Ernest Carroll Faust

Parasitological surveys in Cali, Departamento del Valle, Colombia VI. Strongyloidiasis in Barrio Siloé, Cali, Colombia

Abstract 1. 1) In connexion with a continuing parasitological survey of a representative sampling of the population in ward Siloe, Cali, Colombia, conducted as part of an epidemiological study of this economically poor community, a special segment of the programme has been concerned with Strongyloides stercoralis infection. This investigation included 92 families comprising 982 persons. Freshly-passed faecal specimens were examined macroscopically and microscopically for intestinal parasites, employing unstained and iodine-stained direct faecal films supplemented by zinc sulphate concentration preparations. 2. 2) A total of 2974 stools were examined from November, 1956, through April, 1959. One hundred and thirty-seven (14 per cent.) of the 982 individuals were found positive for Strongyloides. One hundred and six were first diagnosed from the first specimen submitted, 20 were first diagnosed from the second specimen, seven from the third sample, and four from the fourth. Subsequent samples provided no additional first positives. 3. 3) The zinc sulphate centrifugal floation technique proved to be 50 per cent. more efficient than the double cover-glass direct films in discovering Strongyloides larvae. 4. 4) One or more persons in each of 62 of the 92 families were found to be infected, by the techniques employed. The number of positive persons per family varied from one to nine. 5. 5) Appreciable infection (4.8 per cent.) occurred before 5 years of age, after which time the incidence rate rose rapidly during the next quinquennium, maintained this level for three decades, rose again in the fourth decade, remained high in the males and rapidly declined in the females. The incidence per cent. was consistently higher in the males than in the females after the first 5-year period. 6. 6) Environmental conditions and low-grade personal hygiene are conducive to exposure to infective-stage Strongyloides on the moist dirt floors of the houses of the community. Autoinfection may play a significant role in maintaining the infection once it has become established. 7. 7) There is no evidence that strongyloidiasis in ward Siloe is a severe debilitating disease; rather it appears to be a chronic parasitosis which is fairly well tolerated.

INVESTIGATIONS IN PANAMA DURING THE SUMMER OF 1930

The material obtained from these investigations has indicated to the writer that the area studied offers extremely valuable opportunities for helminthological and protozoological work. The data obtained will serve as the basis for several important papers which will be published in the near future.

Influence of Certain Foodstuffs on Lesions of Endamoeba histolytica Infection.

It has been shown 1 , 2 that raw liver and liver extract are distinctly beneficial to dogs suffering from acute amebic enteritis. On the other hand, ventriculin was found to be consistently harmful to the host. Furthermore, one of us (E.C.F.) discovered several years ago that dogs which were resistant to amebic infection on a balanced diet, could usually be infected when they were fed canned salmon. Our present inquiry is directed to the nature of the complex relations produced by these 3 foodstuffs on the wall of the large intestine, when the host has amebic enteritis. This report outlines our findings up to the present time and offers no explanations for the results obtained. Twenty-six healthy young dogs have been used in the study. None were naturally infected with amebae. All were inoculated intracecally 3 with the same human strain of Endamoeba histolytica. All were suffering from acute amebiasis of a few days standing when the tests were made. Fresh pigs liver, ventriculin (furnished by Parke, Davis and Co.) and commercial canned pink salmon (grade B) were the foodstuffs employed. Only one animal died; the remainder were sacrificed. In the liver series 150 gm. of unchopped raw liver were fed to one animal daily. Clinical improvement began about the ninth day, and on sacrifice 13 days later only a few small shallow amebic lesions were found in the cecum and rectum. In contrast, when only 60 gm. of finely chopped liver in liver juice were fed to the host, improvement was noted on the fifth day, and on sacrifice 3 days later only a few shallow lesions were seen in the rectum. In 4 animals both the liquid and solid fractions of finely chopped liver were introduced into the large intestine.

Differences in culturability, infectivity and pathogenicity of human strains of Endamoeba histolytica.

Summary Investigations have been undertaken in an attempt to reconcile some of the many conflicting opinions which have developed regarding the pathogenicity of E. histolytica. The problem undertaken and presented in this communication concerns the culturability, infectivity and pathogenicity of 18 different “strains” of the organism, obtained from persons in New Orleans. The hosts varied in age from 2 to 59 years. All but one were hospital or clinic patients, the majority of whom complained of some type of colitis. In 11 cases stools containing cysts or trophozoites were obtained; in 5 cases proctoscopic material was utilized, in one case a purgative specimen was secured and in one instance the inoculum consisted of material previously cultured in a hospital laboratory. For culture work a solid egg-slant base was employed, with a liquid overlay of physiological salt solution containing 0.5% crude liver extract and special rice starch. Cysts were concentrated and washed before seeding the cultures; trophozoites in fecal or mucous samples were placed directly in the culture tubes. Kittens served as the principal animals to test infectivity and pathogenicity of each strain. A minimum of 5 kittens was employed. Pathogenicity was first estimated on the basis of clinical evidence, then carefully studied at autopsy. The length of intestine from the posterior level of the ileum through the rectum was considered as 8 separate segments and amebic invasion of the bowel separately assessed for each segment. Four degrees of pathogenicity were recognized and were designated as +, ++, +++ and ++++. Based on these symbols a pathogenic index was developed to afford comparisons between different series. Of the 18 “strains” 6 proved difficult to grow in culture; 4 of these were unsatisfactory for animal work and were discarded.

Immunologic Studies on Experimental Trypanosoma cruzi Infections I. Lysins in Blood of Infected Rats.

Summary Blood serum of animals infected with Trypanosoma cruzi caused Iysis of this organism from cultures in less than 2 hr and, when diluted 1: 5, in 3 to 5 hr. When the animals were blocked as well, the time required for lysis was increased and the Iytic titer of the serum was reduced.

Infection Experiments in Man and Other Mammalian Hosts with Sparganum Stage of Oriental Diphyllobothrids

The Sparganum larva of a diphyllobothrid (psaudophyllidean) cestode was first recovered from man in 1882 by Patrick Manson, who obtained a dozen of these ligulate worms from the perirenal fat of an Amoyese. The same year Scheube obtained similar material from a Japanese subject. Following these early cases numerous additional human infections were described from Japan and French Indo-China, the latter being almost if not entirely from the orbit. A few human cases have also been reported from Australia. These larvae have been consistently designated as “Sparganum mansoni”, after their discoverer. Meanwhile larvae indistinguishable from those recovered from the human host have been obtained from numerous vertebrates in the Orient, including frogs, snakes, birds and mammals. These, too, have commonly been referred to as “Sparganum mansoni”, although experimental feedings to dogs and cats of the larvae from human cases in Japan (Okumuras 1 material) have shown that the adult worms belong to 2 previously described species, Diphyllobothrium decipiens and D. cordatum, while similar experiments in French Indo-China (Joyeux and Houdemer 2 ) have produced adults of another species which these investigators have described as “Diphyllobothrium mansoni”. During a period of more than 8 years the writer has collected adult diphyllobothrids from naturally infected dogs and cats and their wild relatives in China and has had placed in his hands for study a complete worm of the generic group from the intestine of a native Chinese in Shanghai. These Chinese worms have been diagnosed as belonging to the following species: Diphyllobothrium cordatum (Leuckart, 1863), Stiles and Hassall. 1926, (dog, Peking and Amoy); D. mansoni (Cobbold, 1883), Joyeux, 1927, (cat, Canton, Foochow, Peking); D. decipiens (Diesing, 1850), Chandler, 1925, (cat, wild-cat, leopard, Peking); D. ranarum (Gastaldi, 1854), Meggitt.

Habitat of Giardia in the Intestine.

Authorities on intestinal protozoa (Hegner, 1 Wenyon, 2 Lynch 3 ) state that Giardia lives in the upper part of the small intestine, mainly in the duodenum rather than in the cecum which is a common habitat for Trichomonas and Chilomastix. Hegner 4 has described Giardia canis as the species present in the dog, but has not recorded the level of the intestine in which this organism has been found. In connection with our Tulane Strain A of Endamoeba histolytica in dogs we have encountered Giardia canis as a contamination. In maintaining the ameba in vivo by continuously subinoculating one dog from another per rectum (Faust), we have had an opportunity to study in life and at autopsy dogs which have received the Giardia as an experimental infection. These observations we have compared with data obtained from naturally infected dogs. In the majority of our cases harboring a natural Giardia infection the primary seat of the organism is in the cecum and appendix; frequently it is also in the colon and the rectum; occasionally it is found in the distal 10 cm. of the ileum; it has never been seen by us in the higher levels of the small intestine. In experimental infections of our dogs, previously found by repeated fecal examination to be negative for intestinal protozoa, we have encountered a somewhat different situation. The active Giardia trophozoites were introduced by rectal tube into the upper levels of the large bowel and usually expelled there. In some cases the tube passed the ileo-cecal valve and the inoculum was discharged anterior to the valve. In nearly 50 cases available for analysis an infection of 100% has been obtained. In most of the animals the active Giardias were consistently present in the feces from the second day; in 4 instances they were recorded as early as 24 hours after inoculation.

Experimental Acute Amebic Colitis in Dogs.

Summary 1. By utilizing a technic whereby muco-sanguinous exudate f rom active cases of amebic colitis in dogs is injected per anum into the distal portion of the ileum, infection corresponding to spontaneous amebiasis in this host has been produced in 13 out of 14 dogs (93%), ranging in age from 2 months to 4 years. 2. The incubation period, as determined by the presence of active Endanzoeba histolytica in mucus withdrawn directly from the cecum, has ranged from one to 23 days, with the largest number of findings on the second day. 3. Acute cases, probably complicated by bacteremia, terminate with death in about 2 weeks. Chronic cases and one spontaneous recovery have also been observed. Carrier cases, with the passing of cysts in the stools, apparently do not develop in dogs. 4. The cecum is the primary seat of infection with E. histolytica in the dog. 5. The dog apparently receives its amebic infection from man but due to the failure to produce cysts the infection apparently cannot be transferred in nature from dog to dog or from dog to man.

A Method for obtaining a Pure Culture of Balantidium coli.

Balantidium coli, the ciliate of the large bowel of the pig, and not infrequently reported from man, the monkey and the guinea pig, has been grown in vitro by Walker, 1 Barrett and Yarbrough 2 and Rees. 3 The latter investigator was able to isolate single individuals and start a pure line of the organism obtained from the guinea pig. In all of these attempts, however, the medium was contaminated by various fecal bacteria and no efforts appear to have been made to develop pure cultures, although the need for such a procedure is evident. Opportunity to attempt the sterilizing of balantidia against fecal bacteria was presented to the writer during the summer of 1929, when all of 12 individuals of Macacus rhesus, which had been under observation by Dr. C. C. Bass for a non-protozoan infection, were found to be passing cysts and trophozoites of Balantidium coli in their stools. Rectal specimens from those individuals which gave the richest yields of trophozoites were washed and concentrated in a modified Ringers fluid and the active organisms freed of fecal debris and gross bacterial contamination. Preliminary tests were then made with several bactericidal agents in various dilutions to determine if any could be found which were lethal to the bacteria without injuring the active balantidia. The most promising of these were acriviolet and neutral acriflavine. The washed trophozoites were placed in the following dilutions of each of these drugs and the organisms examined after 5 minutes, 10 minutes, 30 minutes and 60 minutes respectively: 1/1,000; 1/2,000; 1/4,000; 1/8,000; 1/16,000; 1/32,000; 1/64,000; and 1/128,000. In both series the dilutions of 1/8,000 or less, even for as short a period as 10 minutes were toxic to the trophozoites.

Parasiticidal Properties of the Proteolytic Enzyme Ficin.

Summary The unpreserved, refrigerated crude latex was consistently the most efficient parasiticide tested, the preserved latex somewhat less effective. A 10% solution of the freshly opened crystoid compared favorably with the refrigerated latex but exposure to air rapidly diminished its potency. The amorphous ficin, while relatively stable, proved to be only about half as efficient as the fresh crystoid. The most specific action of these products occurred on whipworms, provided the large bowel was previously free of feces. The effect on hookworms was almost uniformly less satisfactory. Considerable amebostatic and, at times, amebicidal action was demonstrated.