Contents

CHAPTER XIV

Statistics of Malaria

Fred H. Mowrey, M.D.

Malaria, one of the world's greatest causes of morbidity, has played a dominant role in many military campaigns, although not so devastatingly as the pestilential diseases of typhus, plague, the dysenteries, and smallpox.

HISTORICAL NOTE

Malaria played a vital part in Caesar's campaigns during the Roman civil wars. Malaria was the savior of Rome from the Germans on many occasions. Celli¹ writes: "The Queen of the World suffered much at the hands of these Barbarians, but, in her dethronement, she found ample revenge. For in the swamps around Rome there lurked swarms of mosquitoes eager for fresh healthy blood, and they it was that now attacked the foreign invaders. These Northern warriors, who were forced to spend the summer within or outside Rome, died, or lingered on for years weakened by daily fever, and this happened over and over again for centuries with a terrifying regularity. The various German troops made their departures more in the manner of a funeral procession than in a victor's triumph." Celli referring to Otto I in 964 writes, "The Emperor, however, celebrated the Nativity of St. John (June 24) and the Feast of the Holy Apostles (June 29) and turned homewards from the Roman Land. But he was overcome by a fate more unhappy than he could ever have looked for, for in his army there broke out so great and deadly a pestilence that almost all died, and those who still kept their health only dared to hope to live from one evening to the next morning." In 1167, Emperor Frederick I failed to conquer Rome. "Suddenly, such a deadly fever broke out in his Army that, within seven days, almost all the princes who fought with him against the Church were unexpectedly snatched away by a miserable death." He was forced to flee leaving uncounted dead.

Malaria was ever-present during the Siege of Mantua in 1796-97. Prinzing² states that malaria broke out with great severity and acquired virulent forms which played a decisive role in the result.

A typical example of the effect of malaria in military campaigns occurred among British and French troops in Macedonia in 1918. Some 80 percent of 120,000 French troops were hospitalized. Over 25,000 British troops were invalided home with chronic malaria, and more than 2 million

¹Celli, Angelo : The History of Malaria in the Roman Campagna. London: John Bale, Sons & Danielsson, Ltd., 1933.
²Prinzing, Friedrich: Epidemics Resulting From Wars. Oxford: At The Clarendon Press, 1916.

450

man-days were lost in the British Macedonian Army during 1918 because of malaria.³

Malaria also has been a problem to the U.S. Army. There are no available statistics on malaria prior to 1818, but we know it was prevalent before then. "As early as 1776 the Continental Congress ordered the Medical Committee to forward 300 pounds of Peruvian bark to the Southern Department for the use of troops."⁴

During the War Between the States, one-half of the white troops and four-fifths of the Negro troops in the Northern Armies contracted malaria annually. There were 10,063 deaths due to malaria. In addition, more than 1,000 Confederate troops died of malaria in Northern prisons. The incidence of malaria during the U.S. Civil War, in Northern troops, per 1,000 per annum, is shown in the following tabulation:⁵

¹No Negro troop strength.

During the Spanish-American War, there were 90,461 admissions for malaria during the calendar year 1898, with 349 deaths. The annual admission rate was 611.78 per 1,000. A rate of 1,924.78 per 1,000 per annum occurred in Cuba with a mortality rate of 14.02 per 1,000 per annum.⁶ Theodore Roosevelt stated that malaria was the chief enemy in Cuba. Every officer in his regiment, except himself, was down at one time or another with malarial fever. "Though the percentage actually on the sicklist never got above twenty, there were less than fifty percent who were fit for any kind of work."⁷

In the First World War, from 1 April 1917 to 31 December 1919, there were 15,555 admissions for malaria, 36 deaths, 28 discharges for disability, and 194,529 man-days lost. Most of the malaria occurred among troops engaged in training in facilities located in endemic malarious areas in the United States. Only 950 admissions for malaria occurred in Europe.⁸

³Wenyon, C. M., Anderson, A. G., McLay, K., Hele, T. S., and Waterston, J.: Malaria in Macedonia, 1915-1919. J. Roy. Army M. Corps 37: 81-108, August 1921.
⁴Blanton, W. B.: Medicine in Virginia in the Eighteenth Century. Richmond, Va.: W. Byrd Press, 1931.
⁵Medical and Surgical History of the War of the Rebellion. Medical History. Washington: Government Printing Office, 1888, pt. III, vol. I.
⁶Annual Report of The Surgeon General, U.S. Army. Washington: Government Printing Office, fiscal year, 1900.
⁷Major, Ralph H.: Fatal Partners: War and Disease. Garden City, N.Y.: Doubleday, Doran & Co., Inc., 1941, p. 195.
⁸The Medical Department of the United States Army in the World War. Washington: U.S. Government Printing Office, 1928, vol. IX, p. 512.

451

The incidence of malaria among U.S. troops was of little significance following World War I, occurring chiefly among troops stationed in Panama, Puerto Rico, and the Philippine Islands. The incidence for the entire Army during 1941 was 4.74 per 1,000 per annum.

WORLD WAR II

The disease became, however, a problem of serious importance during World War II, when U.S. Army troops campaigned in highly malarious areas in many parts of the world. Never before had the Medical Department been called upon to combat a problem of such magnitude. It is indeed a tribute to the preventive measures adopted that the menace of malaria did not more seriously interfere with military operations. However, these sanitary measures were not immediately available to combat troops in such areas as Guadalcanal, New Guinea, China, Burma, India, North Africa, Sicily, Italy, and elsewhere. Accordingly, malaria exacted its toll in morbidity and man-days lost.

Malaria assumed a dominant role in many Pacific areas-Green Island, Emirau, Bougainville, Vella Lavella, Suaba, Efate, Esp?ritu Santo, Guadalcanal, Tulagi-Florida, Russell Islands, Munda, and the Treasury Islands-seriously depleting combat effectiveness and increasing the workload of the Medical Department. This was best illustrated in Guadalcanal where there were 10,206 primary cases of malaria among U.S. Army troops during March-December 1943:⁹

¹Data are not available for primary cases occurring in January and February.

The 1st Marine Division ceased to be an effective combat unit for many months owing to the hospitalization for malaria of approximately 80 percent of the command.¹⁰ Four out of five units had to be removed from combat for rehabilitation. The Americal Division was transferred from New Cale-

⁹Essential Technical Medical Data, South Pacific Base Command, for March 1945. Inclosure 13-4, unnumbered table entitled "Primary Cases of Malaria, Army, Guadalcanal, 1942-44."
¹⁰Essential Technical Medical Data, Southwest Pacific Area, for January 1944.

452

donia to Guadalcanal during November and December 1942. Owing to the exigencies of combat and failure to appreciate the problem, few, if any, antimalarial measures were taken. The number of cases of malaria rapidly increased, weekly rates as high as 2,500 per 1,000 per annum being reported. The division had to be transferred to Fiji in March 1943 for rehabilitation. Mass therapy of the division was undertaken between April and June, when all medication was discontinued. The hospitalization rate promptly rose to 4,220 in August. It was still 2,948 in late October when suppressive therapy with Atabrine (quinacrine hydrochloride) was reinstituted, with a consequent drop to 80 by late December 1943.¹¹

The 25th Infantry Division engaged in combat on Guadalcanal in January 1943. This division also failed to take proper antimalarial measures. As a consequence, the malaria rate rose to 2,385 per 1,000 per annum during the last week of April. This division was transferred to New Zealand in December 1943 for rehabilitation, and thence to New Caledonia in February 1944 for reorganization. It is estimated that approximately 46 percent of the division had one or more attacks of malaria during 1943.

The 43d Infantry Division entered Guadalcanal in March 1943 and subsequently participated in the Russell Islands and New Georgia campaigns. This division required rehabilitation in New Zealand during February and March 1944. In order to determine the amount of seeding in the division, a small control group was taken off Atabrine. The malaria rate for this group rose to 2,000 per 1,000 per annum; whereas the rate for the remainder of the division, which continued on Atabrine suppression, did not exceed 236 per 1,000 per annum.

Malaria was a great problem in the Southwest Pacific Area, 47,663 attacks occurring during 1943 alone. Sixty-seven percent of the 32d Infantry Division had malaria during the 10-month period following their withdrawal from New Guinea. The effectiveness of malarial control was demonstrated in the Milne Bay area of New Guinea where the rate was 3,308 in January 1943. Following the institution of control measures, the rate dropped to 100 by May and to only 30.72 by January 1944.¹²

There were 9,160 cases of malaria in the China-Burma-India theater during 1943, with nearly 115,000 man-days lost. Of the first 2,400 patients admitted to the 20th General Hospital, located near Ledo in Assam, 73 percent had malaria. At one time, 55 percent of the beds were occupied by patients with malaria.¹³ The effect on troops of exposure to the endemic disease is illustrated by 92 men of the 900th Airborne Engineer Company who traveled from Ledo to Tagap. En route, 54 were hospitalized with malaria; out

¹¹Essential Technical Medical Data, South Pacific Area, for April 1944.
¹²Essential Technical Medical Data, Southwest Pacific Area, for May 1944.
¹³Essential Technical Medical Data, China-Burma-India Theater, for August 1943.

453

of the 38 who reached Tagap, 20 had malaria on arrival.¹⁴ An epidemic of malaria occurred at the 1306th Air Force Base Unit, Air Transport Command, located in Karachi, India, in 1944. There were no cases during August, but the rate rose rapidly to 1,202.3 per 1,000 per annum during the first 2 weeks of October. The rate dropped to 148 during the first 2 weeks of November following the institution of malaria control methods.¹⁵

Malaria was a serious problem to North African theater forces. It was prevalent in the areas of Rabat and Port Lyautey in Morocco, the Constantine area in Algeria, the Tunis-Bizerte-Ferryville area in Tunisia, Catania in Sicily, Corsica, Sardinia, Salerno, Paestum, and the Pontine Marshes in Italy. There were 69,000 cases during 1943-44 with 944,000 man-days lost. One and two-tenths percent of patients with malaria were evacuated to the United States.¹⁶ During the Sicilian campaign, the Seventh U.S. and British Eighth Armies lost, from malaria alone, the equivalent of the fighting effectiveness of two infantry divisions. In fact, there were more losses due to malaria than there were battle casualties; the Seventh U.S. Army reported 9,892 cases of malaria and 8,375 battle casualties and the British Eighth Army reported 11,590 and approximately 9,000, respectively.¹⁷

It is interesting to note that nearly all of the total malaria cases (32,796) in the European theater were imported by troops who had originally served in the North African theater. There were 4,806 cases of malaria among U.S. troops stationed in England before D-day 1944.

Altogether, during the period 1942-45, there were 492,299 cases of malaria, 410,727 of these occurring overseas; the total attack rate per 1,000 average strength per annum was 19.43 and was highest during 1943 and 1944 (table 53). Data on the noneffective rates for malaria are not presently available, but from 8 to 9 million man-days were estimated to have been lost because of malaria during 1942-45, at an average daily noneffective rate of 1 per 1,000 average strength; the estimated rate based on the average duration multiplied by the number of admissions and readmissions is 0.94.

Of the 492,299 cases of primary malaria occurring during 1942-45 with a rate of 19.43 per 1,000 average strength (table 54), the greatest number of cases occurred in the Southwest Pacific followed by the Central and South Pacific, the Mediterranean, and China-Burma-India theaters. The highest incidence rate, 98.46, occurred in the China-Burma-India theater.

¹⁴Recorded Interview, Office of the Surgeon General, 20 Apr. 1944, subject: Report of Medical Department Activities in China-Burma-India by Maj. John H. Grindlay, MC, Chief, Surgical Service, 20th General Hospital, India.
¹⁵Annual Report, Surgeon, India-China Division Air Transport Command, 1944.
¹⁶Golz, Harold H.: Human Malaria in the North African and Mediterranean Theaters of Operations, U.S. Army. [Official record.]
¹⁷Essential Technical Medical Data. North African Theater of Operations, U.S. Army, for October 1943.

454

TABLE 53.-Total attack rate¹for malaria in the U.S. Army, by area,² type of plasmodium, and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records]
[Rate expressed as number of cases per annum per 1,000 average strength]

¹Includes admissions for the first time for malaria, readmissions, and admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Area of admission to medical treatment, but not necessarily the area in which the disease was acquired.

TYPES OF MALARIA

Malaria due to Plasmodium vivax, Plasmodium falciparum, and Plasmodium malariae occurred in all theaters. Malaria caused by P. vivax had the highest incidence rates in the China-Burma-India theater, the Southwest Pacific and the Central and South Pacific Areas. The majority of the cases in the United States were of this type. The highest incidence rates due to P. falciparum occurred in the Middle East and the China-Burma-India the-

455

TABLE 54.-Attack rates¹ of malaria, all forms in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records] 

[Rate expressed as number of cases per annum per 1,000 average strength]

¹Consists of new admissions and readmissions for malaria as well as admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Area of admission to medical treatment, but not necessarily the area in which the disease was acquired. 
³Includes North Africa.
⁴Includes Alaska and Iceland.
⁵Includes cases on board transports.

ater. Ninety-seven percent of malaria acquired in Liberia was due to P. falciparum.¹⁸ P. malariae was found chiefly in the Mediterranean, the Southwest Pacific, China-Burma-India, and the Central and South Pacific Areas. The incidence rate of clinical P. malariae infections without classification was highest in China-Burma-India, the Southwest Pacific and the Central and South Pacific Areas.

P. vivax was the etiological agent in 341,276 cases; P. falciparum, in 51,280; P. malariae, in 1,877; and there were 3,444 cases with mixed type infections, or a total of about 397,000 in which plasmodia were identified. The remaining 94,442 cases were unclassified, the diagnosis being made on clinical signs and symptoms without microscopic verification. (See tables 55, 56, 57, 58, and 59.)

RELAPSE IN MALARIA

There are no accurate statistical data available on relapse rates. However, it is well known that malaria ascribed to P. vivax was prone to relapse under the therapeutic regimens in use during World War II. The relapse rate of malaria due to P. falciparum was markedly lower than that caused by P. vivax, although a significant number did relapse.

¹⁸Annual Report, U.S. Army Forces in Liberia, 1943.

456

TABLE 55.-Attack rates¹of vivax (tertian) malaria, in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records] 
[Rate expressed as number of cases per annum per 1,000 average strength]

¹Consists of new admissions and readmissions for malaria as well as admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Area of admission to medical treatment, but not necessarily the area in which the disease was acquired. 
³Includes North Africa.
⁴Includes Alaska and Iceland.
⁵Includes cases on board transports.

TABLE 56.-Attack rates¹ of falciparum (estivo-autumnal) malaria in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records]
[Rate expressed as number of cases per annum per 1,000 average strength]

¹Consists of new admissions and readmissions for malaria as well as admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Area of admission to medical treatment, but not necessarily the area in which the disease was acquired. 
³Includes North Africa.
⁴Includes Alaska and Iceland.
⁵Includes cases on board transports.

457

TABLE 57.-Attack rates¹ of malariae (quartan) malaria, in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records] 
[Rate expressed as number of cases per annum per 1,000 average strength]

¹Consists of new admissions and readmissions for malaria as well as admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Area of admission to medical treatment, but not necessarily the area in which the disease was acquired. 
³Includes North Africa.
⁴Includes Alaska and Iceland.
⁵Includes cases on board transports.

TABLE 58.-Attack rates¹of malaria, mixed type, in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records] 
[Rate expressed as number of cases per annum per 1,000 average strength]

¹Consists of new admissions and readmissions for malaria as well as admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Area of admission to medical treatment, but not necessarily the area in which the disease was acquired. 
³Includes North Africa.
⁴Includes Alaska and Iceland.
⁵Includes cases on board transports.

458

TABLE 59.-Attack rates¹ of malaria, unclassified and other,²in the U.S. Army, by area and year, 1942-45

[Preliminary data based on sample tabulations of individual medical records]
[Rate expressed as number of cases per annum per 1,000 average strength]

¹Consists of new admissions and readmissions for malaria as well as admissions for other causes, but in which malaria existed concurrently or developed subsequently.
²Other than vivax, falciparum, malariae, and mixed type.
³Area of admission to medical treatment, but not necessarily the area in which the disease was acquired. 
⁴Includes North Africa.
⁵Includes Alaska and Iceland.
⁶Includes cases on board transports.

The problem of relapses can best be illustrated by citing the experience in several areas. Approximately 30 percent of the troops of the 43d, 37th, 25th, and Americal Divisions had over four attacks of malaria by June 1944.¹⁹ Twenty percent of these relapses occurred within 2 months of the primary attack. The overall relapse rate in the China-Burma-India theater was estimated at 25 percent for vivax infections.²⁰ The 26th Field Hospital reported that approximately 60 percent of the malaria admissions were recurrences. Some of these patients had had 8, 10, and 14 previous attacks of malaria.²¹ Forty percent of 11,343 cases of malaria studied in the Mediterranean theater from 1 January to 1 December 1944 were recurrent cases. The relapse rate in this theater was estimated to be from 50 to 55 percent.²² In the Southwest Pacific Area, 392 cases of primary malaria were studied.

¹⁹Report, Capt. James E. T. Hopkins, MC, Surgeon, 3d Battalion Medical Detachment, 5307th Composite Unit (Provisional), 22 June 1944, subject: Preliminary Report of Physical and Mental Condition of Men and Officers of the 3d Battalion With Recommendations.
²⁰Essential Technical Medical Data, China-Burma-India Theater, for June 1944. 
²¹Annual Report, 26th Field Hospital, Persian Gulf Command, 1944.
²²See footnote 16, p. 453.

459

Of the total, 153 cases had relapses, the first relapse occurring on an average of 50 days after the primary attack. In 49 of the 153 cases, the second relapse occurred on an average of 54 days after the first relapse. In 18 of the 49 cases, 3 or more relapses each, occurred: 14 had 3 relapses, 2 had 4 relapses, and the remaining 2 had 5 relapses.²³

The following tabulation gives the percentage of relapses in a group of patients studied in Italy during January 1945.²⁴

Eighteen hospitals in the Mediterranean theater reported the number of relapses experienced by 3,512 recurrent cases of malaria, as follows:

DURATION OF HOSPITALIZATION

Data on the average duration of hospitalization for malaria in the entire Army were available only for the years 1942, 1943, and 1945, at the time this analysis was made.

The average stay in hospital and quarters varied from a low of 13.6 days in 1945 to a high of 22.2 days in 1943 (table 60). Malaria due to a mixed type of infection required a longer period of hospitalization than did malaria due to a single species of Plasmodium. It is perhaps significant that the duration of hospitalization for fever of undetermined origin was much less than that due to malaria.

²³Essential Technical Medical Data, Southwest Pacific Area, for July 1944.
²⁴Essential Technical Medical Data, Mediterranean Theater of Operations, for February 1945.

460

TABLE 60.-Average number of days in hospital and quarters for admissions and readmissions due to malaria and fever of undetermined origin, U.S. Army, 1942, 1943, and 1945

[Preliminary data based on sample tabulations of individual medical records]

DEATHS DUE TO MALARIA

There were 302 deaths due to malaria during the period 1942-45; 292 of these deaths occurred among oversea admissions; of this total, 157 deaths occurred in Pacific areas: 113 deaths recorded for the Southwest Pacific and 44 deaths for the Central and South Pacific Areas, table 61. The annual rates per 100,000 average strength were highest in China-Burma-India followed by the Middle East, Southwest Pacific, and Latin American areas. The rates varied from year to year, the highest, 20.19 per 100,000 average strength, occurring in the China-Burma-India theater during 1943.

The majority of deaths, 125, and the highest annual rate per 100,000 average strength, 0.49, were due to P. falciparum. P. vivax accounted for 68

TABLE 61.-Deaths due to malaria, all forms,¹ in the U.S. Army, by area of admission and year of death, 1942-45 

[Preliminary data based on tabulations of individual medical records] 
[Rate expressed as number of deaths per annum per 100,000 average strength]

¹There were no deaths due to malariae (quartan) malaria. 
²Includes North Africa.
³Includes Alaska and Iceland.
⁴Includes one death each year on transports, 1943, 1944, and 1945, respectively.

461

deaths and mixed infections for 6. No deaths were caused by P. malariae. There were 103 deaths due to unclassified malaria. (See tables 62, 63, 64, and 65.)

TABLE 62.-Deaths due to vivax(tertian) malaria, in the U.S. Army, by area of admission and year of death, 1942-45

[Preliminary data based on tabulations of individual medical records] 
[Rate expressed as number of deaths per annum per 100,000 average strength]

¹Includes North Africa.
²Includes Alaska and Iceland.

TABLE 63.-Deaths due to falciparum (estivo-autumnal) malaria, in the U.S. Army, by area of admission and year of death, 1942-45

[Preliminary data based on tabulations of individual medical records] 
[Rate expressed as number of deaths per annum per 100,000 average strength]

¹Includes North Africa.
²Includes Alaska and Iceland.
³Includes one death each year on transports, 1943, 1944, and 1945, respectively.

462

TABLE 64.-Deaths due to malaria, mixed type, in the U.S. Army, by area of admission and year of death, 1942-45

[Preliminary data based on tabulations of individual medical records]
[Rate expressed as number of deaths per annum per 100,000 average strength]

TABLE 65.-Deaths due to malaria, unclassified and other,¹ in the U.S. Army, by area of admission and year of death, 1942-45

[Preliminary data based on tabulations of individual medical records]
[Rate expressed as number of deaths per annum per 100,000 average strength]

¹Other than vivax, falciparum, malariae, and mixed type. 
²Includes North Africa.
³Includes Alaska and Iceland.

463

SUMMARY

The role of malaria in military campaigns was reemphasized once more during World War II. The magnitude of the problem is illustrated by a brief presentation of statistical data giving the incidence of malaria, the types of malaria, the relapse problem, and the number of deaths due to malaria. It is indeed a tribute to the Medical Department of the U.S. Army, that the menace of malaria did not more seriously interfere with military operations.

RETURN TO TABLE OF CONTENTS