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Chapter 24 - Nematode and Cestode Infections

Contents

CHAPTER XXIV

Nematode and Cestode Infections

Clyde Swartzwelder, Ph. D.

With the exception of filarial and hookworm infections, parasitism of United States Army troops by nematodes and cestodes during World War II did not constitute a very important military problem. The total United States Army admissions during the years 1942 through 1945 for infections with selected parasites are shown in table 89. The distribution of hospital and quarters admissions, in 1944, of troops infected with these parasites is presented by area and theater in table 90. Except for trichinosis and tapeworm infections, a large majority of the nematode and cestode infections apparently were acquired overseas.The number of hospital and quarters admissions is indicative of the problem of acute disease.These admissions do not indicate, except indirectly perhaps, the number of troops infected.

The report of Stoll, entitled "This Wormy World," 1 represents a classic in the field of the geography of parasitism. The number of human helminthic infections in millions, calculated by Stoll, is shown in table 91. This table gives ample evidence of the presence of reservoirs of parasitic worms throughout the world which might provide a source of infection and a potential hazard to troops unless adequate protective sanitary measures were employed. Military organizations made numerous surveys of native groups living in the vicinity of troop concentrations; these surveys provide additional evidence of the presence of a source of infection for troops.2

NEMATODE INFECTIONS

Strongyloidiasis

There was a total of 1,242 admissions for infection with Strongyloides stercoralis during the years 1942 through 1945. In 1944, there were 336 recorded admissions for this infection.Of these, 237 represented admissions in overseas theaters. Ninety-nine cases were admitted in the United States during that year. The areas with the largest numbers of reported cases in 1944 were the Central and South Pacific, Southwest Pacific, Latin America,

1 Stoll, N. R.: This wormy world. J. Parasitol. 33: 1-18, February 1947.

2 (1) Hansen, M. F., and Bern, H. A.: A Roundworm Problem in the Philippines. Air Surgeon's Bull. 2: 377, November 1945. (2) Fink, H.: A Helminth Survey From an Autopsy Series on Natives of Okinawa, With Comments on Complications of Ascariasis. Am. J. Trop. Med. 28: 585-588, July 1948. (3) History of Preventive Medicine, Headquarters, U. S. Army Forces, Middle Pacific, December 1941-September 1945, pp. 201-206. [Official record.]


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TABLE 89.-Admissions for selected nematode and cestode infections in the U. S. Army, by diagnosis, area, and year, 1942-45

China-Burma-India, and the Mediterranean (table 90).A single stool examination will fail to diagnose all cases of strongyloidiasis. Many infections require duodenal aspiration for demonstration of diagnostic forms. On a number of occasions, the writer observed cases of strongyloidiasis erroneously


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TABLE 90.-Admissions for selected nematode and cestode infections in the U. S. Army,by diagnosis and area, 1944

diagnosed as hookworm infection in overseas areas. Thus the number of infections acquired no doubt greatly exceeded those, correctly diagnosed and recorded as strongyloidiasis.

Maj. A. A. Liebow, MC, and 1st Lt. C. A. Hannum, SnC,3 reported that infection with S. stercoralis stood next in frequency to hookworm among admissions of troops from the Solomon Islands to the 39th General Hospital for helminthiases. Routine stool examinations which were performed at the hospital between February and December 1943 showed that 7.4 percent of 633 specimens were positive for rhabditiform larvae of S. stercoralis. Denhoff 4 pointed out the striking similarity between the symptoms of patients with strongyloidiasis and those of other troops with anxiety, neurosis. Delay in diagnosis of Strongyloides infections for long periods, without clinical relief, and the lack of a satisfactory treatment contributed to the difficulty in separating complaints from psychoneurosis and those from strongyloidiasis in troops. Denhoff called attention to the fact that duodenal intubation as a diagnostic method for Strongyloides infection lead not been stressed sufficiently. The 8th General Hospital, stationed at New Caledonia in 1944, reported that

3 Liebow, A. A., and Hannum, C. A.: Eosinophilia, Ancylostomiasis and Strongyloidiasis in the South Pacific Area. Yale J. Biol. and Med. 18:381-403, May 1946.

4 Denbolf, E.: The Significance of Eosinophilia in Abdominal Complaints of American Soldiers. New England J. Med. 236: 201-206, February 1947.


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TABLE 91-The calculated number of human helminthic infections, in millions 1

1 Reproduced by permission of Norman R. Stoll, Sc. D.


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TABLE 91-The calculated number of human helminthic infections, in millions- Continued


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hookworm and S. stercoralis were the commonest intestinal parasites encountered. The infections with S. stercoralis were more resistant to treatment and appeared to be more clinically significant than the hookworm infections.5 A prevalence of strongyloidiasis of 12 percent was reported in 150 Puerto Rican enlisted men at Fort Brooke, P. R.6 One infection with Strongyloides fulleborni, normally a parasite of monkeys, was recorded. 7 The patient had kept a pet monkey while stationed on the island of Leyte in the Philippines.

The following information supplied by Dr. C. A. Jones, chief of the medical service of the Veterans' Administration Hospital, New Orleans, La., provides excellent information on the problem of strongyloidiasis in veterans of World War I and World War II. Between 4 May 1946 and 11 October 1950, 21,784 patients were admitted to the hospital. The diagnosis of strongyloidiasis was established in 123 of these patients-approximately 0.6 percent of the total admissions. Forty-two of these patients were veterans of World War I. Of this group, 14 served in areas outside the United States. Thirteen had service within the continental limits of the United States. In 15 cases, data on foreign service were not recorded. The available records indicate that all except one of these patients had no military duty outside the continental limits of the United States for approximately 30 years. The World War I group of patients probably acquired their infections in areas around their homes. Most of these World War I veterans were farmers or had other occupations which brought them in close contact with the ground. The homes of 35 of these World War I veterans were in rural Louisiana, Mississippi, or Arizona. Seven lived in New Orleans. Each of this older group of patients had received an average of 66 days of hospital care. This prolonged period of hospitalization resulted from repeated admissions to the hospital and complicating or accompanying chronic degenerative diseases. The relative proportion of veterans of World War I and of World War II in the series of 123 cases was approximately the same as the ratio of their admission to the hospital.8

There were 81 patients whose service occurred during World War II. One of these had service in both the First and Second World Wars. In contrast to the patients of World War I, at least 46 had duty outside the continental limits of the United States. Twenty-five of this group served in England, France, Italy, North Africa, or in the Middle East. The remainder had duty in the Pacific. Twenty-three had service exclusively within the continental limits of the United States. In 12 cases, the precise location of military duty other than the United States was not stated. The World War II veteran group included farmers, laborers, truck drivers, and skilled mechanics. The majority of these veterans lived in rural areas of Louisiana, Mississippi, and Texas. Thirteen came from larger communities such as New Orleans,

5 Annual Report of the Activities of the 8th General Hospital, New Caledonia, for the year ending 31 December 1944.

6 History of Medical Department Activities, Antilles Department, Preventive Medicine, p. 67.[Official record.]

7 Wallace, F. G., Mooney, R. D., and Sanders, A.: Strongyloides Fiilleborni Infection in Man. Am. J. Trop. Med. 28: 299-302, March 1948.

8(1) Personal communication to author.(2) Jones, C. A.: Clinical Studies in Human Strongyloidiasis; Semeiology. Gastroenterology 16: 743-756, December 1950.


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Birmingham, Ala., and Houston, Tex. The epidemiologic data indicate that these patients, with few exceptions, live in areas where strongyloidiasis is endemic. In the patients who served in World War II, exposure to polluted soil in endemic areas in the United States is probable. However, over half of these veterans served outside the limits of the United States in areas where strongyloidiasis is also endemic and prevalent. The hazard of infection was probably greater under overseas combat conditions than in these men's civilian occupations or around their homes.

Of the 123 patients in whom a diagnosis of strongyloidiasis was established, approximately 90 percent had gastrointestinal symptoms of mild or severe nature. These symptoms were mainly those of abdominal pain, diar rhea, and allergic manifestations such as urticaria and asthma. Many have had repeated recrudescences of symptoms requiring repeated hospitalization; this has already resulted in an average period of hospitalization of approximately 45 days for each of these World War II veterans. Many of this latter group had no other disease to account for their illness, in contrast to veterans of World War I, many of whom had other chronic diseases to prolong their hospital stay. Data on the first 100 patients with the diagnosis of strongyloidiasis have been reported by Dr. Jones in Gastroenterology.

It is interesting to note that Hall 9 reported in 1918 that Dr. C. W. Stiles recommended during World War I that soldiers infected with S. stercoralis should be discharged from the service. The reason for this recommendation was that no satisfactory treatment for this condition was known.

It is the opinion of the writer that strongyloidiasis constitutes an important postwar problem among veterans. In many cases, the disease is difficult to diagnose, with the result that infection may be overlooked for long periods. The duration of some infections apparently may be 10 or more years. The natural reduction or loss of infection without treatment appears to be less marked in strongyloidiasis than in many other intestinal helminthiases. Treatment of strongyloidiasis is not satisfactory, although clinical relief may be afforded by repeated courses of gentian violet. The search for an effective therapeutic drug merits investigation and support in order to remove infections acquired during military service. Most of the measures designed to prevent hookworm infection in troops would also serve to prevent strongyloidiasis. The initial mode of infection, that is, penetration of the skin by larvae, is similar in both infections.

Ascariasis and Trichuriasis

Maj. C. A. Kofoid, SnC, 2d Lt. S. I. Kornhauser, SnC, and 2d Lt. J. T. Plate, SnC, recorded a prevalence of 1 percent of ascariasis in overseas troops and a 0.3 percent prevalence in home-service troops in World War 1. They also reported that there was a definite indication of acquisition of Trichuris

9 Hall, M. C.: Parasites in War Time. Scient. Monthly 6:106-115, February 1918.


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trichiura, the whipworm, in troops with overseas service during the First World War.The study involved 1,200 overseas and 300 home-service troops of the United States Army.The prevalence of whipworm infection was 6 percent in the overseas troops and 2 percent in the home-service group. This threefold increase was all the more significant if allowance was made for the fact that 5 of the 6 infections in home-service troops were in recent immigrants from Italy and Russia. If these infections were deducted, the prevalence in the remaining home-service troops was 0.3 percent.10

In World War II, there were 5,031 admissions of United States Army troops for ascariasis between 1942 and 1945. The admissions for infection with Ascaris lumbricoides in overseas theaters totaled 3,630. The remainder, 1,401, represents admissions in the continental United States. In 1944, the largest numbers of admissions for ascariasis occurred in the Mediterranean and European Theaters of Operations. No figures are available for hospital admissions for trichuriasis. Usually only heavy infections with T. trichiura produce clinical manifestations. Light infections, which ordinarily are subclinical, are not treated for lack of a completely satisfactory therapeutic agent.A few reports of experiences with these two intestinal nematodes in troops follow.

Capt. D. R. Lincicome, SnC, and 1st Lt. John R. Shaver, SnC, reported a 34.4 percent prevalence of ascariasis in the 13th Engineer Battalion, 7th Infantry Division, which had been in combat on Leyte.11 An infantry battalion stationed near Manila, P. I., were examined by personnel of the 26th Medical Laboratory, who found 18 percent of the troops infected with A. lumbricoides and 10.7 percent infected with T. trichiura.12 Incidentally, a prevalence of 83 percent infected with A. lumbricoides was recorded in a group of Philippine civilians who lived adjacent to troops.13 May 14 surveyed 400 American Soldiers interned by the Japanese and found that 35 percent had ascariasis and 40 percent had trichuriasis. A. lumbricoides was second in prevalence among parasitic helminths in continental soldiers stationed in the Canal Zone. The infection rate per 1,000 per annum from 1940 to 1945 was 3.96.15 Intestinal parasitism was found in about 80 percent of 150 Puerto Rican soldiers examined at Fort Brooke. The prevalence of T. trichiura, the whipworm, was 55 percent. 16 Other surveys of Puerto Rican troops stationed in the United States revealed prevalence of 53 and 72 percent infected with T. trichiura despite postinduc-

10 (1) Kofoid, C. A., Kornhauser, S. I., and Plate, J. T.: Intestinal Parasites in Overseas and Home Service Troops of the U. S. Army. J. A. M. A. 72:1721, June 1919. (2) The Medical Department of the United States Army in the World War.Communicable and Other Diseases.Washington: U. S. Government Printing Office, 1928, vol. IX, pp. 529-549.

11 Medical Bulletin No. 19, Headquarters, Army Service Command 1, Office of the Surgeon, Okinawa, 17 Sept. 1945.

12 Essential Technical Medical Data, Headquarters, U. S. Army Forces, Pacific, October 1945, p. 35.

13 Semimonthly Report of Activities of the 19th Medical Service Detachment (General Laboratory), U. S. Army Services of Supply, for the First Half of March 1945, to the Chief Surgeon, Headquarters, U. S. Army Services of Supply, Southwest Pacific, 17 Mar. 1945.

14 May, E. L.: Parasitologic Study of Four Hundred Soldiers Interned by the Japanese. Am. J. Trop. Med. 27: 129-130, March 1947.

15 Professional History of Internal Medicine in World War II, 1 January 1940 to 1 October 1945, the Panama Canal Department, vol. II, p. 252.[Official record.]

16 See footnote 6, p. 508.


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tion treatment.17 A routine stool survey of 1,456 insular troops who were admitted to hospitals in the Canal Zone revealed that 76 percent were positive for ova of T. trichiura. The whipworm rate in insular troops in the Panama Canal Department per 1,000 per annum as determined by stool examination during hospitalization (1943-45) was 21.31.18 The 105th General Hospital, which was located in the -Southwest Pacific, received a large number of patients who were infected with T. trichiura. The infections were asymptomatic, and no treatment was administered. 19

In general, infections with A. lumbricoides, the large intestinal roundworm, and with T. trichiura, the whipworm, were of minor medical significance in United States Army troops during World War II. No deaths in troops were caused by either of these parasites. About 5,000 admissions for ascariasis were recorded. Effective anthelmintics were available for therapy of cases of ascariasis. The treatment is of short duration and does not require prolonged hospitalization. Trichuriasis was apparently prevalent in many overseas theaters. High prevalences were recorded in numerous surveys. Most cases of whipworm infection have light worm burdens which represent subclinical infections.Some of the 2,275 admissions listed under "Nematode infection, other" (table 89) possibly include clinical cases of trichuriasis. Since an effective anthelmintic for the treatment of whipworm infections is lacking, search for a satisfactory drug for use in clinical infections should be initiated and supported.

In countries where human feces are commonly used as fertilizer, troops generally were prohibited from serving and eating vegetables raw. The regulation probably prevented numerous cases of ascariasis. Embryonated eggs in feces-polluted soil frequently provide the source of infection.Troops often are, of necessity, in contact with soil from which their hands may easily be contaminated. Ingestion of these eggs will produce infection. Personal hygiene, therefore, is very important in the prevention of ascariasis. Proper disposal of excreta is necessary to prevent spread of the infection.

Enterobiasis

The total number of admissions for Enterobius vermicularis, the pinworm, is recorded as 1,272 (table 89). Of these, 889 occurred in overseas troops. The symptoms of many pinworm infections probably were not severe enough to induce men to seek medical treatment. Anal-swab techniques were not universally employed in military establishments for the diagnosis of Enterobius infections. Since stool examination is notoriously inefficient for the detection

17 (1) Report of Disinfestation Program in 762d and 891st Antiaircraft Gun Battalion, by Lt. Col. G. H. Houck, MC, Capt. P. L. Burlingame, SnC, Capt. M. S. Watts, MC, and 1st Lt. G. T. Marconis, MC, Fourth Antiaircraft Command, Post Office Box 3552, San Francisco 19, Calif., 5 Aug. 1945. (2) Letter, Lt. Col. G. H. Houck, MC, Army Air Forces Regional and Convalescent Hospital, Office of Chief of Medical Service, Santa Ana Army Air Base, Calif., to the Surgeon, Headquarters, Fourth Air Force, San Francisco, Calif., 22 June 1945.

18 See footnote 15, p. 510.

19 Annual Report of 105th General Hospital, Southwest Pacific, 29 Jan. 1944.


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of pinworm infections, the statistics probably do not reflect the degree of parasitism even in clinical cases of enterobiasis in troops. The small number of admissions recorded suggests that Enterobius infection was not a serious problem. Pinworm infection reaches high incidence under institutional conditions. Troops living in barracks or otherwise housed in large groups provide similar conditions which might predispose to mass infection with E. vermicularis.Viable pinworm ova may occur in household dust, bedclothing, toilet fixtures, and innumerable other objects indoors. Rigid personal. hygienic measures and cleanliness of troop quarters are necessary to minimize and suppress this infection.

Trichinosis

There were only 285 hospital and quarters admissions for trichinosis in the United States Army recorded from 1942 through 1945 (table 89). About three-fourths (208) of these admissions occurred in the United States. One death from trichinosis was recorded in 1944.Additional cases were recorded in May 1941 by Maj. Alexander A. Marble, MC, Capt. Allen P. Skoog, MC, and 1st Lt. Donald J. Bucholz, MC.20 Thirteen soldiers in L Company, 104th Infantry Regiment, 26th Infantry Division, Camp Edwards, Mass., were admitted to the station hospital with clinical trichinosis. Based upon the presence of eosinophilia, it was estimated that from one-third to one-half of Company L (142 troops) probably had asymptomatic trichinosis.

The low incidence of trichinosis in United States Army troops suggests that pork and pork products generally were cooked thoroughly before being served in military installations.

Trichinosis was more of a problem in German prisoners of war than in United States Army troops. Several outbreaks occurred among interned prisoners. Many German prisoners of war preferred and were accustomed to eating meat raw. The outbreaks of trichinosis among these prisoners were due primarily to this habit and to the failure of prisoner-of-war cooks to comply with clear and precise instructions to cook all pork and pork products thoroughly before serving to their fellow prisoners. To obtain better compliance with orders for the proper preparation of meat to prevent trichinosis, closer supervision of mess personnel and oral as well as written instruction of all prisoners of war would be necessary. Section VII, Army Services Forces Circular No. 160, 4 May 1945, specifically prohibited permitting German prisoners of war to consume raw pork.

An outbreak of trichinosis occurred at Camp Atterbury, Ind., in December 1945. One hundred and three prisoners of war with trichinosis were admitted to Wakeman General Hospital. The clinical diagnosis was adequately substantiated by laboratory studies. Because of lack of hospital space, 77 others with symptoms similar to those exhibited by patients sent to the hospital

20 Marble, A., Skoog, A. P., and Bucholz, D. J.: Trichinosis: Report of an Outbreak at Camp Edwards, Massachusetts. Mil. Surgeon 90: 636-643, June 1942.


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were admitted to isolation barracks. In addition there were 409 patients with similar but milder symptoms who were kept in their quarters. There were no cases of trichinosis reported in American personnel at the camp. Epidemiologic evidence indicated that canned bacon and pork which were consumed without cooking caused the infections. Eleven prisoners of war from the prisoner-of-war camp at Austin, Ind., who had trichinosis were also sent to Wakeman General Hospital in December 1945. 21

Eighty-three German prisoners of war with clinical trichinosis were admitted to an Army Air Force regional station hospital in the United States in December 1945.22 Uncooked sausage presumably provided the source of infection. An outbreak of trichinosis also occurred at Fort Custer, Mich.23 It resulted in the hospitalization of 256 German prisoners of war. Raw pork sausage which lead been made into sandwich spread and inadequately cooked meat loaf, prepared contrary to published orders, presumably were the sources of infection. A board of officers recommended that:

1. All meals should be inspected by American personnel at the time the meal is being served.

2. All mess personnel, American and German, should read, in the presence of the commanding officer of the respective company, all instructions relative to preparation and serving of food to prisoners of war.

3. All members of the respective mess details should sign the above instructions after reading them.

4. Copies of these instructions should be posted in a conspicuous place in each messhall.

CESTODE INFECTIONS

There were 2,036 admissions for cestode infections recorded during the period 1942-45. Of this total, 1,349 admissions were in the United States. Twenty-two admissions for Echinococcus infection occurred during the period. Cysticercosis was reported in one patient during 1944 and 1945.There were 2,013 other cases of cestode infection. Most of these were probably due to Taenia saginata, the beef tapeworm.Had any cases of cysticercosis occurred in 1942 and 1943, which seems relatively unlikely, they would have been included among 932 of the above 2,013 cases of cestode infection (footnote 5 of table 89).

21 (1) Letter, Col. W. O. H. Prosser, MC, Post Surgeon, Camp Atterbury, Ind., to the Commanding General, Fifth Service Command, Army Service Forces, Fort Hayes, Ohio, 29 Dec. 1945, subject: Investigation of Outbreak of Trichinosis Among German Prisoners of war. (2) Davis, W. A., and Cleland, R. R.: Trichinosis in Prisoners of War. Bull. U. S. Army M. Dept. 7: 973-976, November 1947.

22 Hathaway, F. H., and Blaney, L.: Trichinosis; Report of an Epidemic. Ann. Int. Med. 26: 250-262, February 1947.

23 (1) Annual Report, Surgeon, Sixth Service Command, Calendar year 1945, to the Commanding General, Army Service Forces, 27 Feb. 1946. (2) Report of Proceedings of Board of Officers, Army Service Forces, Sixth Service Command, 1611th Service Command Unit, Prisoner of War Camp, Fort Custer, Mich., 17 Mar. 1945. (3) Oppenheim, T. M., Whims, C. B., and Frisch, A. W.: Clinical and Laboratory Observations on 256 Cases of Trichinosis.Bull. U. S. Army M. Dept. 6: 581-593, November 1946.


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Echinococcus Infection (Hydatid Disease)

Military personnel were no doubt exposed to Echinococcus infection in endemic areas such as New Zealand, Australia, the Mediterranean littoral, and Iceland.Although 15 of the 22 cases of echinococciasis in United States Army troops were admitted to hospitals in the United States, their origin may well have been in overseas theaters either prior to or during World War II. The disease is endemic in the United States, but it is also rare in occurrence.24 The incubation period in some cases of hydatid disease may be many years in duration. One death from Echinococcus infection occurred in 1944. In 1947, Mathieson 25 reported a case of hydatid disease of the lung in a United States Army veteran of World War II. According to Magath,26 the patient lead been in Casablanca, French Morocco, 4 months, another 8 months elsewhere in North Africa, and 16 months in and about Naples and elsewhere in southern Italy. The only contact which the patient had with dogs was in Italy, where the soldier's infection was most likely acquired.

Occasionally troops kept dogs as pets and unit mascots in overseas areas where hydatid disease was endemic.Trained dogs were also used by military services.Dogs constitute the chief source of human infection with Echinococcus granulosus. Since the parasite may, in many cases, require years of development in man before clinical manifestations result, it is possible that this disease may occasionally be detected in the future in veterans. If troops were prohibited from keeping dogs as pets, the hazard of infection might be reduced. However, complete enforcement of such a regulation is difficult to attain.

Cysticercosis

The results of a recent statistical investigation of individual records of cysticercosis indicated that there was actually only one case of this disease. The admission occurred in the Mediterranean theater in 1945. Cysticercosis is a relatively rare infection with the larval stage of Taenia solium.

Man is the only host of the pork tapeworm, T. solium. Since infection with Cysticercus cellulosae ordinarily originates from ingestion of T. solium eggs (except in cases of internal autoinfection), contamination of food or drink with human excrement must occur for cysticercosis to be transmitted. Proper disposal of excreta and rigid personal hygiene are necessary to avoid infection. In areas where T. solium is heavily endemic, care should be taken to avoid or minimize transmission of the infection from the native population to troops.

24 Swartzwelder, J. C.: Echinococcus Infection (Hydatid Disease) in Louisiana.New Orleans M. & S. J. 99:617-619, June 1947.

25 Mathieson, D. R.: The Present Status of Tropical and Exotic Diseases Among Servicemen. Journal Lancet 67: 37-40, January 1947.

26 Personal communication to author from T. B. Magath, Mayo Clinic. Rochester, Minn., 18 Aug. 1950.


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Other Cestode Infections

The number of other cestode infections was approximately 2,000. T. saginata presumably was the commonest tapeworm in these cases. Two-thirds of these cases were admitted to hospitals in the United States.In 1944, the European and Mediterranean theaters and the Central and South Pacific contributed most of the overseas admissions for cestode infections. Taenia infections are acquired from eating inadequately cooked beef or pork, depending upon the species of tapeworm involved. The necessity of cooking these meats and their products adequately is obvious.Many of the T. saginata infections in troops in the United States may have been acquired by eating in civilian restaurants or in homes as well as in Army installations.

INTRODUCTION OF INFECTIONS INTO THE UNITED STATES

A survey for intestinal helminths in 4,000 soldiers processed for separation at Fort McPherson, Ga., revealed that the prevalence of A. lumbricoides, T. trichiura, S. stercoralis, E. vermicularis, and Hymenolepis nana infection was less than 1 percent for each. About two-thirds of the group had overseas service, and the remainder had service only in the continental United States. The prevalence indicated a low acquisition rate of these intestinal helminths.27 Mackie and Sonnenberg 28 found a low prevalence of infection with most helminths in 484 veterans studied. The number of infections for each parasite was A. lumbricoides, 7; S. stercoralis, 10; T. trichiura, 22; and Taenia species, 1.

Wright and McCoy predicted that the return of infected troops would make little difference in the public health status of these infections in the United States .29 The relatively small number of hospital admissions of United States Army troops from 1942 through 1945 (table 89) and the apparently low prevalence of infection found in separatees with overseas service and in veterans, if representative, support the views of Wright and McCoy that these helminth cases in returned servicemen offer no basis for exceptional concern from a public health point of view. The helmintbs considered in this section are already endemic in this country. The slight increment of infection contributed by returned troops probably is extremely small in comparison with the number of infections already present in the civilian population. This does not necessarily apply to Ancylostoma duodenale, the Old-World hookworm.

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

28 Mackie, T. T., and Sonnenberg, B.: Tropical Disease Problems Among Veterans of world war II. Am. J. Trop. Med. 29: 443-451, July 1949.

29 (1) Wright, W.H.: Present and Post-War Health Problems in Connection With Parasitic Diseases. Science 99:207-213, 17 Mar. 1944. (2) McCoy, O. R.: Public Health Implications of Tropical and Imported Diseases; Imported Malaria.Am. J. Pub. Health 34: 15-19, January 1944. (3) McCoy, O. R.: Precautions by the Army to Prevent the Introduction of Tropical Diseases. Am. J. Trop. Med. 26: 351-355, May 1946.


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SUMMARY

Parasitism of United States Army troops by nematodes and cestodes, with the exception of filarial and hookworm infections, did not constitute a serious military problem during World War II. There is abundant evidence of a high incidence of helminthiases in native inhabitants of certain overseas areas. The practice of basic sanitary preventive measures must have contributed to the over-all low incidence of infection in troops stationed in these areas.

There were 1,243 recorded admissions for strongyloidiasis from 1942 through 1945. About two-thirds of these occurred in overseas theaters. Most of the diagnoses were based upon stool examination which is of limited value as a diagnostic measure for this infection. The similarity between the symptoms of patients with strongyloidiasis and those of troops with anxiety neurosis created a diagnostic problem. Of the common nematode and cestode infections, strongyloidiasis possibly represents the most potential postwar problem among veterans. Measures designed to prevent hookworm infections no doubt were to a great extent operative against strongyloidiasis.

Admissions for ascariasis during this 4-year period numbered 5,031.Of this total, 3,630 were in overseas theaters. In view of the high incidence of ascariasis in native inhabitants of many overseas areas, appropriate preventive measures must be taken to minimize transmission of this infection to troops. Whipworm infection, caused by T. trichiura, apparently was frequent in troops in some overseas areas. The incidence of T. trichiura was high in native troops from Puerto Rico and the Canal Zone. Whipworm infections usually were subclinical.

The small number of admissions for enterobiasis, 1,272, suggests that this infection did not constitute an important problem in troops during the war. It is known that pinworm infection attains high incidence under institutional conditions. Troops are often housed in large groups. This enhances the opportunity for dissemination of this parasite. Therefore, rigid personal hygienic measures and cleanliness of troop quarters are mandatory if the spread of this infection is to be prevented.

About three-fourths (208) of all hospital admissions for trichinosis (285) in United States Army troops were in the United States. One death from trichinosis occurred in 1944. There were a few outbreaks of trichinosis in German prisoner-of-war camps. These resulted from the habit of some prisoners of eating pork raw and from the failure of prisoner-of-war cooks to comply with instructions to cook all pork and pork products thoroughly. Closer supervision of prisoner-of-war mess personnel and instruction of all prisoners of war would have secured better compliance with orders for the proper preparation of pork to prevent trichinosis. Trichinosis was more of a problem in these prisoners of war than in United States Army troops.

There were over 2,000 admissions for cestode infections in United States Army troops. The majority occurred in the United States. Echinococcus or


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hydatid infection was recorded 22 times. One death was caused by echinococciasis. The long incubation period of hydatid disease may result in the clinical appearance of this infection in veterans in future years. The danger of acquiring this infection from dogs should be emphasized to troops.

At least one case of cysticercosis occurred in troops. In areas where T. solium, the pork tapeworm, is heavily endemic, care should be taken to avoid transmission of infection from natives to troops through fecal contamination of food and drink.

Troops should be instructed to eat only adequately cooked beef at Army installations or at civilian establishments to prevent T. saginata infection. The need for such instruction is indicated by the occurrence of approximately 2,000 admissions for cestode infections.

The number of infections with these helmintlhs in troops returned from overseas is small in comparison with the number already present in the civilian population of the United States where the infections are endemic.The return of the troops with these helminthiases probably will not make any significant difference in the public health status of the infections in this country.