Iodamoeba Research Articles

The Role of Housing Type and Drinking Water in Prevalence of Intestinal Parasites Among Pupils of A Number of Primary Schools in Rural Area of Al-Taamem Province-Iraq

The results of examining 806 pupils of 19 primary schools in rural regions of Al-Taamem province living in houses of variable buildings and drinking water from different sources revealed their infection with the following intestinal parasites: Protozoa ; Giardia lamblia 9.90% ; Entamoeba coli 5.30% ; E. histolytica 4.73% ; Iodamoeba butschlii 1.32% ; Endolimax nana 0.88% ; Chilomastix mesnili 0.50% and Trichomonas hominis 0.19% . Helminths ; Hymenolepis nana 4.03% ; Enterobius vermicularis 2.10% ; Ascaris lumbricoides 0.63% and Trichuris trichiura 0.38% with a total percent of infection 29.95%. The highest infection rate appeared in pupils inhabited muddy houses which differs significantly (P = 0.05) from all other types of houses and those using water from wells from other sources of water.

Disparities in parasitic infections, perceived ill health and access to health care among poorer and less poor schoolchildren of rural Côte d'Ivoire

Differences in the state of health between rural and urban populations living in Africa have been described, yet only few studies analysed inequities within poor rural communities. We investigated disparities in parasitic infections, perceived ill health and access to formal health services among more than 4000 schoolchildren from 57 primary schools in a rural area of western Côte d'Ivoire, as measured by their socioeconomic status. In a first step, we carried out a cross-sectional parasitological survey. Stool specimens and finger prick blood samples were collected and processed with standardized, quality-controlled methods, for diagnosis of Schistosoma mansoni, soil-transmitted helminths, intestinal protozoa and Plasmodium. Then, a questionnaire survey was carried out for the appraisal of self-reported morbidity indicators, as well as housing characteristics and household assets ownership. Mean travel distance from each village to the nearest health care delivery structure was provided by the regional health authorities. Poorer schoolchildren showed a significantly higher infection prevalence of hookworm than better-off children. However, higher infection prevalences of intestinal protozoa (i.e. Blastocystis hominis, Endolimax nana and Iodamoeba butschlii) were found with increasing socioeconomic status. Significant negative associations were observed between socioeconomic status and light infection intensities with hookworm and S. mansoni, as well as with several self-reported morbidity indicators. The poorest school-attending children lived significantly further away from formal health services than their richer counterparts. Our study provides evidence for inequities among schoolchildren's parasitic infection status, perceived ill health and access to health care in a large rural part of Côte d'Ivoire. These findings call for more equity-balanced parasitic disease control interventions, which in turn might be an important strategy for poverty alleviation.

Protozoarios parásitos de importancia en salud pública transportados por Musca domestica Linnaeus en Lima, Perú

El presente trabajo investiga los protozoarios parásitos de importancia para la salud pública transportados por Musca domestica. El estudio se llevó a cabo entre los meses de junio y diciembre de 1998, en los distritos de Comas y San Juan de Lurigancho de la provincia de Lima. Se estudiaron 3014 moscas colectadas en la basura acumulada en la vía pública de los pueblos jóvenes de los distritos mencionados. Las capturas se agruparon en lotes constituidos por un promedio de 30 moscas. Se estudiaron un total de 100 lotes. Las moscas fueron disecadas y procesadas con agua destilada estéril para obtener un macerado intestinal. Para la observación de los parásitos se utilizó el método directo simple y la coloración tricrómica de Gomori ácido resistente modificado. Se encontraron los siguientes protozoarios que parasitan al hombre: Blastocystis hominis (9,0%), Giardia lamblia (3,0%), Cryptosporidium sp. (2,0%), Cyclospora cayetanensis (1,0%), Iodamoeba bütschlii (17,0%), Endolimax nana (5,0%) y Chilomastix mesnili (3,0%). Se reporta por primera vez para el Perú a B. hominis y Cyclospora cayetanensis en M. domestica.

Intestinal Protozoa in Wild Boars (Sus scrofa) in Western Iran

A total of 12 gastrointestinal tracts of wild boars (Sus scrofa) from western Iran (Luristan) were examined for protozoan infection between September 2000 and November 2001. Of 12 boars examined, 67% harbored one or more species of the following protozoa: Balantidium coli (25%), Tritrichomonas suis (25%), Blastocystis sp. (25%), Entamoeba polecki (17%), Entamoeba suis (8%), Iodamoeba butschlii (17%), and Chilomastix mesnili (8%). Four of these protozoan species also are reported in humans, and persons living in rural areas where wild boars are abundant should take precaution to avoid infection.

Status of intestinal parasite infections among children in Bat Dambang, Cambodia

A survey was conducted to determine the extent of intestinal parasite infection in Bat Dambang, Cambodia in March 2004. A total of 623 fecal specimens was collected from kindergarten and schoolchildren and examined using the formalin-ether sedimentation technique. The overall infection rate of intestinal parasites was 25.7% (boys, 26.2%; girls, 25.1%), and the infection rates of intestinal helminthes by species were as follows: Echinostoma sp. 4.8%, hookworm 3.4%, Hymenolepis nana 1.3%, and Rhabditis sp. 1.3%. The infection rates of intestinal protozoa were; Entamoeba coli 4.8%, Giardia lamblia 2.9%, Iodamoeba butschlii 1.4%, Entamoeba polecki 1.1%, and Entamoeba histolytica 0.8%. There were no egg positive cases of Ascaris lumbricoides or Trichuris trichiura. All children infected were treated with albendazole, praziquantel, or metronidazole according to parasite species. The results showed that intestinal parasites are highly endemic in Bat Dambang, Cambodia.

Stool ova and parasites at a tertiary care center: infrequently positive but multiple organisms present

Cultured stocks of Entamoeba hartmanni, Endolimax nana, Iodamoeba buetschlii and Dientamoeba fragilis were compared with the four Entamoeba histolytica groups already described (Sargeauntet al., 1978), by the electrophoretic patterns of three enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM) and L-malate: NADP+ oxidoreductase (oxalacetate-decarboxylating) (ME). All the species were easily distinguished by their characteristic patterns.

Intestinal Parasites in Gorillas, Chimpanzees, and Humans at Mondika Research Site, Dzanga-Ndoki National Park, Central African Republic

We report prevalences and eggs/protozoa per g (EPG; PPG) of helminths and protozoa in gorillas, chimpanzees, agile mangabeys, indigenous Ba'Aka and Bantu, and western researchers at a remote field site in the Central African Republic. We examined fecal samples for eggs, larvae, proglottids, cysts, amoeba, trophozoites, and flagellates. For helminths, strongylates were most prevalent, infecting 82–94% of nonhuman primates (NH) and 30–93% of human (H) groups, followed by ascaroids (14–88% NH; 0–15% H), and threadworms (0–22% NH; 0–29% H). For protozoa, Entamoeba histolytica (2–100% NH; 33–52% H) and trichomonads (11–88% NH; 0–54% H) were most prevalent. Among gorilla samples (n = 156) there were significant age/sex differences in EPG/PPG for strongylates, threadworms, Entamoeba histolytica, and trichomonads, with infants exhibiting the highest mean EPG/PPG for all parasites except trichomonads. Between group analyses revealed that the Ba'Aka had significantly higher mean EPG of strongylates, ascaroids and threadworms than all other primate groups, except the mangabeys. For Entamoeba histolytica, E. coli, Balantidium coli, and Iodamoeba butschlii, the agile mangabeys had significantly higher mean PPG than other groups; for trichomonads, the chimpanzees, and mangabeys had the highest mean PPG. Relative to other African ape sites, the gorillas and chimpanzees at Mondika appear to have high prevalences of intestinal parasites. This may be the result of the high proportion of swamp and seasonally flooded areas, which provide optimal viability for parasite eggs and ova. At Mondika, the significantly higher parasite levels of Ba'Aka probably result from more traditional methods of hygiene and lack of available medical treatment. All workers at research sites should be monitored and treated to minimize cross-transmission between humans and local fauna.

High prevalence of infection with Entamoeba dispar, but not E. histolytica, in captive macaques.

A total of 268 nonhuman primates (20 species) kept in the Primate Research Institute, Kyoto University, Japan, were surveyed for intestinal amebas. Total positive rates as based on the presence of cysts in the stool following formalin-ether sedimentation were as follows: Entamoeba histolytica/E. dispar, 53%; E. coli, 34%; E. hartmanni, 34%; Iodamoeba buetschlii, 25%; Endolimax nana, 8%; and E. chattoni, 3%. Positive rates were higher in Old World monkeys and lower in New World monkeys. All the 141 E. histolytica/E. dispar-positive animals were Macaca monkeys. The E. histolytica/E. dispar-positive samples were analyzed by polymerase chain reaction (PCR) for identification of E. histolytica and E. dispar. E. dispar DNA was detected in 137 samples, whereas no E. histolytica DNA was seen. Zymodeme analysis and reactivity to monoclonal antibodies of cultured trophozoites also supported the presence of E. dispar and the absence of E. histolytica. When the sera of 93 macaques were examined by an indirect fluorescent antibody test, only 3 animals proved to be positive for E. histolytica, showing the lowest titer. These results demonstrate that infection with E. dispar, but not E. histolytica, is predominant in macaques.

Gastrointestinal parasites of mountain gorillas (Gorilla gorilla beringei) in the Parc National des Volcans, Rwanda.

Ninety-eight fecal samples were collected from 74 free-living mountain gorillas (Gorilla gorilla beringei) from the Parc National des Volcans, Rwanda, between July 1995 and January 1997 and examined for parasites by Sheather's sugar and zinc sulfate flotation methods, trichrome staining, and larval cultures. All samples contained at least one parasite. Seventeen endoparasites were identified, including eight protozoa, seven nematodes, one cestode, and one trematode. Two species of arthropod mite were also recovered from the fecal samples. Parasites observed on fecal examinations included strongyle/trichostrongyle-type eggs (72/74) (representing Oesphagostomum sp., Trichostrongylus sp., Hyostrongylus spp., and possibly Murshidia sp.), Strongyloides sp. (1/74), Trichuris trichiura (2/74), Probstmayria sp. (7/74), Anoplocephala sp. (63/74), Entamoeba hartmanni cysts and trophozoites (19/70), Endolimax nana cysts (31/70), Iodamoeba buetschlii cysts (11/70), Endolimax nana or Iodamoeba buetschlii trophozoites (63/70). Entamoeba coli cysts and trophozoites (14/70), Entamoeba histolytica trophozoite (1/70), Chilomastix sp. cysts and trophozoites (31/70), and Giardia sp. cysts (2/70). In addition, one ascarid and one trematode egg were seen. There were no significant differences in the prevalence of parasites between males and females and between age groups: however, infants and juveniles appeared to have a lower prevalence of Anoplocephala gorillae, and the silverbacked males appeared to have a higher prevalence of Probstmayria sp. Parasite prevalence was consistent among the five social groups studied except Susa group had a significantly lower prevalence of Anoplocephala gorillae. Trichuris trichiura, Strongyloides sp., Chilomastix sp., and Endolimax nana were identified for the first time in this population, and it is possible that these parasites were of human origin. Although there were no obvious clinical effects due to the presence of these parasites, six parasites identified (Trichuris trichiura, Strongyloides sp., Oesphagostomum sp., Trichostrongylus sp., Entamoeba histolytica, and Giardia sp.) could potentially be pathogenic. Some of the parasite products and cultured larvae could not be speciated.

Entamoeba dispar, but not E. histolytica, detected in a colony of chimpanzees in Japan.

Chimpanzees (Pan troglodytes) residing in the Kumamoto Primate Research Park, Sanwa Kagaku Kenkyusho, were surveyed for the presence of intestinal parasites. Stool samples from 107 chimpanzees were examined by microscopy after formalin-ether sedimentation. Of these animals, 100 were infected with at least 1 species of ameba. The positivity rates recorded were as follows: Entamoeba coli, 88%; E. histolytica/E. dispar, 48%; E. hartmanni, 15%; Iodamoeba buetschlii, 8%; Endolimax nana, 4%; and Entamoeba chattoni, 2%. Polymerase chain reaction (PCR) analysis to distinguish between E. histolytica and E. dispar was performed on these samples. E. dispar DNA was detected in 60 of 107 samples (56%), including 9 that had been microscopically determined to be negative for E. histolytica/ E. dispar. In contrast, no E. histolytica DNA was detected in the 107 samples. Zymodeme analysis indicated that 10 isolates were E. dispar. When 104 chimpanzees were examined serologically for E. histolytica infection, 1 sample was scored as positive by indirect hemagglutination and another was found to be positive by an indirect fluorescent antibody test. However, both specimens were borderline-positive and were clearly negative in other tests, suggesting that they might be false-positives. These results demonstrate that the pathogenic E. histolytica was absent in this colony, regardless of the high degree of prevalence of other amebas. For an accurate diagnosis, PCR analysis is recommended in addition to microscopic examination.

A small-scale survey of intestinal parasite infections among children and adolescents in Legaspi city, the Philippines.

To determine the status of infection caused by intestinal parasites among children and adolescents living in Legaspi city, the Philippines, we performed a small survey by fecal examination for helminth ova and protozoan cysts with formalin-ether concentration method. Of the 64 examinees, the infection rate was 78.1%. The infection rates of primary school children, preschool children and adolescents were 95.5%, 64.7% and 87.5%, respectively. The infection rate in urban areas was 56%, and 92.3% in rural areas. The infection rates were 51% with Trichuris trichiura, 40% with Ascaris lumbricoides, 23.4% with hookworm, 15.6% with Iodamoeba butschlii, 14.1% with Endolimax nana, 9.4% with Entamoeba coli and 7.8% with Giardia lamblia. There were 33 cases with multiple infection (51.6%). Mixed infection with more than 3 parasites was observed in 15 cases, all of them being children and adolescents living in rural areas. By this survey, it was conjectured that helminthic infection is prevalent among children and adolescents in Legaspi, Philippines.

Evaluation of Streck tissue fixative, a nonformalin fixative for preservation of stool samples and subsequent parasitologic examination.

We undertook a study to evaluate Streck tissue fixative (STF) as a substitute for formalin and polyvinyl alcohol (PVA) in fecal preservation. A comparison of formalin, PVA, (mercuric chloride based), and STF was done by aliquoting fecal samples into each fixative. Stool specimens were collected in Haiti, and parasites included Cyclospora cayetanensis, Giardia intestinalis, Entamoeba coli, Iodamoeba butschlii, Endolimax nana, Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, and Necator americanus. Preserved stools were examined at various predetermined times (1 week, 1 month, and 3 months) to establish the quality of the initial preservation as well as the suitability of the fixative for long-term storage. At each time point, stool samples in fixatives were examined microscopically as follows: (i) in wet mounts (with bright-field and epifluorescence microscopy), (ii) in modified acid-fast-, trichrome-, and safranin-stained smears, and (iii) with two commercial test kits. At the time points examined, morphologic features remained comparable for samples fixed with 10% formalin and STF. For comparisons of STF- and 10% formalin-fixed samples, specific findings showed that Cyclospora oocysts retained full fluorescence, modified acid-fast- and safranin-stained smears of Cryptosporidium and Cyclospora oocysts were equal in staining quality, and results were comparable in the immunofluorescence assay and enzyme immunoassay commercial kits. Stool fixed in STF and stained with trichrome showed less-than-acceptable staining quality compared with stool fixed in PVA. STF provides an excellent substitute for formalin as a fixative in routine examination of stool samples for parasites. However, modifications to the trichrome staining procedures will be necessary to improve the staining quality for protozoal cysts fixed in STF to a level comparable to that with PVA.

Stool Examinations in Immigrant New School Enrollees in New York City† 659

The Bureau of School Health (BSH) of the New York City Department of Health(NYCDOH) is mandated by law to provide new-admission health assessments for all children without primary health care providers enrolling in school for the first time. A stool examination is not a part of the routine new admission evaluation. From 1990-1994, New York City received 562,988 immigrants (14.6% of the U.S. total), many from countries where intestinal parasites pose a significant health problem. The majority of immigrants came from the Caribbean(33%), Asia (26%), South America (12%), and Africa (2%); and 13.6% of these immigrants settled in the Bronx. During a four month period (March-June 1996) single, fresh stool specimens from asymptomatic new school enrollees seen at a BSH Clinic in the Bronx were submitted to the DOH Bureau of Laboratories. One hundred and nineteen children were evaluated with the following results: age range 4-18 years (mean 10 yrs.); 43 (36%) females, 76 (64%) males; 41 (34%) black; 62 (52%) hispanic. Most of these children came from the Dominican Republic 45 (38%), Ghana 22 (18.5%), and Jamaica 10 (8%). One child was a U.S.-born citizen. All children were asymptomatic and free of significant underlying illness. Stool examinations were positive for 88 (74%) children. The most commonly identified parasites of clinical significance included Blastocystis hominis 62 (71%), Entamoeba histolytica 21(24%), Giardia lamblia 18 (21%), Ascaris lumbricoides 5(6%), hookworm 5 (6%), and Trichuris trichiura 2 (2%). Other parasites identified included Endolimax nana 39 (44%),Iodamoeba butschlii 25 (28%), Entamoeba hartmani 18 (21%),Entamoeba coli 12 (14%), and Chilomastix mesnili 3 (3.4%). Multiparasitism was very common. A second sampling of 94 symptomatic children at a BSH clinic in Queens confirmed an equally high rate (73%) of intestinal parasites among immigrant children, with the addition of Strongyloides stercoralis (2%) as an important pathogen. The impact of such infections on the health and development of the school-aged immigrant population in New York City needs to be better defined, as well as the need to consider stool examinations as part of the health evaluation of these children.

Prevalence of intestinal parasitic infection in five farms in Holambra, São Paulo, Brazil.

A parasitological survey was carried out on 222 inhabitants of five farms in Holambra, located 30 km north of Campinas, São Paulo, Brazil, on October 1992. Approximately 70% of the inhabitants were found to be infected with at least one species of intestinal parasite. The positive rates of 6 helminths and 7 protozoan species detected are as follows: 5.4% Ascaris lumbricoides; 8.6% Trichuris trichiura; 19.8% Necator americanus; 10.4% Strongyloides stercoralis; 1.4% Enterobius vermicularis; 0.9% Hymenolepis nana; 3.2% Entamoeba histolytica; 2.7% E. hartmanni; 9.9% E. coli; 14.0% Endolimax nana; 2.3% Iodamoeba butschlii; 10.4% Giardia lamblia; 37.8% Blastocystis hominis. The positive rates of helminth infection were generaly higher in the younger-group under 16 years-old than those in the elder group aged 16 or more, whereas the infection rates of protozoan species were higher in the elder group. The infection rate of Strongyloides was found to be 10.4% by a newly developed sensitive method (an agarplate culture methods).

Intestinal parasite and Clonorchis sinensis infection among the inhabitants in the upper stream of Taechong Dam, Kumgang (River)

The prevalence of intestinal parasites and Clonorchis sinensis infection was observed among inhabitants in the upper stream of Kumgang (River) from January to October 1991. A total of 743 fecal specimens was examined by cellophane thick smear and formalin-ether concentration technique. The parasite positive rate including helminth eggs and protozoan cysts was 40.8%, the positive rates for every species were: Clonorchis sinensis 30.8%, Metagonimus spp. 14.5%, Fasciola spp. 0.7%, Taenia spp. 1.5%, Ascaris lumbricoides 0.4%, Enterobius vermicularis 0.1%, Hookworm 0.1%, Trichuris trichiura 1.6%, Entamoeba coli 0.7%, E. histolytica 0.3%, Endolimax nana 0.3%, Giardia lamblia 0.3% and Iodamoeba buetschlii 0.1%, respectively. The cumulative positive rate in Okchon-gun showed 51.1%, in the Kumsan-gun 50.8% and in the Muju-gun 28.6%. Through this survey, it was concluded that the soil transmitted intestinal parasites including helminthseggs and protozoan cysts have been decreased remarkably among the inhabitants along the upper stream of Taechong Dam, Kum-gang (River), on the other side, Clonorchis sinensis, Metagonimus spp. and Taenia spp. are still morderate prevalent.

Production and characterization of monoclonal antibodies against a highly immunogenic fraction of Entamoeba histolytica (NIH:200) and their application in the detection of current amoebic infection.

Six monoclonal antibodies (MAbs) were produced against a highly immunogenic fraction derived by the chromatographic separation of the soluble preparation of axenic Entamoeba histolytica (strain NIH:200) trophozoites. Isotype characterization of the six MAbs revealed that four belonged to the IgM class and one each to the IgG1 and the IgG2a subclasses. The immunoreactivity patterns and the specificity of the MAbs with homologous and heterologous antigens were analyzed by the enzyme-linked immunotransfer blot technique and by the enzyme-linked immunosorbent assay. The MAbs reacted intensely with isolates of E. histolytica (strain NIH:200 as well as a local isolate MX1) but showed no reactivity with Entamoeba coli, Iodamoeba butschlii, Endolimax nana, Entamoeba hartmanni, free-living amoeba (Acanthamoeba harticolus) and other enteric parasites. Using the IgG1 MAb as a detecting antibody, a polyclonal-monoclonal antibody-based enzyme-linked immunosorbent assay was developed for the detection of E. histolytica antigens in stool samples of infected patients. The detection limit of the assay was 8 ng of amoebic antigen. This test was found to be specific and sensitive and yielded 100% positive results in cases with amoebiasis but did not react with controls included in the evaluation. The MAb-based enzyme-linked immunosorbent assay developed in this study will be an important test for the diagnosis of E. histolytica in the feces of infected humans; however, the limitation of the test is the inability to discriminate the pathogenic status of the amoeba detected in the stool.

Status of intestinal parasite infections in inhabitants of Palmar, Guayas Province, Ecuador

Status of intestinal protozoan and helminthic infections was surveyed in mestizo population living in rural parish of Palmar and its nearby recintos(villages). Three of the surveyed villages were at the Pacific coast and 5 villages were in inner pasture land, located about 100 km west of Guayaquil, the second largest city in Ecuador. One stool sample was examined by one cellophane thick smear for helminth ova and one direct smear stained with Lugol's iodine solution for protozoan cysts. Of 325 persons examined, 66.1% were positive for any ova or cyst. The positive rates were: 18.1% for Ascaris lumbricoides, 19.4% for Trichuris trichiura, 0.6% for hookworm, 3.7% for Hymenolepsis nana, 1.8% for Taenia sp., 19.4% for Entamoeba histolytica, 28.6% for Entamoeba coli, 5.5% for Endolimax nana, 1.5% for Iodamoeba buetschlii, 11.1% for Giardia lamblia and 0.6% for Chilomastix mesnili. Poor supply of potable water was considered the main cause of high prevalence of intestinal protozoan infections.

A survey of gastrointestinal parasites in Ogun State, southwest Nigeria.

To study the epidemiology of intestinal parasites in Ogun State, Nigeria, 479 stool specimens were examined at a hospital in Abeokuta during the rainy season in June 1986. Intestinal helminths and/or protozoa were present in 297 samples (62%). 41.1% of the specimens showed a single infection, 34% showed double, 20% triple and 5% quadruple infection. The most commonly found worm was Ascaris lumbricoides (in 40% of specimens), followed by Trichuris trichiura (23.2%), hookworms (19.2%), Strongyloides stercoralis (2.1%) and Dicrocoelium sp. (0.4%). Pathogenic protozoa found were Entamoeba histolytica (7%), Giardia intestinalis (4.2%), Blastocystis hominis (2.5%) and Cryptosporidum sp. (2.3%). The apathogenic protozoa Entamoeba coli, Chilomastix mesnili, Trichomonas hominis and Iodamoeba buetschlii were also seen.

An enzyme-linked immunosorbent assay for the detection of Entamoeba histolytica antigens in faecal material

This paper describes a method for the detection of Entamoeba histolytica antigens in stool samples using a multi-layer ELISA. The method is sensitive and specific, showing no interference with other intestinal parasites, e.g. E. coli, E. hartmanni, Endolimax nana, Iodamoeba buetschlii, Hymenolepis nana, Giardia lamblia, Trichomonas and Ascaris. The method provides a rapid and simple screening assay for E. histolytica infections and should assist in diagnosis and epidemiological studies of the disease.

Parasitological surveys in the Jos Plateau, Nigeria.

Surveys for schistosomiasis, intestinal parasitic infections and filariasis were carried out in 3 villages of the Jos Plateau, Nigeria, in the period between February and March, 1985. Of 668 fecal samples, 66.8% were found to harbour parasitic eggs and protozoa. The overall prevalence of parasitic infections among villagers was as follows : hookworm, 40.3%; Ascaris lumbricoides, 9.1%; Strongyloides stercoralis, 0.3%; Trichuris trichiura, 0.4%; Schistosoma mansoni, 18.9%; Taenia sp., 0.1%; Hymenolepis nana, 0.1%; and cysts of Entamoeba histolytica, 6.7%; Entamoeba coli, 31.4%; Iodamoeba butschlii, 11.1%; Endolimax nana, 2.5%; Chilomastix mesnili, 1.6%; Giardia lamblia, 1.5%. Hookworm was the predominant helminth, and the infective larvae of Necator americanus were found in 6 pupils using filter paper-cultures. The prevalence rates of hookworm infection varied significantly with villages; 53.9% at Sop, 33.3% at Jebu and 6.0% at Maigemu. Of the 344 inhabitants, 5.2% and 13.4% were found to harbour microfilariae of Loa loa and Dipetalonema perstans, respectively. Factors which may have contributed to the spread of these parasitic infections on the Jos Plateau are discussed.