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Chapter 23 - Amebiasis

Contents

Parasitic Infections


CHAPTER XXIII

Amebiasis

Henry E. Meleney, M. D.

Before World War II, amebiasis lead not been a serious problem ill the United States Armed Forces, except during the Philippine Insurrection following the Spanish-American War and in one epidemic oil the Mexican border in 1916. Attention has been called to these two episodes by Craig.1 During World War I among American Armed Forces,2 only 38 out of 934 laboratory tested cases of dysentery were proved to be of amebic; origin. The only indication of acquisition of infection with Endamoeba histolytica overseas was furnished from a fecal survey at Debarkation Hospital No. 3 by Kofoid, Kornhauser, and Plate3 in which they found 12.8 percent of 2,300 overseas troops infected, as compared with 4.3 percent of 576 troops who had not been overseas.

The British lead considerable experience with amebiasis during World War I especially in the Gallipoli campaign and in the Middle East. This led to intensive studies of intestinal amebiasis of man and to the discovery of two previously unrecognized species, Endolimax nana4 and Dientamoeba fragilis.5 Within the next 20 years, surveys of the prevalence of amebiasis were made ill many parts of the world including several ill the United States, and Craig estimated that the over-all prevalence in this country was about 10 percent of the population with wide variations in different regions.

Many other important contributions to the knowledge of amebiasis were made between the First and Second World Wars. In 1925, Boeck and Drbohlav 6 devised a practical culture medium for E. histolytica, and this was improved upon by Dobell and Laidlaw. 7 In 1929, Craig 8 described a comple-

1 Craig, Charles F.: The Etiology, Diagnosis, and Treatment of Amebiasis. Baltimore. Williams and Wilkins Co., 1944. (2) Craig, C. F.: The Occurrence of Endamebic Dysentery in the Troops Serving in the El Paso District From July 1916 to December 1916. Mil. Surgeon 40: 286-302; 423-434, March and April 1917.

2 The Medical Department of the United States Army in the World War. Washington: Government Printing Office, 1926, vol. VI, p. 1101.

3 Kofoid, C. A., and Kornhauser, S. I., and Plate, J. T.: Intestinal Parasites in Overseas and Home Service Troops of the U. S. Army; With Especial Reference to Carriers of Amoebiasis. J. A. M. A. 72: 1721-1724, June 1919.

4 Wenyon, Charles M., and O'Connor, Francis W.: Human Intestinal Protozoa in the Near East.London: John Bake, Sons and Danielsson, 1917.

5 Jepps, M. W., and Dobell, C.: Dientamoeba fragilis, a New Intestinal Amoeba From Man. Parasitology 10: 352-367,1917-18.

6 Boeck, Ii'. C., and Drbohlav, J.: The Cultivation of Endamoeba histolytica. Am. J. Hyg. 5: 371-407, July 1925.

7 Dobell, C., and Laidlaw, P. P.: On the Cultivation of Entamoeba histolytica and Some Other Entozoic Amoebae. Parasitology 18: 283-318, September 1926.

8 Craig, C. F.: The Technique and Results of a Complement Fixation Test for the Diagnosis of Infections with Endamoeba histolytica.Am. J. Trop. Med. 9: 277-296, September 1929.


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ment fixation test for amebiasis. Dobel l9 I worked out the life cycle of E. histolytica in culture. Studies of pathogenicity were made in kittens10 and dogs,11 and the influence of associated bacteria and diet received attention. The Chicago epidemic of 193312 emphasized the importance of contaminated water as a source of infection. Studies of water purification indicated that cysts of E. histolytica are more resistant to chlorination than are fecal bacteria.13 Chemotherapy was improved by the introduction of carbarsone and the iodohydroxyquinoline compounds, chiniofon, Vioform, and Diodoquin. The zinc sulfate flotation technique for concentration of cysts in fecal diagnosis was introduced.14

INCIDENCE

General Considerations

The incidence of amebiasis in the Army included mild cases of amebic dysentery and amebic colitis as well as those with the classical picture of dysentery.Available statistics for the Army have been obtained from sample tabulations of primary and secondary diagnoses on individual medical record cards and include admissions for amebic dysentery as well as cases admitted for different diagnosis but in which amebic dysentery existed concurrently or developed subsequent to admission. Although dysentery is the most prominent clinical manifestation of amebiasis and is a good measure of its importance as a cause of noneffectiveness, it represents only a small proportion of the infections with E. histolytica. This is important because these infections are usually of long duration, probably many years, and are the source of spread to contacts under suitable circumstances. Furthermore, symptomless infections may give rise to clinical manifestations only after a long period of time.

Preliminary statistical data on the incidence (total cases) of amebic dysentery in the United States Army for the years 1942-45 by area, as calculated from samples of individual medical records, are presented in tables 84, 85, 86, and 87. These estimates, though subject to considerable sampling error, furnish comparative information of value concerning the relative importance

9 Dobell, C.: Researches on the Intestinal Protozoa of Monkeys and Man. II. Description of the Whole-Life-History of Entamoeba histolytica in Cultures. Parasitology 20: 365-412, December 1928.

10 Meleney, H. E., and Frye, W. W.: The Pathogenicity of Endamoeba histolytica.Tr. Roy. Soc. Trop. Med. & Hyg. 29: 369-379, January 1936.

11 Faust, E. C., and Kagy, E. S.: Studies on the Effect of Feeding Ventriculin, Liver Extract and Raw Liver to Dogs Experimentally Infected With Endamoeba histolytica.Am. J. Trop. Med. 14: 235-255, May 1934.

12 Epidemic Amebic Dysentery: The Chicago Outbreak of 1933. Nat. Inst. Health Bull. No. 166, pp. 1-187, March 1936.

13 Chang, S. L., and Fair, G. M.: Viability and Destruction of the Cysts of Entamoeba histolytica.J. Am. Water Works Assoc. 33: 1705-1715, October 1941.

14 Faust, E. C., D'Antoni, J. S., Odom, V., Miller, M. J., Peres, C., Sawitz, W., Thomen, L. F., Tobie, J., and Walker, J. H.: A Critical Study of Clinical Laboratory Techniques for the Diagnosis of Protozoan Cysts and Helminth Eggs in Feces. Am. J. Trop. Med. 18: 169-183, March 1938.


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TABLE 84.- Incidence of amebic dysentery in the U.S. Army, by area and year, 1942-45


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of amebic infection as a cause of nonefectiveness in the Army. The following observations on these figures are of interest:

1. The over-all rate of 1.34 per 1,000 average strength is low as compared with that of many other infections requiring medical attention.

2. The rate each year more than doubled the rate of the previous year.

3. The rate for troops in the United States was uniformly very low, increasing only in 1945 when many overseas troops had returned to this country.

4. Among the overseas theaters, the China-Burma-India theater had by far the highest rate, with the Middle East theater second, and the combined Pacific theaters third. The rates in the other overseas theaters never reached important proportions.

TABLE 85.-Admissions for amebic dysentery in the U. S. Army, by area and year, 1944-45


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TABLE 86.- Admissions for amebic dysentery carrier in the U. S. Army, by area and year, 1942-45


490

TABLE 87.-Incidence of amebic dysentery carrier state in the U. S. Army, by area and year, 1944-45

AMEBIASIS IN OVERSEAS THEATERS AND AREAS

India-Burma Theater

Amebic dystentery was recognized and reported in Army units soon after they began to arrive in the theater in the summer of 1942.15 It increased moderately in incidence during 1943 and more in 1944 reaching a peak of 50 per annum per 1,000 average strength in August and September 1944. This represented 675 and 884 cases, respectively, in these 2 months. In 1945, the incidence decreased considerably when intensive measures to prevent diarrheal diseases became effective. It is interesting that the incidence of bacillary dysentery was almost consistently somewhat lower than that of amebic dysentery throughout the entire period of operations in this theater. Both of these infections, however, were greatly overshadowed by acute diarrhea of unrecognized etiology, which reached a peak incidence of 215 per annum per 1,000 strength in July 1944.

Insanitary conditions conducive to the transmission of amebiasis existed almost everywhere in the theater. The medical and sanitary departments

15 Van Auken, H. A.: A History of Preventive Medicine in the U. S. Army Forces of the India-Burma Theater, 1942-45. [official record.]


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were not prepared to deal with this complicated problem. Most medical officers had had no practical experience in dealing with the type of environmental conditions which existed and could not foresee or detect the hidden sources of infection. Directives for prevention and control were general in nature and not specifically adapted to the local situation. Equipment for mess sanitation, fly control, and water purification was inadequate or not efficiently used. Facilities for accurate diagnosis were provided only at the 9th Medical Laboratory and at some of the general hospitals.

As experience was gained by investigation of conditions associated with high incidence or epidemics of diarrheal diseases in individual units, unsupervised native foodhandlers appeared to be the greatest source of infection, although surveys for E. histolytica regularly showed a much lower incidence of infection in natives than in American personnel. In two instances, however, contaminated water supplies appeared to be the source of outbreaks of amebic dysentery. Other possible sources of infection were difficult to evaluate.

In June 1944, the Preventive Medicine Service of the Surgeon General's Office. sent a Sub-Commission on Dysentery of the Army Epidemiological Board to Calcutta to make an intensive study in that area and in the Ledo area of Assam. The Sub-Commission16 reported that at the 112th Station Hospital in Calcutta during July 1944 about one-fourth of the admissions for diarrhea or dysentery were amebic. In Advance Section 3 (Assam) for the year ending 30 September 1944, there had been 444 hospital admissions for amebic dysentery. In one combat unit, one-third of the first 150 admissions were for amebic dysenter. The Sub-Commission concluded that, from the standpoint of days lost and disability, amebic dysentery was the most important of the diarrheal diseases.Trained clinical and laboratory personnel and equipment for accurate diagnosis were inadequate, and sources of infection were poorly controlled.The chief source appeared to be native foodhandlers, followed by water, flies, and food in order of importance. Instruction of personnel was started, and recommendations were made for more rapid and accurate diagnosis, additional trained personnel, thorough treatment, and the control of possible sources of infection.

A preventive medicine section was set up in the Office of the Chief Surgeon and certain control activities were initiated through the theater commander. Among these were the assignment of a special sanitary officer to check mess sanitation through the theater, the issuance of letters of inquiry, to orgailizations with high diarrheal rates, the inauguration of a better method for the distribution of sanitation supplies, and the preparation of a circular on water supplies.

The complete program of control instituted in the fall of 1944 included the issuance of directives, periodic inspections, provisions of necessary supplies, education of commanders and lectures to personnel, investigations of undue increase of cases of diarrhea, and the placing of responsibility for control on unit commanders. A theater laboratory consultant was appointed to raise

16 Progress and Final Report, Sub-Commission on Dysentery, Army Epidemiological Board, 20 Nov. 1944.


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the standards of diagnostic performance throughout the theater, and the 9th General Laboratory gave apprentice training and longer courses of instruction to laboratory officers and enlisted men.

The problem of symptomless carriers of E. histolytica among American personnel and natives received considerable attention. Beginning during the summer of 1944, numerous surveys were conducted by the 9th Medical Laboratory and by local hospitals and dispensaries. In some instances, the entire personnel of an organization was examined. Infection rates varied from 3 to 33 percent. Rates tended to be higher in units having many cases of diarrhea. The lowest recorded rates may have been due partly to lack of training of laboratory personnel. The highest rate was at the 24th Station Hospital where an epidemic of amebic dysentery among the hospital personnel was traced to a contaminated water supply.

Most units had their foodhandlers examined periodically when laboratory facilities were provided and found that the elimination of infected personnel from the kitchens was followed in a number of instances by a definite drop in the incidence of diarrhea.

The intensive control measures instituted in the fall of 1944 are reflected more in the lower reported incidence of common diarrhea in the summer of 1945, which was only about one-third of that in 1944, than in the incidence of amebic dysentery which reached a rate of 37 per 1,000 per annum in July 1945 as compared with a rate of 50 per 1,000 per annum in August and September 1944. This lesser decline is to be expected because of the insidious and chronic nature of amebic infection.

In the India-China Division of the Air Transport Command, water supplies in the China stations were unsatisfactory, and coolie labor increased the hazard of contamination. A report by Maj. Clifton W. Bovee, SnC, in July 1945, to the division surgeon, described the deficiencies that still existed and made recommendations for each of the bases. Basic water supply systems or diatomaceous silica filters provided safe drinking water, but water supplied washrooms, showers, and some messes remained highly inacceptable. Additional mechanical equipment and simple distribution systems were required.

Southwest Pacific Area

With the invasion of individual islands, insanitary conditions were encountered and contact with native populations occurred which were conducive to the development of a high infection rate with E. histolytica.

An illustration of the experience of one division is contained in a report by Maj. Harry J. Bennett, SnC, on a survey made of intestinal parasites in the 37th Infantry Division.17 The division arrived in the Fiji Islands from the United States and New Zealand in June and August 1942. It was transferred to Guadalcanal in April 1943, participated in the New Georgia campaign from

17 Report, Maj. Harry J. Bennett, SnC, to Chief Malariologist, Headquarters, U. S. Army Forces, Far East, 18 Nov. 1944, subject: Intestinal Parasite Survey for the 37th Infantry Division.


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July to September 1943, then returned to Guadalcanal for 1 month, and arrived in Bougainville in November 1943. The first six cases of amebic dysentery were diagnosed on Guadalcanal in May 1943. There was no great increase in cases until after the division reached Bougainville. Beginning in January 1944, when 17 cases occurred, there was an increase to 67 cases in July, a rate of 55 per 1,000 per annum. Between 1 November 1943 and 1 November 1944, 460 cases of amebic dysentery were admitted to hospitals. A stool survey of 1,072 individuals, mostly kitchen personnel from the various units of the division, was conducted from July to September 1944, and 27.3 percent were found to harbor E. histolytica. Since only one specimen was examined from most individuals, it was estimated that the actual prevalence was at least 50 percent. Analysis of sanitary conditions under which the division had operated suggested that no single source of infection could be incriminated but that flies, inadequate sanitary facilities, and polluted water all probably played a part in building up a high incidence of infection.

Another illustration is the experience of the 81st Infantry Division which invaded the island of Peleliu, one of the Palau Islands. A high incidence of amebic dysentery led to a preliminary stool survey by Capt. E. C. Nelson, SnC 18 while the division was still on the island. On a single stool examination of 2,210 troops of a regiment, 30 percent were found to harbor E. histolytica; the prevalence in different companies varied from 17 to 44 percent. When the division returned to New Caledonia, the survey was continued with 14,534 (88 percent) of the personnel receiving 1 stool examination. An over-all prevalence of 18.7 percent was found. This study was reported by Murray, Winter, and Sears.19 Captain Nelson investigated the conditions possibly responsible for the high incidence of cases shortly after arrival on the island and concluded that flies were probably the principal source of infection since the water supply was found to be protected from surface contamination and individual food rations were used. The incidence of infection was, in general, highest where the fly population was greatest. One course of specific treatment of all infected personnel reduced the incidence in these individuals to 5.1 percent.

Following the invasion of the Philippine Islands, beginning with Leyte in October 1944, there was an increase in the number of clinical cases of amebiasis through the quarter ending June 1945, after which the number of reported cases declined. This is indicated by the following data from the quarterly reports of the 116th Station Hospital, which was located on Leyte and served the XXIV Corps, the 81st Division, and later the IX Corps and other troops assigned to Base K:

1945

Cases of amebiasis

January-March

330

April-June

761

July-September

215

October-November

72


18 Essential Technical Medical Data, Headquarters, Pacific Ocean Area, March 1945, inclosure 7.
19 Essential Technical Medical Data, Headquarters, South Pacific Base Command, March 1945.


494

Amebiasis was considered the most serious disease problem in the Philippine area except for infectious hepatitis. The increase in the number of new cases of amebiasis and the rates per thousand per annum for Base K during the first 5 months of 1945 are shown in the following tabulation: 20

Cases

Rates

January

275

4.57

February

432

7.20

March

822

11.37

April

911

15.32

May

999

16.52

In the Philippines, contact of military personnel with the civilian population was greater than in most of the Pacific islands. In Manila, the destruction of buildings and the general breakdown of sanitation added to the conditions favorable for the transmission of amebiasis. The following measures were taken to control amebic dysentery on Base K:

1. All water was treated before consumption by boiling or filtration and then by chlorination. Wells were cased and properly located.

2. Fly control was rigidly enforced by screening and spraying with DDT.

3. Civilians were prohibited from any food handling.

4. The preparation and use of ice was controlled.

5. Messgear was dipped in boiling water before use.

6. Cases and carriers of amebic infection were excluded from food handling.

7. Foodhandlers received stool examinations monthly and were instructed in personal sanitation.

8. Temporary kitchen police were instructed in personal sanitation.

9. Military personnel were forbidden to live with civilians.

10. Civilians were not permitted to live within unit areas.

11. Animal pets were discouraged.

12. Consumption of food from civilian sources was forbidden, and green vegetables grown locally were not eaten uncooked.

In the Eighth U. S. Army, which ultimately went from the Philippines to Japan, amebiasis was a relatively unimportant cause for hospitalization at the beginning of 1945 but by June increased to an admission rate of 40 per annum per 1,000 average strength.21 It was believed that a large proportion of the cases resulted from the practice among Army personnel of eating food and drinking untreated water in Filipino homes and restaurants. By means of the issuance of directives and personal visits by medical officers from Army headquarters, an intensive sanitary control program was put into effect in all operational areas. This was followed by a drop in admissions in July to a rate of 9.7 per annum per 1,000, with no later significant increase, and a continued decline after arrival in Japan.

In Hawaii and the mid-Pacific islands, amebiasis was apparently not an important infection.

20 Essential Technical Medical Data, Headquarters, U. S. Army Forces, Pacific, July 1945.

21 Annual Report, Surgeon, Headquarters, Eighth U. S. Army, Southwest Pacific Area, 1945.


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Middle East Theater

The data in tables 84, 85, 86, and 87 indicate that amebiasis was not so prevalent in this theater as in the China-Burma-India theater and that it reached a peak of 11.33 per 1,000 per annum in 1943, after which it declined. A report on amebiasis from the 38th General Hospital for the period November 1942 to November 1944 stated that 464 cases of amebiasis had been admitted to the hospital during that period. The highest rates of admission were in April and May 1943. About one-fourth of these were classed as carriers; the remainder had chronic or acute symptoms. Of the hospital personnel, 816 complained of abdominal symptoms during this period, and 144 (17.8 percent) were found to be suffering from symptomatic amebiasis. Purged stools of foodhandlers were examined monthly. None was found infected until the hospital had been in that locality for about a year. Of 77 individuals, 28 (36.4 percent) were found infected on one of the examinations. Twenty-two of these infected persons were entirely symptom free.22

A report of the Middle East Service Command, 1 June 1944, gave results of a survey of 147 foodhandlers at Camp Russell B. Huckstep. A prevalence of 18.3 percent of infection with E. histolytica was found.

Mediterranean Theater

Amebiasis was a minor problem in the Mediterranean theater. A report on dysentery and common diarrheas by Maj. H. M. Hurevitz, MC, in June 1945, indicated that the admissions to hospitals and quarters in the entire theater for protozoal dysentery totaled 156 cases in 1943 and 851 in 1944. Some of the cases in 1944 were asymptomatic, having been admitted only because E. histolytica had been found in the feces. Surveys of military personnel had revealed a prevalence in different units of only 2 to 11 percent. Many patients with diarrhea or dysentery in whom E. histolytica was found were considered to be suffering from other infections.

The potential menace of diarrhea and dysentery in the forces in North Africa was predicted by Col. Perrin H. Long, consultant in medicine to the surgeon of the Mediterranean theater, in January 1943.23 He made recommendations to the Deputy Surgeon, Allied Force, for sanitary-control procedures, but these were not acted upon at that time. In May, when flies became abundant, bacillary dysentery broke out in American troops in all areas of North Africa. Investigation indicated that the outbreaks were due to bad sanitation in certain units. This led to the publication of a theater circular which dealt with the measures to be employed in the control of dysentery and stressed command responsibility for sanitation.24 Supplies for flyproofing

22 Tallant, E. J., and Maisel, A. L.: Amebiasis Among the American Armed Forces in the Middle East. Arch. Int. Med. 77: 597-613, June 1946.

23 Long, Perrin H.: A Historical Survey of the Activities of the Section of Preventive Medicine, Office of the Surgeon, Mediterranean Theater of Operations, United States Army, 3 January 1943 to 15 August 1943. [Official record.]
24 Circular No. 106, Headquarters, North African Theater of Operations, United States Army, 9 June 1943.


496

were released from engineer stocks; sanitary inspectors, armed with punitive powers, visited the base sections to check up on sanitation; and great efforts were made to bring fly breeding under control. As a result, the admission rates for diarrhea and dysentery which had reached 445 per 1,000 per annum in June were cut to 213 per 1,000 per annum in July despite the invasion of Sicily early in that month. Measures specifically directed against the transmission of amebiasis emphasized prohibition of the. use of raw fruits and vegetables without prior sterilization.

In 1944, with the shifting of the campaign to Italy, control measures against diarrheal diseases were successfully continued. 25

European Theater

Amebiasis was not a serious problem in the European theater. 26 The total number of admissions for the years 1942 to 1945 was 1,637, an annual rate, of 0.37 per 1,000 average strength. This is broken down further into an annual rate for 1942 of 0, for 1943 of 0.14, for 1944 of 0.36, and for 1945 of 0.42 per 1,000 average strength (table 84). Very few cases occurred in troops in England; the number increased with the invasion of France. This increase appears to have been partly due to infections acquired in the Mediterranean theater by troops who invaded Southern France. Edson, Ingegno, and D'Albora 27 reported 39 cases of amebiasis from a United States Army general hospital in North Ireland during a period of 10 months. All patients had symptoms and physical signs. Twenty-six were members of one division (presumably the 5th) which was composed largely of troops from the Southern United States who had been through maneuvers in Tennessee and Louisiana. The authors suggested that the original infections had occurred in the United States and that some had been acquired subsequently from contact with carriers. A survey of 162 foodhandlers with the 5th Infantry Division revealed 18.5 percent positive for E. histolytica on one stool examination. A second survey of a random selection of troops by another laboratory, revealed a prevalence of 19 percent.

A survey of troops from a division in England showed a rate of 16.1 percent for E. histolytica, indicating that the infection was more common than is estimated in the civilian population of the United States. Cases of diarrhea in which E. histolytica was identified were classed as amebic dysentery. It was considered probable that some of these cases were actually cases of bacillary dysentery or common diarrhea and that the actual incidence of active amebic dysentery was less than that reported.

25 Annual Report, Surgeon, Mediterranean Theater of Operations, United States Army, 1944, vol. 2.

26 Gordon, J. E.: A History of Preventive Medicine in the European Theater of Operations, U. S. Army, 1941-45, pt. III, sec. 2. [Official record.]

27 Edson, J. N., Ingegno, A. P., and D'Albora, J. B.: Amebiasis: A Report of Thirty-nine Cases Observed in an Army General Hospital Stationed in Northern Ireland. Ann. Int. Med. 23:960-968, December 1945.


497

PREVENTION AND CONTROL

At the request of the Chief, Preventive Medicine Service, Office of the Surgeon General, the Subcommittee on Tropical Diseases of the National Research Council early in 1941 prepared a directive entitled "Notes on the Treatment and Control of Certain Tropical Diseases," which was issued by the Office of the Surgeon General on 9 June 1941 as Circular Letter No. 56. A revision of this directive issued on 2 February 1943 as Circular Letter No. 33 contained data on the prevention of amebiasis including the necessity for superchlorination or boiling of water to kill cysts, avoidance of raw fruits and vegetables wherever exposed to human excreta, exclusion of infected persons from food handling, and control of flies and cockroaches.Reference was also made to AR 40-205 and AR 40-210.Circular Letter No. 33 was superseded by TB MED 159, Amebiasis, issued May 1945, which contained a section on prevention, including considerable detail concerning mess sanitation, foodhandlers, water purification, excreta disposal, and fly control by the use of DDT.

In general, the measures taken to prevent amebiasis in individual areas of military operation were part of those taken to prevent all forms of gastrointestinal infection.The only additional requirement for the prevention of amebiasis was based upon the fact that a higher concentration of residual chlorine is required to kill the cysts of E. histolytica than to kill bacteria in water. Superchlorination and subsequent dechlorination of water in Lyster bags and canteens was introduced to some extent in 1944 and 1945, but its effect on the incidence of amebiasis cannot be determined. Several directives were issued by theater surgeons 28 describing the disease and its modes of transmission, and methods of diagnosis, treatment, and prevention.

The effective measures of control of amebiasis seem to have been (1) the provision of safe water supplies, (2) the exclusion of native foodhandlers, (3) the examination of military foodhandlers and the exclusion of those found to be infected, (4) the sanitary disposal of human excreta, (5) the prohibition or sterilization of raw fruits and vegetables, (6) the control of flies by screening and DDT spraying, (7) the prohibition of eating in native homes or restaurants, and (8) the enforcement of individual sanitary discipline.

A survey of single, normally passed stool specimens from 4,000 men at the time of separation from military service was made at Fort McPherson, from January to May 1946.29 The specimens were examined by the direct smear and zinc sulfate flotation techniques and doubtful specimens were checked by iron-hematoxylin stain. E. histolytica was identified in 14.3 percent of the specimens. The, prevalence by area of service is shown in table 88.


28
(1) Circular No. 9, Office of the Surgeon, Headquarters, U. S. Army Forces, India-Burma Theater, 2 Apr. 1945, subject: Amebiasis. (2) Technical Memorandum No. 20, Office of the Chief Surgeon, Headquarters, U. S. Army Forces in the Far East, 24 Nov. 1944, subject: Amebiasis: Amoebic Dysentery.

29 Survey of Intestinal Parasites in Soldiers Being Separated from Service. Bull. U. S. Army M. Dept. 6: 259-262, September 1946.


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TABLE 88.-Prevalence of infection with E. histolytica1 among 4,000 troops from various areas, at time of separation from service, Fort McPherson, Ga., January to May 1946

The results of this survey coincide in general with the clinical and laboratory experience in overseas theaters and indicate that many infections acquired overseas were introduced into this country. 30

RESEARCH ON WATER PURIFICATION

The importance of water as a vehicle for the transmission of E. histolytica was emphasized by the epidemic of amebiasis in Chicago in 1933. Although some work was done before World War II on the effectiveness of chlorine in killing the cysts of E. histolytica, Chang and Fair 31 in 1941 were the first to demonstrate the degree to which cysts were resistant to chlorination under various conditions of water quality. Their work was confirmed by Brady, Jones, and Newton 32 in 1943. Later studies by Fair 33 demonstrated that, if calcium hypochlorite solution were used in Lyster bags, a residual chlorine of 7.5 parts per million would be required at a temperature of 10 0C. with a 30-minute contact to assure the killing of cysts. Under these conditions, other chlorine demands of the water would probably raise the initial chlorine demand to 25 to 30 parts per million; acidification would also be necessary to ensure a desirable pH value of the water, and, in order to produce a palatable water, dechlorination by sodium sulfite in the receiving vessel would be necessary. The use of halazone (p-dichlorosulfamidobenzoic acid) tablet's presented an even greater problem because of their slow dissolving time and the more objectionable taste which they convey to water. These difficulties reduced the practicability of employing chlorine compounds to disinfect water in canteen quantities, although

30 An estimate of the prevalence of amebiasis among veterans of World War II may be obtained from records of veterans hospitals showing the number of cases discharged from the hospitals since the war. It was reported at a meeting of Regional Consultants on Tropical Medicine, Veterans' Administration, held at Savannah, Ga., on 5 November 1950, that during the years 1945-48, a total of 3,673 patients treated for amebiasis were discharged. There was a rapid increase in the number of cases diagnosed after the return of troops from overseas, and the increase was continuous through 1949.

31 See footnote 13, p. 486.

32 Brady, F. J., Jones, M. F., and Newton, W. L.: Effect of Chlorination of Water on Viability of Cysts of Endamoeba histolytica.War Med. 3: 409-419, April 1943.

33 Fair, (I. M.: Interim Report No. 4; Disinfection of Water; Contract OEMemr-251. NRC Bull. Sanit. Eng. Div. 12 July 1945, pp. 195-219.


499

provision for hyperchlorination and dechlorination was made in some areas of military operation.

For these reasons, Fair and his associates investigated other halogens and found that iodine was a more useful cysticidal agent. The first iodine tablet developed contained Bursoline, a mechanical mixture in the proportion of 2 moles of diglycine hydriodide to 1 mole of elemental iodine. On solution in water, tablets containing this mixture liberated free iodine. This element has the advantages over chlorine of not being so easily hydrolyzed and not reacting with ammonia or organic nitrogenous substances to form iodoamines.34 For field disinfections it was found that, with a contact time of 10 minutes, 4 parts per million of free iodine were required to kill 60 cysts per ml. at 23 Centigrade. A dose of 7.5 to 8 parts per million was considered sufficient to take care of the great majority of waters and leave sufficient residual for disinfecting action in 10 minutes, unless the water was very cold. Tablets containing Bursoline, disodium dihydrogen pryo-phosphate as an acid-buffering agent, and filler were prepared for use in canteens, and field tests showed that they were satisfactory because of their stability, rapid solution, and the lack of disagreeable taste of the treated water. There was also no evidence that iodine, in the dosage employed, would be harmful to consumers. Bursoline tablets were, therefore, produced on a small commercial scale and were used to some extent in the India-Burma and Pacific theaters late in the war.

Further investigation by Fair and his associates indicated that Globaline (crystalline tetraglycine hydroperiodide) could replace the Bursoline mixture and therebv reduce the amount of inactive iodine added to the water. Buffered tablets of this compound, which would liberate 8 mg. of iodine per tablet, were found to be stable under normal conditions of storage and use. They dissolved in less than a minute and disinfected most waters in 10 minutes with the use of one tablet per canteen. Two tablets were required for highly colored waters and 20 minutes for disinfection of very cold water. High turbidity, alkalinity, ammonia, urea, and salt had no appreciable effect on the disinfecting efficiency. Field tests in the armed services showed great superiority of Globaline over chlorine compounds because of palatability, rapidity of disinfection, and convenience.

Synthetic detergents were tested for cysticidal activity under contract with the Office of Scientific Research and Development by Fair, Chang, Taylor, and Wineman 35 and by Kessel and Moore.36 A number of cationic compounds were found to be effective.Fair reported that Ceepryn (1-n-hexadecyl pyridinium chloride) and Fixanol (cetyl pyridinium bromide) were cysticidal in water at concentrations of 25 to 50 parts per million, but that it was not practical to

34 Fair, G. M.: Water Disinfection and Allied Subjects. In United States Office of Scientific Research and Development: Advances in Military Medicine. Boston: Little and Brown Co., 1948, vol. 11, pp. 520-531.

35 Fair, G. n1., Chang, S. L., Taylor, M. P., and Wineman, M. A.: Destruction of Water-Borne Cysts of Endamoeha histolytica by Synthetic Detergents. Am. J. Pub. Health 35: 228-232, March 1945.

36 Kessel, J. F., and Moore, F. J.: Emergency Sterilization of Drinking Water With Heteropolar Cationic Antiseptics. Am. J. Trop. Med. 26: 345-350, March 1946.


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use them in the Armed Forces because at that concentration they foam badly and have a bitter taste.

The effectiveness of ozone as a cysticidal agent was investigated during the war by Kessel and his coworkers,37 and more recently by Newton and Jones.38 In laboratory tests they found ozone more active than chlorine and not influenced by hydrogen ion concentration or organic matter, but difficulty of production and rapid dissipation in water, leaving no residual, made it unsuitable for practical application.

Ultraviolet light as a cysticidal agent was also tested on a small scale during the war by Stoll, Ward, and Mathieson at the Naval Medical Research Institute.39Although it was found to be effective under experimental conditions, it did not appear to be a practical agent for the purification of military water supplies.

The efficiency of the portable sand filters of the Army for the removal of cysts of E. histolytica from water was investigated by the Corps of Engineers during the war in cooperation with the National Institutes of Health.40 It was found that when these filters were operated at the rate for which they were designed they allowed some cysts to pass through. This danger was increased by the tendency to operate the filters at a higher rate when a larger quantity of water was required. Diatomaceous earth was found to be efficient in removing all cysts, irrespective of the nature of the water, at flow rates as high as 7 gallons per square foot per minute. Portable filters of this type were manufactured and were used to a small extent during the latter part of the war in the China section of the Air Transport Command.

RESEARCH ON SEWAGE TREATMENT

Cram41 studied the survival of cysts of E. histolytica under experimental conditions simulating sewage treatment processes in common use. The cysts were not removed by primary settling, but passed out in the effluent, and also passed through trickling filters and survived activated sludge treatment. They were removed by alum floc precipitation during secondary settling, and also by intermittent sand filtration. They did not survive sludge digestion. These results indicated that effluents from sewage disposal plants would be likely to contain cysts of E. histolytica which might be transported for long distances in streams.

37 Kessel, J. F., Allison, D. K., Kaime, M., Quiros, M., and Gloeckner, A.: The Cysticidal Effects of Chlorine and ozone on Cysts of Endamoeba histolytica, Together With a Comparative Study of Several Encystment Media. Am. J. Trop. Med. 24: 177-183, May 1944.

38 Newton, W. L., and Jones, M. F.: The Effect of Ozone in Water on Cysts of Endamoeba histolytica. Am. J. Trop. Med. 29: 669-681, September 1949.

39 Naval Medical Research Institute, Research Project X-110, Report 5, 2 Feb. 1945, subject: The Effect of Ultraviolet Radiation on Cysts of Endamoeba histolytica.

40 (1) Black, H. H.: Army Field Water Supply Developments.Am. J. Pub. Health 34:697-710, July 1944. (2) Engineer Board, Corps of Engineers, Report 834, 3 July 1944, subject: Efficiency of Standard Army Water Purification Equip ment and of Diatomite Filters in Removing Cysts of Endamoeba histolytica from Water (3) Newton, W. L.: Water

Treatment Measures in Control of Amebiasis. Am. J. Trop. Med. 30:135-138, March 1950.

41 Cram, E. B.: The Effect of Various Treatment Processes on the Survival of Helminth Ova and Protozoan Cysts in Sewage. Sewage Works J. 15:1119-1138, November 1943.


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RECOMMENDATIONS

If the experience gained in World War II is to be utilized in the prevention of amebiasis and other intestinal infections in future military operations, it is necessary to make preparations in advance and to educate each new generation of physicians in the part it must play in a preventive program. The following recommendations are suggested

1. Sanitary discipline of camps, messes, and combat units is a responsibility of the commanding officer and should be given equal importance with other phases of military training. Instruction and practical experience should be given to all personnel from highest to lowest rank. This must include specific directives, and the participation of medical and sanitary officers well trained in the details of preventive measures.

2. Continuous adequate training should be provided for medical, sanitary and laboratory personnel in the accurate diagnosis, treatment, and prevention of amebiasis, considering it as a specific infection of equal importance to bacillary dysentery and other intestinal infections.

3. Efficient portable and emergency water supply equipment and supplies should be devised and prepared which can be furnished to overseas forces and combat units as soon as they are activated.

4. Efficient equipment for mass sanitation, excreta disposal, and fly control should be provided and given high priority in supplies accompanying overseas forces.

5. Special instruction in personal sanitation and continuous supervision of all foodhandlers in military units should be required.

6. On the occurrence of any epidemic of diarrhea in troop units, stools should be examined particularly for E. histolytica as one of the causative agents. If it is found, examination of stools from all members of the unit and treatment of all infected individuals should be carried out. Search should be made for the source of infection and appropriate preventive measures should be instituted.

7. Special stool examinations for E. histolytica on all troops returning from overseas or on discharge from military service should be performed whenever practicable and those found to be infected, should be treated.