work aimed at reducing the existing water surfaces would have been required. However, although diesel oil was an effective insecticide when properly distributed, its spreading qualities on water were not sufficient to give good control in pools and swamps containing abundant vegetation or debris. Under such circumstances, it became imperative to bring the total water surfaces requiring larvicidal treatment within the capacity of the crews available. Accordingly, a systematic attempt was made to eliminate all possible surface water. Among the first of the projects of this type was the filling of shell and bomb craters, abandoned bomb shelters, pits along roads, and foxholes. When bulldozers were available, they were used for the larger water catchments. Smaller catchments, such as foxholes, usually in somewhat inaccessible places, were best sought out and filled by crews of Melanesians. Since Melanesians customarily wore no footwear, one important modification had to be made in equipment to assure its proper use. Shovels were provided with a broad plate on the blade next to the handle so that foot pressure could be applied.

One of the most important of all filling operations was the elimination of road ruts by the use of a disk harrow. Especially on Guadalcanal, where innumerable miles of ruts were cut through the extensive grasslands, this was a most important contribution to malaria control. Once disked and closed to vehicular traffic, these are as were quickly revegetated and gave no further trouble.

Clearing and stream cleaning. - The clearing of undergrowth during the process of establishing bivouac areas automatically reduced the existing mosquito population to a considerable extent through the elimination of harborage. Although this was an important contribution to mosquito control, it was not considered sufficiently important to warrant clearing outside the cantonment area. The major portion of the clearing that was done for mosquito control consisted of cutting away the marginal growth along streams to expedite the passage of oiling crews and of removing emergent aquatic vegetation and debris from swamps and slow streams. Cleaning of streams hastened the runoff of water and greatly improved the drainage of an area. Since slow, sluggish streams and swamps were important sources of anopheline breeding during periods of little rainfall, reduction of the mosquito population in


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such places delayed the spread of breeding to temporary surface pools that developed following heavy rains.

The job of stream cleaning and clearing of underbrush was accomplished by native laborers whenever they were available. Troops were very reluctant to do this type of work because it was dirty, tiresome, and frequently resulted in fungus infection of the skin. Moreover, Melanesians were infinitely more skilled in the use of machetes, the preferred tool for this type of work, and could accomplish a great deal more than a similar number of troops working under the same conditions; moreover, the cost was relatively low.

Stream cleaning in the Solomon Islands was not entirely a dull routine. Many of the sluggish streams were inhabited by crocodiles, some of which reached a length of 10 or 12 feet. When one of these ill-tempered reptiles was encountered by a native crew, a scene of wild confusion ensued, which might be compared with the spectacle of a pack of dogs around a raccoon at bay. The Melanesians were anxious to kill or capture the quarry but were still respectful of the damage that could be inflicted by it. The chase nearly always ended in a feast of crocodile meat. The tail was much prized as food, the meat being white and shrimplike in taste when properly prepared.

Drainage. - Drainage projects planned and carried out by the malaria control organization in the South Pacific were customarily accomplished either by hand ditching, dragline ditching, or the use of explosives. By July 1944, on all bases combined, there were 157 miles of dragline ditches, 153 miles of hand-dug ditches, and 26 miles of ditches made with explosives. These figures involve only operations done primarily for the purpose of mosquito control. They do not include ditching accomplished by organizations engaged in establishing or improving bivouac areas, ditching in connection with new road construction, or shallow ditches cut with a pull grader.

Draglines, either 3/8 or 3/4-yard capacity, were used primarily on major drainage projects such as draining swamps, channeling sluggish streams, deepening existing roadside ditches, or connecting oxbows with stream channels. In swampy areas, the use of mats was necessary, especially during the rainy season. Ditching machines were of little value and were little used. When such equipment was used, it was necessary to follow up with a hand crew to cut the ditch sides back to a 45-degree angle to prevent cave-ins and ditch blockage. Underground title or tile inverts were not used.

Many of the roads constructed during the early phases of the campaign were completely unsatisfactory from a drainage standpoint. This was also true of some airfields, although Koli Field and Koli bomber strip, constructed in the flat alluvial plain on Guadalcanal, were notable exceptions. The most common fault in road construction was failure to cut ditches to grade and failure to install sufficient or properly placed culverts and connecting drainage with stream courses. For example, the main highway on Guadalcanal, between the little Tenaru and Nalimbiu Rivers, was so constructed that during the rainy season of 1943-44 it blocked the drainage of approximately 500


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acres of grassland to the south which was flooded with water to a depth of several inches. In order to eliminate this hazard, it was necessary to cut several miles of shallow ditches with a pull grader and to connect the entire network of ditches into a main ditch leading to the Nalimbiu River.

Hand ditching was customarily limited to the construction of shallow ditches. Most medical sanitary companies had ditching platoons organized to carry out such projects. Melanesians were not skilled at ditch digging and were little used for this purpose. Feeder ditches from bivouac areas were ordinarily dug by details from the organization concerned.

In very swampy areas, explosives proved the most practical method of ditching. Some work was accomplished with dynamite, but this item was difficult to obtain and, being inferior to bangalore torpedoes for use in swamps, was not widely used. Bangalore torpedoes, metal pipes packed with high explosive, condemned for combat use and hence readily available to malaria control organizations on some bases, proved ideal for use in soft, mucky soil. By laying these bangalores in a series and pressing them slightly into muck or soft mud, several yards of ditch could be dug with one explosion. Bangalores had the added advantage in that upon fragmentation the hundreds of pieces of sharp steel cut away the undergrowth and small roots, leaving a well-trimmed ditch. If greater depth was desired, a second series of bangalores, laid in the first ditch, would complete the job. In the same way, small shallow streams could be rapidly cleared of muck and debris.

On those islands having a thin topsoil and coral substratum, vertical drainage could be accomplished with relatively little effort. On Green Island, for example, vertical drainage of small catchments required only a few holes punched through the soil into the porous coral beneath. A single blow with an iron rod would often sink the rod to a depth of several feet. Limestone sinkholes were present on some of the islands, and although they often silted in and became closed they could usually be opened with a single charge of dynamite. On Munda, Ondongo, and Bougainville, large bomb craters in some instances gave excellent vertical drainage.

Flushing. - Flushing dams were constructed in suitable streams in a few instances, and where accompanied by stream cleaning they were very effective in controlling mosquito breeding of all kinds. Without stream cleaning, they were ineffective. In all, a total of nine damns were constructed, seven on Guadalcanal and two on Efate. In view of the difficulty of construction, and lack of suitable materials, it is doubtful if wide use of flushing dams under most conditions of military occupation is justified.

Natural control . - Gambusia, the surface feeding fish often used in tropical areas for the control of anopheline mosquitoes, was used on several bases in the South Pacific. Stocks were placed in swamps and permanent ponds on Espíritu Santo and Munda, and in wells and cisterns of Efate. They had been stocked on the Russell Islands many years previously. Their chief value was in reducing breeding in marginal areas not readily accessible for larviciding.


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They were of little or no value in the presence of vegetation. Except for use in wells and cisterns, they were not routinely stocked within the established control areas. Even after establishment, constant maintenance and restocking was necessary.

Flumes. - Coastal lagoons on Bougainville, Green, Emirau, and Guadalcanal Islands constituted one of the most difficult control problems encountered. There were more than 60 lagoons along the coast within the occupied area on Guadalcanal. These served as permanent breeding foci for A. farauti during the dry season, and even though breeding in other areas was minimal at that time the populations developing in the lagoons served to repopulate adjacent areas whenever surface water became available. Control of breeding in lagoons was therefore given high priority in the control program.

These coastal lagoons ordinarily remained closed for long periods of time, although they were occasionally opened by flash floods during periods of heavy rainfall. Water within the lagoons rose to a level of 3 or 4 feet above sea level and provided ideal breeding sites for malaria mosquitoes. Cutting ditches through the enclosing sandbar offered only a temporary solution since wave action would quickly close the mouth of the stream, usually within 24 hours. The problem was finally solved by the use of flumes made from a series of oil drums with the ends removed and welded together end to end. The lagoon end of the flume was set approximately 6 inches below sea level at mean low tide, and the flume extended out through the sandbar until the opposite end was approximately 12 inches above the floor of the sea beyond the area of normal surf action. The length of the flume depended upon the pitch of the beach. The first flumes installed were placed at the narrowest point in the sandbar, but experience showed that there was more likelihood of the structure being washed out during storms if placed at this point. Subsequently, it was the general practice to place flumes well to one side of the narrow point in the sandbar.

Flumes were held in place by pilings placed on each side at intervals of 5 feet. These pilings were set with the aid of a water jet from a 500-gallon-per-minute fire pump. An experienced crew of 14 men with dragline, bulldozer, and fire pump could set double flumes some 200 feet long in from 4 to 6 days. Flumes were prepared in sections of from 15 to 20 feet in length at a welding shop and transported to the job in sections. Multiple flumes were required in some instances for large lagoons, six being the maximum installed at any one lagoon. When multiple flumes were set, they were usually laid in pairs, each pair being somewhat removed from the adjacent pair.

Flumes properly installed not only permitted the water in the lagoon to be drained, but permitted entry of some sea water and at least a slight change in the salt content of the water in the lower end of the lagoon. There was also daily fluctuation of water level in the lagoon. Under these conditions, the flora of these coastal swamps either disappeared, or was considerably altered. Once flumes were installed, there was usually little necessity for other control measures.


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Agriculture . - Cultivation of extensive areas of former grassland on Guadalcanal proved to be an effective mosquito control measure. Eventually, some 2,500 acres between the little Tenaru and Nalimbiu Rivers were under cultivation for the purpose of supplying troops with fresh vegetables. Much of this grassland area had at one time been badly rutted by vehicular traffic, and although this situation was largely corrected by the time the farm was established the cultivation of the area assured freedom from mosquito breeding. Even during periods of heavy rainfall, the surface water in the cultivated areas did not persist long enough to permit breeding.

Antiadult activities

Space spraying . - During the early phases of the South Pacific campaign, the only space sprays available were the petroleum base sprays dispensed with old-fashioned "flit guns." These were more often used against flies than mosquitoes. They were relatively effective in screened messhalls and similar places but were totally ineffective in open quarters. Pyrethrum Aerosol dispensers, the well-known "mosquito bombs," became available in limited supply in forward areas, during the first half of 1943, and were first used during a combat operation in July 1943 in the New Georgia campaign. By the time of the landing on Bougainville in November 1943, an adequate supply of Aerosol bombs was available and they were widely used. As new supplies arrived, there was a gradual replacement of pyrethrum Aerosols with bombs containing a small percentage of DDT. Five-pound refillable dispensers were used to some extent in messhalls, recreation areas, theaters, and similar places where large amounts of spray were needed.

Aerosols were little used in combat areas but were extremely valuable in rear areas. Proper use of an Aerosol bomb in shelters occupied during night air raids would give protection to a number of men, and their use in this manner was encouraged. In unscreened quarters and open foxholes, the effect was extremely transitory, especially during periods of even slight air movement. For killing mosquitoes in screened quarters or in mosquito bed nets, Aerosol bombs were unexcelled. Aerosol preparations were also widely used to spray huts occupied by native laborers, in order to kill any malaria infected mosquitoes that lingered following a nocturnal blood meal. A daily schedule was established for this work, with a native dresser trained to do the spraying.

Thermal Aerosols were used on a few bases in the South Pacific, largely on an experimental basis.20 Although they were of value under certain circumstances in reducing existing adult mosquito populations, their general use was not possible because of limited road nets. Nighttime operation was most effective, since the atmospheric conditions prevailing at that time usually held the Aerosol fog close to the ground. Daytime applications along the beach

20 Brescia, F.. and Wilson, I. B. Treatment of Native Villages with the Aerosol Generator. J. Econ. Ent. 40: 313-316, 1947.


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area, for reduction of sand fly populations, were successful in some instances but the effect could seldom be noted for more than 2 or 3 days.

Residual spray applications of 5-percent DDT in kerosene were by far the most effective insecticide applications for reduction of adult mosquito populations in the South Pacific. Eventually, nearly all buildings and enclosed tents were so treated. Most of the work was done with a power-driven paint sprayer operating at low pressure; the solution was applied to screens with a paintbrush. Other types of spray equipment were also used for treatment of the interior of structures. Regardless of the equipment used, the recommended rate of application was 1 quart per 250 square feet of surface. The general "rule of thumb" was to spray wooden surfaces until wet, but just short of runoff. This treatment was not only effective against mosquitoes and flies but was remarkably effective in eliminating ants from quarters where they had been extremely annoying before the use of DDT.

DDT residual-type spray was also used to impregnate bed nets. This practice was begun during the latter part of 1944, and the methods developed at that time were later used for treating bed nets and jungle hammocks for the use of two divisions. The solution was applied with either a power-driven paint sprayer or the standard chemical warfare decontamination sprayer such as was widely used for larviciding. Application was at the rate of 1 gallon per 6 to 8 nets. The method of application was to arrange the nets in a pile, spray the top net, turn it to start a new pile, and then spray the opposite side. Operating in this fashion, 6 men with 4 hand-operated sprayers were able to spray from 60 to 100 nets per hour a similar crew working with power-operated sprayers could treat twice as many in the same period of time. This included preparation of the nets, spraying, and hanging the nets to dry.

Nets tested immediately after treatment and after being stored for 1 month were lethal to A. farauti and other species of insects used for biologic tests of the material. No further information as to the duration of effectiveness was obtained.

Screening . - Screening of any kind was practically nonexistent during the early phases of the campaign, but by early 1944, it was available in adequate amounts in all except forward and combat areas. Table 67 shows the relationship between length of occupation of each base and the percentage of screened quarters as of June 1944. Cloth bobbinet was preferred to wire for field use and for use on installations near the shore where it was exposed to windblown salt spray. During the time that the amount of screening was limited, the following priorities were established: Hospitals, kitchens, and messhalls; showers, particularly for organizations with men on night details; latrines; and offices, tents, and all other living quarters. Judicious use of the available screening materials undoubtedly contributed greatly to the reduction of malaria, as well as to the general comfort.

Bed nets were probably the most valuable single mechanical barrier against mosquitoborne diseases. There were instances on Guadalcanal and elsewhere


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TABLE 67. - Estimated percent of quarters screened,1 South Pacific Area, June 1944

during the height of malaria epidemics where less than a week of bivouacking without bed nets resulted in a high infection rate among the troops concerned. A single night of exposure often resulted in considerable malaria in an organization. Because of such costly experiences, orders were issued making it the responsibility of each officer and man that bed nets should be available on the first night ashore except among troops actually in combat. Jungle hammocks were issued to many troops, including entire divisions beginning late in 1943. Where proper use of this item was possible, it gave excellent protection. However, the issue of jungle hammocks to all personnel of a combat force was probably not justified because these relatively bulky pieces of equipment were among the first to be discarded during combat operations. Further, it was seldom possible for all the men of a division to find suitable places for suspension of the hammocks. Head nets were practically never used for protection from mosquitoes, and their routine issue in the South Pacific Area was not considered justified.

Repellents . - Repellents were potentially one of the more valuable means of personal protection from mosquitoes and mosquitoborne diseases but were relatively little used for their intended purpose. They were more often used for protection from pest mosquitoes rather than Anopheles, and it is doubtful if repellents contributed materially to the prevention of malaria. Dimethyl phthalate, the most effective repellent for Anopheles in the southeastern United States, was comparatively ineffective against A. farauti. It was effective against chiggers and was used for that purpose on Bougainville where scrub typhus threatened to become a serious military disease. Rutgers 612 was superior to dimethyl phthalate for protection from A. farauti. The standardized repellent, consisting of 6 parts dimethyl phthalate, 2 parts Rutgers 612, and 2 parts Indalone, was not available until 1945.


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In spite of the ineffectiveness of the repellents against A. farauti, their failure as a means of preventing malaria must be attributed more to antipathy toward their use than the fault of the item itself. Combat personnel often claimed that the enemy could smell the repellent if the wind was in the right direction. Service troops objected to the general messiness of the solutions and to the fact that dimethyl phthalate is a solvent for plastics. On Guadalcanal, nurses quartered in a beach area where sand flies were annoying refused to use repellents for protection but at the same time used copious quantities of an equally messy suntan oil. Supplies of repellent were adequate after the middle of 1943, and a surplus of over 12 million bottles by the end of 1944 attested to the failure to use this item.

Suppressive Medication

Administration policy and procedure

Atabrine was the only drug used in large quantities for the suppression of malaria in the South Pacific Area. Its value was established slowly and with difficulty. At the beginning of the campaign, little was known about its absorption, blood concentration, excretion, or toxicity. Throughout 1942 and 1943, there was disagreement and uncertainty regarding its use and dosage. Standard treatises upon malaria warned that Atabrine had a small margin of safety and that individuals receiving the drug should be under close observation.

Administration of the drug was frequently begun on shipboard as troops approached malarious islands, and seasickness, diarrhea, and emotional states were sometimes attributed to this drug. The yellow discoloration which it gave to the skin, although harmless, gave rise to the suspicion that Atabrine was injurious to the liver, and this rumor was intensified when epidemics of jaundice occurred among troops taking the drug. The rumor that Atabrine caused sterility was common and was fostered by the enemy through the broadcasts of "Tokyo Rose." The fact that this was effectively disproved by men of units sent for rehabilitation to populated areas did little to improve Atabrine discipline in forward areas. Added distrust of the drug arose when troops who supposedly were taking the recommended suppressive dose developed malaria. There was wide divergence of opinion among the medical officers of the Marines, who assaulted Guadalcanal in August 1942, regarding the value and the dangers of Atabrine as a suppressive drug. Some units took quinine, others took Atabrine, and many took nothing. There was no method such as was subsequently developed to supervise the administration of suppressive therapy.

The directives from the theater surgeons office on the subject of suppressive Atabrine therapy illustrate the growth in knowledge of and confidence in this drug as the campaign progressed. The first such directive appeared in August 1942 and is quoted in part as follows:


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Malaria Prophylaxis

It is recommended that malaria prophylaxis be given as follows: Atabrine is the drug of choice. It should he given in doses of 0.2 grams twice weekly (0.4 grams per week). When it is used, It is to be considered advisable, after 3 months, because of slight cumulative effect of the drug, to substitute quinine for a period of 1 month. Quinine is given prophylactically in doses of 15 grains daily. This should be continued for one month and then Atabrine *   *   *  resumed.

In October 1943, a new directive maintained the suppressive dose of Atabrine at 0.4 gm. per week, but the schedule was changed so that the drug was taken in one-half tablet (0.05 gm.) amounts per day on each day of the week except Sunday, when one tablet (0.1 gm.) was taken. In January 1944, the weekly suppressive dose was increased to 0.6 gm. per week, given in amounts of 0.1 gm. each day except Sunday. In November 1944, the final theater directive 21 on this subject increased suppressive doses of Atabrine to 0.7 gm. per week, 0.1 gm. to be taken daily.

Results

The value of Atabrine as a suppressive drug was gradually established by clinical observations made within the theater at a time when the studies on absorption, blood levels, and excretion were not yet available. It became apparent that a few heavily seeded units which had good Atabrine discipline were suppressing a large share of their malaria as long as they continued to take the drug. Thus, the 6th Marines reported less than 250 cases of malaria while on suppressive medication during January and February 1943 on Guadalcanal, as compared with over 2,500 cases in May and June after they had moved to New Zealand and had discontinued the drug. This organization of approximately 4,500 men was on Guadalcanal during the height of the malaria epidemic, was in severe combat, and had fewer cases of malaria than any other organization of equivalent size exposed in this area at the same time. Every man in this organization was given Atabrine under supervision and with the use of a checklist roster. Loading doses of the drug were given before arrival on Guadalcanal and 0.6 gm. per week while there. This dosage was given at a time when the theater directive called for 0.4 gm. per week. The regimental surgeon reported no evidence of toxicity due to the drug.

The 147th Infantry Regiment took suppressive medication in dosage of 0.4 gm. with poor to fair supervision from December 1942 through April 1943 on Guadalcanal and had a malaria rate during these 5 months which ranged around 1,000 per 1,000 per annum. This rate promptly rose after discontinuation of Atabrine in nonmalarious Samoa to an average of over 3,000 per 1,000 per annum for 5 mouths with peaks as high as 14,000 per 1,000 per annum in selected groups. Atabrine was then resumed with excellent supervision, and the rate dropped abruptly to well under 100 per 1,000 per annum.

21 Memorandum 183, Headquarters, South Pacific Base Command, 1 Nov. 1944, subject: Suppressive Treatment of Malaria.


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Toxicity. - Temporary and minor gastrointestinal symptoms were not uncommon when Atabrine was first taken. Information regarding this possibility was publicized in directives and in educational material. It was recommended that medication for such individuals be continued in lower dosages for a brief period and that the full dosage be resumed as soon as possible. Less than 1 person in 1,000 developed toxic symptoms from the prescribed dosages. A few cases of skin lesions which simulated lichen planus pigmentation of the palate and subungual tissues 22 in those who took suppressive Atabrine for long periods was noted. Severe toxic manifestations including exfoliative dermatitis, hepatitis, and nervous symptoms such as confusion states were quite rare among those who took only the prescribed dose of 0.7 gm. weekly.

Research, education, and discipline

The careful studies and blood Atabrine determinations of Schaffer and Lewis 23 showed that the development of clinical malaria in troops who were supposedly taking Atabrine in suppressive doses was associated almost invariably with extremely low blood levels. These workers came to the opinion that a low Atabrine blood level was almost always due to laxity in taking the prescribed medication. They were able to confirm this by careful supervision of Atabrine administration with resultant rise in serum concentration and concurrent decrease in malaria relapse rate. Most important of all, they developed a technique which was capable of convincing the most skeptical line officer of the fact that a tightening up of Atabrine discipline would quickly reduce the malaria rates among his men.

Administration of Atabrine for suppressive purposes was ordered to be by roster for both officers and men. An officer or a noncommissioned officer was detailed to watch the actual swallowing of the drug by each individual. Precautions were taken to see that individuals who were not present were required to report and to take their medication under supervision. As already noted, the final directive on suppressive medication ordered a dosage of 0.7 gm. weekly given as 0.1 gm, daily. An alternative procedure was undertaken by the 25th Division during the latter part of 1944; the drug was given on 2 days a week in doses of 0.4 and 0.3 gm. The administrative problem was lessened and suppression appeared to be adequate.

Many men became adept in circumventing these directives by palming the drug or tucking the tablets between teeth and cheek. Administration by roster did eliminate much of this, but the only adequate solution was an educational program to impress each man with the value of the drug and with its harmlessness.

22 Lippard, V. W., and Kauer, G. L., Jr.: Pigmentation of the Palate and Subungual Tissues Associated With Suppressive Quinacrine Hydrochloride Therapy. Am. J. Trop. Med. 25: 469-471, November 1945.
23 Schaffer, A. J., and Lewis, R. A.: Atabrine Studies in the Field; I. The Relation of Serum Atabrine Level to Breakthrough of Previously Contracted Vivax Malaria. Bull. Johns Hopkins Hosp. 78: 265-281, May 1946.


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Discontinuance of Atabrine suppressive therapy

Atabrine suppressive therapy was discontinued in lightly seeded troops throughout the South Pacific Area as control measures became adequate to permit doing so without danger of significantly increasing malaria rates. This policy was initiated on Efate in September 1942 at a time when the malaria rate had fallen to 144 per 1,000 per annum from a peak of nearly 2,700 per 1,000 per annum during the previous April (table 61). Malaria rates in these heavily seeded troops rose rapidly during October and November, and suppression was resumed in all except a few uninfected organizations. This evidence against the blanket discontinuation of suppression in heavily seeded troops was strengthened during the next few months by such experiences as noted previously with the 6th Marines and the 147th Infantry.

These experiences resulted in the following prerequisites for the discontinuation of suppressive medication in malarious territory:

1. Anopheline breeding must be adequately controlled on the occupied portion of the island and also in any areas which the particular organization might enter for training or other activities.
    2. Troops must be unseeded or lightly seeded with malaria. This was determined by the history of previous exposure and by a study of the malaria rates of each organization. Those units with a history of a high malaria rate were rarely recommended for discontinuation of suppression even if their rates fell to low levels under suppressive therapy. Occasionally, medication would be discontinued in a small pilot group in order to determine the degree of seeding in a large organization.
    3. Troops were not removed from Atabrine suppression therapy while ground combat was in progress or was threatened or when they were scheduled for early movement to a combat or malarious area.

   The final theater directive on this subject is quoted in part:
    4. Island commanders are authorized to discontinue Atabrine suppressive treatment in selected "lightly seeded" units upon the recommendation of the Island malariologist as control measures become sufficiently advanced to permit doing so without interfering with the military effort.
    5. Suppressive treatment may conceal the actual amount of infection or the gradual seeding of a unit. Apparent freedom from malaria may lead to a false sense of security and carelessness in regard to truly preventive measures such as mosquito control and individual protective measures. Therefore, the eradication of the Anopheles mosquito and protective measures against it must be continued with unabated energy.

The medical officer of an organization in which Atabrine was discontinued was advised to make an exception of those men known to have had vivax malaria and to continue them on suppressive medication.

Field Research

It is difficult to make any clear distinction between the routine daily operations and the investigational work that was necessary to initiate a malaria


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control program in the South Pacific. Before occupation of the various malarious bases, there was little concrete information about the problems to be encountered. From the beginning of the work, and almost throughout the period of occupation, there was need for continuing investigation of problems that had a direct bearing on the control program. These were usually done piecemeal, either in conjunction with or as adjuncts to the operational routine that became established. Occasionally, late in the South Pacific campaign, it was possible to assign personnel or units to investigational work for brief periods of time. On numerous occasions, from early 1944 on, it was possible to engage in research work in cooperation with special teams sent out by NAMRU No.2.

Before occupation by the Armed Forces, only 30 species of mosquitoes were known from the entire Solomon Islands; by the end of the war, 70 species of this group were known from Guadalcanal alone. Practically all detailed information about the mosquito fauna of the South Pacific islands was either acquired or confirmed by entomologists working on insect-borne diseases during World War II. Initially, it was necessary to determine what vector or vectors of malaria were present on each base. The fact that A. farauti proved to be the only important species from this standpoint did not lessen the investigational work necessary to establish this fact. The bionomics of A. farauti were studied in detail. 24 Similar critical studies were made with other species to clarify their role in the transmission of filariasis.25 Other field investigations in entomology were concerned with the hosts of trombiculid mites, the incidence and species involved in human myiasis, and the distribution and biologic features of various species of flies.

In the field of control operations, investigations were concerned with the determination of flight requirements of airplanes for use in aerial distribution of insecticides, droplet size analysis of airplane dispensed DDT, suitability of various types of hand sprayers, minimum lethal dosages of insecticides under tropical conditions, methods of applying residual type DDT spray to tentage and mosquito bed nets, and use of DDT in area treatment against adult mosquitoes. 26 The work accomplished was almost invariably the contribution of a number of individuals working together for the benefit of the program as a whole.

Parasitologic field research activities consisted almost entirely of surveys of malaria and filariasis in natives and troops. The results of the malaria surveys have been given previously.

24 Daggy, R. H.: The Biology and Seasonal Cycle of Anopheles farauti on Espíritu Santo, New Hebrides. Ann. Ent. Soc. Amer. 38: 1-13, 1943.
25 (1) Byrd, E. B., and St. Amant, L. S.: Studies on Filariasis. Newsletters No. 14 and No. 16, August and October 1944, Headquarters, Malaria and Epidemic Control, South Pacific Area. (2) Rieber, R. J.: Studies on Filariasis Transmitted by Anopheles koliensis Owen in a Native Labor Camp on Guadalcanal. Newsletter No. 26, July 1945, Headquarters, Malaria and Epidemic Control, South Pacific Area.
26 Special Report, Lt. John D. Maple, USNR, and Maj. Paul W. Oman, MC, dated 27 Nov. 1944, subject: Use of DDT in Area Treatment Against Adult Mosquitoes.


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OTHER ACTIVITIES OF THE ANTIMALARIA ORGANIZATION

The Malaria and Insect Control Organization eventually engaged in a wide series of activities which grew out of the technical abilities of its personnel, especially those of the parasitologists, engineers, and entomologists. Most of these additional activities were concerned with the control of arthropodborne diseases, although there were occasional ramifications such as the campaign to exterminate rats, not only to destroy rats as hosts of the mite of scrub typhus but also because of the rats economic depredations. The activities to be described briefly were usually carried on concurrently with malaria control work. Malaria was a year-round problem on the malarious islands of the South Pacific.

Dengue fever reached epidemic proportions on the Fiji Islands, New Caledonia, Efate, Espíritu Santo, and Tulagi-Florida Islands, in 1942-43. On Espíritu Santo alone, it caused illness in over 25 percent of the military population and resulted in over 80,000 sick days between January and June 1943.27 Malaria tended to obscure the importance of this disease; actually, dengue occurred in sharper outbreaks and with a greater temporary disability to a military force than any other arthropodborne disease. Although the seriousness of malaria transmission was usually obscured by the use of suppressive medication, there was no such drug to blunt the immediate effect of a severe outbreak of dengue. Local malaria control groups had given repeated warnings of the potential hazard of tin can dumps and of other breeding places of the dengue-transmitting mosquito, Aedes aegypti. With the outbreak of these epidemics, the malaria control organization was given adequate authority, personnel, and equipment to cope with the problem. As a result, there was no dengue outbreak in 1944 on any base except in New Caledonia where it was held to very small proportions.

A severe outbreak of filariasis in the Samoan defense area led to the medical evacuation of many thousands of troops engaged in garrison and training activities. Studies made during this epidemic demonstrated that the disease syndrome called "mumu" by the natives was an early manifestation of infection by W. bancrofti. This syndrome was characterized by localized swellings, retrograde lymphangitis, lymphadenitis, and genital manifestations. 28

27 Stewart, F. H.: Dengue Analysis of the clinical syndrome at a South Pacific Advance Base. U.S. Navy M. Bull. 42: 1233-1240, June 1944.
28 (1) Dickson, J. G., Huntington, R. W., Jr., and Eichold, S.: Filariasis in Defense Force, Samoan Group; Preliminary Report. U.S.. Navy M. Bull. 41: 1240-1251, September 1943. (2) Fogel, R. H., and Huntington, R. W. : Genital Manifestations of Early Filariasis. U.S. Navy M. Bull. 43: 263-270, August 1944. (3) Englehorn, T. D., and Wellman, W. E.: Filariasis in Soldiers on an Island in the South Pacific. Am. J. Med. Sc. 209: 141-152, February 1941. (4) Huntington, R. W., Jr., Fogel, R. H., Eichold, S., and Dickson, J. G.: Filariasis Among American Troops in a South Pacific Island Group. Yale J. Biol. & Med. 16: 529-537, May 1944. (3) Thompson, K. J., Rifkin, H., and Zarrow, M.: Early Filariasis in Young Soldiers; Clinical and Pathologic Analysis. J.A.M.A. 129: 1074-1079, December 1945. (6) Byrd, E. E., St. Amant, L. S., and Bromberg, L.: Studies on Filariasis in the Samoan Area. U.S. Navy M. Bull. 44: 1-20, January 1945.


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It was discovered that A. farauti. the chief vector of malaria in the Solomons and New Hebrides, was also the most important vector of filariasis in these islands. 29Anopheles koliensis was also found to be a vector of filariasis on Guadalcanal. Thus, the exercise of malaria control on these islands had fortunately furthered the control of filariasis.

The outbreak of tsutsugamushi disease (mite-borne typhus) on Bougainville in 1944 resulted in making the local malaria control organization responsible for preventive measures, including rodent control and the impregnation of clothing with dimethyl phthalate. Study of this disease and its control was aided by the arrival of an advance group from NAMRU No. 2. Over 75 cases of tsutsugamushi disease occurred on Bougainville, 49 of which were reported by Anderson and Wing.30

Rodent control m as undertaken both to prevent economic loss from rats and to prevent spread of epidemic diseases which were harbored or transmitted by rats or their ectoparasites. An officer qualified as a mammalogist or with civil experience in rodent extermination was appointed as rodent control officer and attached to the Malaria and Insect Control Group at each large base. An adequate number of enlisted men, equipment, and transportation were provided. A manual was prepared, men from each military unit on the island were trained in the technique of rodent extermination, and their work was then supervised. Fumigation of ships for rat extermination was done on request.