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Giardia intestinalis is one of the most common causes of parasite-induced diarrhea, abdominal pain, flatulence, and malabsorption. Yet, data on the epidemiology of G. intestinalis infections in North Africa are limited. The purpose of this study was to carry out a retrospective survey on the level of intestinal parasitism with a particular emphasis on G. intestinalis in children and adults in Algiers, Algeria. A total of 2,054 individuals from outpatient clinics or hospitalized at Beni-Messous University Hospital of Algiers undergoing stool microscopy for ova and parasites were included. The overall parasite infection rate was 28%. In the 567 parasite-positive samples, Blastocystis was found most frequently (57.3%), followed in frequency by Endolimax nana (41.0%), Entamoeba histolytica/dispar (19.6%), G. intestinalis (17.1%), Entamoeba coli (13.9%), Chilomastix mesnili (1.0%), Iodamoeba bütschlii (0.7%), Entamoeba hartmanni (0.5%), and Cryptosporidium spp. (0.2%). Intestinal parasites were generally more common in adults than in children, except for Giardia, which was more common in children (P = 0.0001). Giardia infection was independent of gender (P = 0.94). Compared with other intestinal parasitic infections, clinical manifestations, such as abdominal pain (P = 0.28) and diarrhea (P = 0.82), were found not to be significantly linked to Giardia infection. In conclusion, G. intestinalis is common in individuals referred to the University Hospital of Beni-Messous with digestive symptoms, particularly so in children. However, in our study, intestinal symptoms appeared not to be more linked to Giardia than to other intestinal parasites.

Intestinal parasitic infection rate among school-aged children in Thailand has been decreasing. However, certain intestinal parasites remain problematic in some regions. This cross-sectional study was conducted between February and September 2016 in three suburban government primary schools (KK, BR, and HK), Saraburi, Thailand. Stool was collected from 263 asymptomatic subjects (4–15 years old), using simple direct smear, formalin–ether concentration, Boeck and Drbohlav’s Locke–Egg–Serum (LES) medium culture, and agar plate culture. A self-administered questionnaire was used to collect data about lifestyle and socioeconomic status. The overall rate of intestinal parasites was 22.1% (15.6% single infection and 6.5% multiple infections). The helminths involving the digestive system found were Strongyloides stercoralis (1.5%) and Opisthorchis viverrini (0.4%). For protozoan infection, the major cause was Blastocystis hominis (17.5%). The other protozoa included Endolimax nana (4.6%), Entamoeba coli (3.4%), Entamoeba histolytica/Entamoeba dispar (1.1%), and Giardia intestinalis (0.8%). The sensitivity for the detection of B. hominis increased with the LES culture technique. The infection rate of each organism was not significantly different among the three schools except for B. hominis which showed the highest prevalence in the HK school (P = 0.001). This was correlated with the questionnaire results in which the HK school showed the highest risk of drinking contaminated water (P = 0.004). The present study emphasized the persistent problems of protozoan infections among suburban school-aged children. Lifestyle was still an important factor for intestinal parasitic infections among suburban school-aged Thai children in this study. Health education as well as routine surveillance was necessary to control the infections.

Children in the Bolivian Andes are exposed to endemic infections and meager nourishment, and live under poor hygienic conditions. The prevention of children malnutrition is a priority in many countries including Bolivia. In this study, the health status of schoolchildren in Taraco, a Puna district, at 4,000 meters above sea level (masl) and in Caranavi, at 650 masl in the wealthier subtropical valleys, was compared. The weight, height, and hematological and biochemical parameters in blood, parasites in stool, and clinical information in 120 children from rural Taraco and in 96 from semi-urban Caranavi, both predominantly of Aymara ethnicity, were registered. Eleven percent of Taraco children were undernourished compared with 3% in Caranavi. Instead, 41% of the children in Caranavi were obese or overweight, compared with 8% in Taraco. Anemia was found in 74% of the children in Taraco compared with 7% in Caranavi. Albumin levels were normal in all samples, albeit lower in Taraco. Similar and normal serum zinc levels were measured in both groups. Approximately 60% of the children in both locations showed insufficient vitamin D levels, with lower levels in Taraco children. Hymenolepis nana and Entamoeba coli, parasites determinant of poor hygienic conditions, were respectively detected in 78% and 21% of fecal samples from Taraco, and in 29% and 8% of samples from Caranavi. We show increased anemia, nutritional deficiencies, and indications of poor hygienic conditions in highlands compared with lowlands. The prevalence of obesity in the lowlands demands addressing diverse nutritional deficiencies in the regions of Bolivia.

The aim of the present study was to assess the frequency of intestinal parasitic infection among patients with gastrointestinal tract disorders from the Greater Cairo region, Egypt. In addition, a comparison was made of the accuracy of direct thin and thick smear, formol-ether sedimentation (FEC), centrifugal flotation (CF), and mini-FLOTAC techniques in the diagnosis of infection. Out of 100 patients, the overall prevalence of parasitic infection was 51%. Only 6% had dual infection. Giardia lamblia was the most common parasite (26%), followed by Hymenolepis nana (20%), Entamoeba coli (8%), and Enterobius vermicularis (3%). Except the statistically significant association between E. vermicularis infection and perianal itching and insomnia (P < 0.001), age, gender, and complaints of the examined individuals had no association with prevalence of parasitic infection. Both FEC and CF were equally the most accurate techniques (accuracy = 98.2%, confidence interval [CI] = 0.95–1.0, and κ index = 0.962), whereas the Kato-Katz method was the least accurate (accuracy = 67.5%, CI = 0.57–0.78, and κ index = 0.333). However, mini-FLOTAC-ZnSO4 was the most accurate for diagnosis of helminthic infection, and FEC was more accurate for diagnosis of protozoal infection (accuracy = 100%, CI = 1.0–1.0, and κ index = 1).

We assessed the prevalence of intestinal parasites among 268 2–12-year-old children living in rural areas, small villages, and semi-urban areas of the Chaco region, south-eastern Bolivia. The overall parasitism was 69%. Only protozoa, helminths, or co-infections were observed in 89.2%, 5.9%, or 4.9% of the positive children, respectively. A significant progressive increase in overall parasite prevalence was found when passing from rural areas to small villages and semi-urban areas. The most commonly found species were Entamoeba coli (38.4%), Giardia intestinalis (37.7%), and Blastocystis spp. (16%). Hymenolepis nana was the most prevalent helminth (5.6%), followed by Ascaris lumbricoides and hookworms (1.5% and 0.4%) evidenced only in rural areas and in villages. Molecular diagnostics identified Blastocystis subtypes 9 and 2, and 5 infections by Entamoeba histolytica and 4 by Entamoeba dispar. The dramatic decrease in prevalence of soil-transmitted helminths with respect to that observed about 20 years ago (> 40%) evidences the success of the preventive chemotherapy intervention implemented in 1986. Health education and improved sanitation should be intensified to control protozoan infections.

Kaposi sarcoma (KS) is endemic in Uganda and shares several risk factors with intestinal parasite infestation, including rural residence, contact with surface water, and walking barefoot, however, the significance of these ecologic relationships is unknown. We investigated these relationships among 1,985 Ugandan patients with cancer. Odds ratios (OR) were calculated using logistic regression. KS patients had higher carriage of Strongyloides stercoralis larvae (OR 2.1, 95% CI 1.2-3.7) and lower carriage of hookworm ova (0.6, 0.4-1.0) and Entamoeba coli cysts (0.7, 0.5-1.0), after adjusting for region of residence, age, gender, and diagnosis. While our findings may be due to confounding, they are compatible with shared risk factors or etiological association between parasites and KS, and warrant well-designed follow up studies.

An epidemiologic field study was conducted in the village of Borbòn in Esmeraldas province in northern Ecuador to compare different parasitologic methods in the diagnosis of infection with the Entamoeba histolytica/Entamoeba dispar complex. The results of two stool antigen detection assays (the Prospect Entamoeba histolytica microplate assay and the E. histolytica II assay) were compared with isoenzyme characterization of the amebic isolates. Nearly all (176 of 178, 98.9%) subjects were positive for intestinal parasites on direct microscopic examination, and cysts and/or vegetative forms morphologically consistent with the E. histolytica/E. dispar complex were recorded in 48 of 178 cases (27%). Culture in Robinson's medium was positive for amebic stocks in 89 (50%) of the 178 samples tested. Of the 37 isolates successfully stabilized, cloned, and characterized by zymodeme analysis, seven (18.9%) showed isoenzyme patterns of E. histolytica, whereas 26 (70.3%) showed patterns of E. dispar. The remaining four strains were identified as Entamoeba coli (three isolates; 8.1%) and Dientamoeba fragilis (one strain; 2.7%).The immunochromatographic tests showed different degrees of sensitivity and specificity when compared with isoenzyme characterization as the reference technique. The microplate assay, which does not discriminate between E. histolytica and E.dispar, showed a sensitivity of 54.5% and a specificity of 94% for both these amebic species. In contrast, the second-generation E. histolytica II test had a sensitivity of 14.3% and a specificity of 98.4% for E. histolytica sensu stricto. Our survey clearly demonstrated that more specific and sensitive diagnostic tests, such as stool antigen detection assays and isoenzyme analysis, are needed to establish the actual worldwide distribution of E. histolytica and E. dispar.

To document patterns of intestinal parasitism in the United States, we analyzed results of 216,275 stool specimens examined by the state diagnostic laboratories in 1987; parasites were found in 20.0%. Percentages were highest for protozoans: Giardia lamblia (7.2%), Entamoeba coli and Endolimax nana (4.2% each), Blastocystis hominis (2.6%), and Entamoeba histolytica (0.9%). The most commonly identified helminths were nematodes: hookworm (1.5%), Trichuris trichiura (1.2%), and Ascaris lumbricoides (0.8%). Identifications of G. lamblia increased broadly from the 4.0% average found in 1979, with 40 states reporting increases and seven reporting decreases. Seasonally, Giardia identifications increased in the summer and fall, especially in the Midwest. Nine states reported hookworms in more than 2% of specimens; none were states with indigenous transmission. We analyzed similar, but abbreviated, data for 1991; parasites were found in 19.7% of the 178,786 specimens and Giardia was found in 5.6%. States reporting percentages of Giardia identification in the highest quartile for both 1987 and 1991 were located in the Midwest or in the Northwest. Cryptosporidium was identified in both the 1987 and 1991 surveys; it had not been identified in a previous survey. For each year, Cryptosporidium was reported from 25 states across the country (for both years in 17 states). We conclude that intestinal parasitism should not be overlooked as a cause of gastrointestinal illness in the United States and that the prevalence of Giardia may be increasing.

We used the polymerase chain reaction (PCR) to study the epidemiology of pathogenic and nonpathogenic Entamoeba histolytica in a rural community in Mexico. Formalin-fixed stool samples were used for extraction of DNA. The PCR amplifications were performed using two sets of primers that discriminate between pathogenic or non-pathogenic E. histolytica. A total of 201 randomly selected individuals were studied. Among them, 25 (12%) were diagnosed to be infected with E. histolytica by microscopy; PCR identified 24 of these as positive (sensitivity = 0.96) and of 176 negative individuals, only three were identified as positive (specificity = 0.98). The PCR analysis defined three populations: 14 cases were positive for both pathogenic and nonpathogenic E. histolytica, nine cases were positive for pathogenic and negative for nonpathogenic E. histolytica, and only one case was negative for pathogenic and positive for nonpathogenic E. histolytica. Infection by E. histolytica was strongly associated to infection with Entamoeba coli (odds ratio [OR] = 9.41, 95% confidence interval [CI] = 3.09, 28.65, P < 0.0004) and Endolimax nana (OR = 6.15, 95% CI = 2.03, 18.17, P < 0.0004). This new technique has high specificity and sensitivity; it is simple, reproducible, fast, avoids the need to culture trophozoites, and can be applied in the field for epidemiologic studies.

Fecal samples were obtained from 722 of 820 children attending 7 nursery schools and 1 primary school in the city of Santiago, Chile. Microscopy of formol-ether concentrates showed that 33% of the children were infected with Giardia lamblia. Prevalences among primary school students (5-10 years of age) of G. lamblia (38%), Endolimax nana (43%), and Entamoeba coli (25%) were overall higher than among nursery school students (3 months-5 years of age; prevalences 29%, 21%, and 16%, respectively). There was no apparent association between socio-economic intake and levels of G. lamblia infection: the private nursery school had the highest recorded level of infection (40%). One hundred sixty-two triplicate stool specimens were used to compare microscopy with an enzyme-linked immunosorbent assay (ELISA) for the detection of Giardia fecal antigens. The ELISA was highly sensitive and specific either visually (95% and 97%, respectively) or by optical density determination (99% and 96%, respectively). Incorporation of non-immune rabbit immunoglobulin-coated control wells did not enhance sensitivity and specificity. The antigen detection ELISA is an extremely effective tool for the epidemiological investigation of giardiasis.

The isolated Lake Lindu Valley of Central Sulawesi is the only reported Indonesian focus of oriental schistosomiasis. In April 1972 a parasitological survey involving over 1,400 people was conducted in the valley's four villages. Schistosoma japonicum infections were detected in 37.9% of all Lindu people by direct and formalin-ether concentration examinations of stools: 57.1% in Anca, 42.4% in Tomado, 30.0% in Langko, and 11.7% in Puroo. Peak prevalences of schistosomiasis were reached in the second decade of life and remained high thereafter among both male and female populations. Prevalences of other helminthic parasites are reported as follows: Hymenolepsis diminuta

Summary The relation of canned salmon diet to amebic colitis was studied in two groups of dogs comprising twelve fed exclusively on canned salmon and four on normal diet, either inoculated with Entamoeba histolytica or not inoculated. One group of dogs was intubated transrectally with a glass tube three times a week; the other group was not intubated. Hookworms and whipworms were eliminated or reduced to negligible numbers. The character of the stools was recorded daily and the condition of the cecum and colon, fixed immediately after sacrifice, was observed histologically. The dogs on salmon diet developed varying degrees of mucoid diarrhea and dysentery, the intensity of which was in direct relationship to the amount of salmon consumed. The pathology observed in such dogs was characteristic of a chronic nonspecific inflammation of the intestinal mucosa. Infection with E. histolytica, when present, did not have any determining effect upon the enteric symptoms; neither did amebae markedly change the pathology observed. The irritative action of the diet was clearly enhanced by frequent colonic aspiration, the combination of the two factors regularly producing dysentery in the dogs thus treated. In one dysenteric dog infected with mixed cysts of three ameba species a colony of amebae (presumably Entamoeba coli) was seen in the sloughed mucosa in approximately the same location where colonies of E. histolytica had been found in other dogs. The control dogs on horse meat diet passed consistently normal stools, regardless of whether or not they were infected with E. histolytica or harbored hookworms or whipworms. Transrectal intubation of such dogs produced only small amounts of blood and mucus in the stools following aspiration. It is felt that the salmon diet is the main causative factor in the development of this dysenteric syndrome in the dog, acting as a local irritant upon the intestinal mucosa and causing a nonspecific type of colitis with sloughing of the mucosa and output of bloody mucus. Amebae may aid, when present, in the causation of symtoms but no evidence was found of their being primary invaders of the tissues of the dog. Hookworms are not considered to be an important factor in this process.

Summary The digestive tracts and excrement of dung beetles were examined after ingestion of human feces containing the eggs of hookworm, Ascaris, and whipworm, and cysts of Entamoeba coli, Endolimax, and Giardia. Practically no eggs and few cysts were recovered from Canthon laevis and C. vigilans, and no Ascaris larvae were found in the former after the ingestion of embryonated eggs. From Phanaeus vindex and Ph. igneus unaltered whipworm eggs and more cysts, but no hookworm and few Ascaris eggs, were recovered. Only Pinotus carolinus, the largest species, regularly contained and excreted ingested eggs. Recovered Ascaris eggs were decorticated and sometimes crushed, but many from the gut of Pinotus proved viable when incubated. Destruction of eggs and cysts is attributed to the grinding action of the beetles' mandibles, which is evidently least efficient in Pinotus. Although dung beetles may be significant in other ways in the dissemination of hookworm, the species most abundantly attracted to human stools destroy ingested eggs of this parasite and of Ascaris and do not transport them internally.

Summary Although our study material was represented by fecal preparations from more than 1,400 Egyptians, the number of species of protozoa found was not greater than observed in our previous studies involving far smaller samples of the population. Larger population samples, however, more strongly emphasize that the relationship between type of locality and presence of intestinal protozoans, and that between locality and prevalence of helminths, must be considered separately. Their establishment is dependent upon different means of transmission. Undoubtedly many of the protozoa are passed from person to person by contaminated hands and by food contaminated by hands and/or flies. Many of the peoples in this part of the world are unhygienic in their habits and one heavily contaminated hand thrust into a bowl which serves the entire family provides an effective vector of protozoan cysts and, in some instances, probably trophozoites. These modes of transfer are not greatly influenced by the unusually dry habitats in which many of the Egyptian peoples live. This conclusion is supported by the high incidence of intestinal protozoa in the semi-desert and desert communities. Entamoeba coli is the most common intestinal protozoan among the Egyptian peoples and the total incidence of the large and small races of E. histolytica is much greater than that listed for other parts of the world. Perhaps the majority of the population would have been found harboring both species had a series of specimens from each person been examined. Balantidium coli was not detected in our studies and Isospora hominis occurred in only two persons. This study of materials from a wide range of community types demonstrates the relationship between parasitism by some of the helminths and the habitat in which these peoples live. This was to be expected since successful establishment of infection involves intermediate hosts and favorable conditions for proper maturation of the helminth eggs outside the human body. The present study lists 19 helminths, several species of which, (e.g., Opisthorchis, Haplorchis, Dicrocoelium and Fasciola of the Trematoda, and the cestode, Diphyllobothrium) are not considered parasites ordinarily found among the Egyptian peoples. Ascaris is the most common helminth and hookworm (Ancylostoma) apparently is much

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Entamoeba histolytica in human feces, using both a monoclonal antibody and rabbit antisera. It detected from less than 1 to 57 trophozoites of 6 E. histolytica strains. Stool specimens were positive by ELISA in 18 of 22 (82%) patients with E. histolytica and in 3 of 186 (2%) of patients without demonstrable E. histolytica in their stools. The latter included one from a child living near an asymptomatic cyst carrier and another from a traveler with giardiasis who had recently taken antibiotics. One hundred eight of 183 microscopy-and ELISA-negative specimens contained other parasites including Giardia (49 specimens), Endolimax nana (24), Entamoeba coli (21), Iodamoeba butschlii (2), and Entamoeba hartmanni (1). This ELISA for E. histolytica is a simple, sensitive and specific diagnostic tool.

Labrador, a previously unsurveyed area of Canada, has been sampled for human intestinal parasites. Four hundred and one asymptomatic volunteers between 1 and 72 years of age, including Inuit, Naskapi and whites, were examined during the summer of 1977. They harboured: Entamoeba coli, E. histolytica, E. hartmanni, Giardia lamblia and Diphyllobothrium sp. The infection rates are considerably lower than those found in other studies of Northern Canadian communities.

A stool survey of about one-half the permanent population of Aspen, Colorado, was undertaken after an outbreak of giardiasis during the 1965–66 ski season. The prevalence of parasites, viruses, and enteric bacterial pathogens was determined. The chlorazol-black staining technique for fecal films was evaluated and found to be a simple, efficient technique for obtaining permanent stained slides in field studies. Parasitologic examinations of this middle-to-upper income population showed a Giardia lamblia infection rate of 5.0%, significantly higher than the prevalence of both Entamoeba coli and Endolimax nana (1.9%). Only about 1% of the 280 stools cultured were positive for enteric pathogens. Six polioviruses, antigenically classified as vaccine-like, four adenoviruses, and one untyped enterovirus were isolated from the 416 stools examined. No person was doubly infected with parasites, bacteria, or viruses.

Summary The incidence of intestinal protozoa and helminths in a total of 1089 persons (mixed ages, backgrounds, localities, ethnic groups, etc.) in the Colony of British North Borneo was determined by examination of a single stool specimen by the direct smear (MIF) and the MIFC concentration techniques. Overall prevalences for the protozoa were much less than expected in an area where epidemiological conditions appeared to favor parasitization. Entamoeba histolytica occurred in only 0 to 3% of seven groups of people, indicating that amebiasis may not necessarily be a disease of great concern in all populations of the tropics. Other protozoa also occurred in limited numbers, i.e., Entamoeba hartmanni, 0 to 12%; Entamoeba coli, 4 to 30%; Endolimax nana, 2 to 12%; and Iodamoeba butschlii, 0 to 2%. Giardia and Chilomastix occurred in 3 to 16 and 0 to 1% respectively of the people examined. Hookworm (27 to 72%), Ascaris (13 to 74%), and Trichuris (41 to 89%) infections were commensurate with epidemiological conditions in the area, but Trichostrongylus was not recorded. Hymenolepis and Taenia were rare and Clonorchis occurred only in Chinese who probably acquired infections outside Borneo. Several persons passed eggs of heterophyid and unidentified trematodes.