Water contact and Schistosoma haematobium infection: a case study from an upper Egyptian village.

The quantitative relationship between water contact and Schistosoma haematobium infection was studied in a cohort of male school children aged 6-17 in El Ayaisha village, Upper Egypt, during a two-year study. An exposure index (total body minutes, TBM) was used to identify the activities responsible for exposure to cercariae-infested water and to examine the relationship between water contact and infection. Results show that 65% of all contacts and 86% of all TBM were due to swimming in the Nile and canals and that swimming was the most important exposure and contamination activity. Using multivariate analysis, several sites, study periods, residence groups and mostly canal contacts were significantly correlated with egg-counts. Positive relationships could also be identified using egg-counts with water contact data from preceding study periods, indicating the influence of pre-existing infections, prepatency and seasonality of water contact and transmission. TBM were usually more significantly correlated with egg-counts than frequency and duration of contact. The relevance of the findings for control programmes and the use of school children and the exposure index for water contact studies are discussed.

Changes in the tegumental surface of Schistosoma haematobium during development in the mammalian host.

The development of surface of Schistosoma haematobium in the mammalian host was studied by scanning electron microscopy, beginning with lung stages obtained at 7 days, and at various intervals thereafter to completion of development. The major changes observed were similar to those previously seen in Schistosoma mansoni.

Intestinal capillariasis in Egypt: a case report.

Capillaria philippinensis eggs, larvae, and adults were identified in the stool of a 41-year-old female physician from Cairo, Egypt, who had never traveled abroad. She had eaten local and imported fish. She suffered from borborygmi, abdominal pain, severe diarrhea, vomiting, and loss of weight for greater than 3 months. Treatment with Flubendazole (R17889-Janssen) 200 mg twice daily for 30 days resulted in clinical and parasitological cure.

Evaluation of UNICEF/Arab Republic of Egypt/WHO schistosomiasis Control Project in Beheira Governorate.

We evaluated the UNICEF/Government of Egypt/WHO Schistosomiasis Control project in 2 districts of Beheira Governorate of the Nile Delta during 3 weeks in February 1988. The project, begun in 1983, was focused on reducing prevalence, intensity, and morbidity due to schistosomiasis by providing diagnosis and treatment with praziquantel to schoolchildren. Schools were visited twice. Following the completion of the school surveys, the program was extended into the community. Chemotherapy was delivered by mobile and static teams. The evaluation indicated that, with respect to accuracy of diagnosis, record-keeping, and coverage of targeted populations, project tasks were performed exceedingly well by highly motivated, well-supervised mobile teams. Static teams in rural health centers were less successful in providing diagnosis and chemotherapy to village populations. We resurveyed 6 randomly selected schools to assess the impact of chemotherapy. Overall, the prevalence of Schistosoma mansoni infection was reduced from 60.3% to 24.8% between the first and second surveys (approximately 1 year apart) and was still lower (41.1%) than initial levels up to 3 years after the last treatment with praziquantel. The percentages of those with greater than or equal to 34 S. mansoni eggs/slide using the Kato-Katz technique showed a marked and prolonged decrease (17.1% to 0.3% to 2.2%). The prevalence of S. haematobium infection dropped from 37.6% to 5.5% and was still 9.9% at the time of the evaluation. The percentages of those with greater than or equal to 50 S. haematobium eggs/10 ml urine dropped less dramatically (17% to 4.4% to 11.9%). Mobile teams conducting vigorous chemotherapy programs targeted at schoolchildren can have long-lasting benefits in terms of prevalence and intensity.

Field trial of 1% niclosamide as a topical antipenetrant to Schistosoma mansoni cercariae.

A randomized, double-blind, placebo-controlled field trial of a topical antipenetrant lotion, 1% niclosamide, applied daily to the upper and lower limbs of farmers occupationally exposed to Schistosoma mansoni cercarial-infested water, was conducted in the Nile Delta to assess its safety and efficacy in preventing reinfection. Farmers aged 18-40 years were treated to cure their S. mansoni infections three months prior to the onset of the trial. Subjects were randomly assigned to receive niclosamide or placebo lotion that was self-applied daily for five months. A total of 186 subjects met the inclusion criteria and completed the trial. The exposure to schistosomal-infested water occurred during routine irrigation activities from June to November 1991. Stool specimens were evaluated monthly during and for two months following the lotion application period. The subjects applying the niclosamide lotion were comparable to those applying placebo lotion in age (mean 30 years for both), total water contact (184.5 hr versus 173.8 hr), reported lotion application compliance (88% versus 92%), and reported water contact involving skin exposure other than upper and lower limbs (23% versus 27%). The schistosomal reinfection rate was lower in the niclosamide group (53.3%) compared with the placebo lotion group (71.3%), (P < 0.02). Increased protection might be obtained with total body application for shorter, less intense, water contact exposures.

Hepatic amebiasis: diagnostic counterimmunoelectrophoresis and metronidazole (flagyl) therapy.

In an ongoing study of obscure fevers in Cairo, Egypt which is presently in its 6th year, 12 cases of hepatic amebiasis have been diagnosed. Three were diagnosed during the period 1971-1974. With the introduction of amebic serologic techniques, particularly counterimmunoelectrophoresis, nine additional cases have been diagnosed in 1975-1976. Of 9 patients treated with metronidazole 6 were rapidly cured, 2 had a recurrence of fever necessitating surgical drainage of the abscess, and 1 died suddenly on the 3rd day of therapy.

Use of a partially purified Fasciola gigantica worm antigen in the serological diagnosis of human fascioliasis in Egypt.

Crude extracts of Fasciola gigantica adult worms, when used as an antigen in indirect hemagglutination (IHA) and counterimmunoelectrophoresis (CIEP) tests, detected all independently diagnosed human F. gigantica and F. hepatica infections but cross-reacted with sera of patients with schistosomiasis and amebiasis. Fractionation of this crude worm extract using Sephadex G-200 chromatography demonstrated four major protein peaks. Antigen from the crest and descending portion of peak II (mol. wt. approximately 20 x 10(3)) and all of peak III (mol. wt. approximately 6 x 10(3)) were pooled and used as a source of partially purified antigen. This partially purified fraction, when used in the CIEP test, reacted with sera from patients with fascioliasis but not those from schistosomiasis or amebiasis patients, whether undiluted or concentrated fivefold, but failed to react by IHA with fascioliasis sera. It reacted with undiluted sera from all individuals passing F. gigantica eggs except one, a possibly spurious infection, and with eight of 20 sera from individuals passing F. hepatica eggs, while the remaining 12 sera became positive after fivefold concentration. It also reacted with two sera from individuals passing eggs of both Fasciola species and with five of 11 sera from individuals negative microscopically but positive serologically with the crude antigen.

Salmonella paratyphi A in hamsters concurrently infected with Schistosoma mansoni.

The present work deals with the development of an improved animal model to study the association of salmonellosis and schistosomiasis. The animal chosen was the hamster, Mesocricetus auratus, which can be readily infected with Schistosoma mansoni. Normal hamsters and schistosome-infected hamsters (SIH) were given approximately 2.0 x 10(7) Salmonella paratyphi A intracardially. It was found that S. mansoni infections enhanced and prolonged the growth of S. paratyphi A in hamsters. Animals with dual infections had increased mortality in comparison with those infected with just bacteria or parasite during the 50 days post-bacterial challenge. Further studies showed that in SIH, S. paratyphi A persisted in various organs for up to 8 weeks post infection. In contrast, concurrent Leishmania donovani infections have no effect on S. paratyphi A infections. Significant numbers of bacteria were cultured from well-washed schistosome worms recovered from SIH 6--8 weeks post-bacterial challenge. These findings suggest that a direct physical relationship between the bacteria and worms facilitates the establishment and growth of S. paratyphi A in vivo, and that a deficit in host immune response is not a major factor involved in the enhanced growth of S. paratyphi A.

A longitudinal study of Schistosoma haematobium infection in Qena governorate, Upper Egypt. 1. Initial epidemiological findings.

An epidemiological study was conducted as an initial phase of a longitudinal study on the immunology of Schistosoma haematobium in Upper Egypt. The study area was confined to three villages in Qena governorate, a region endemic solely for S. haematobium. In a cross-sectional survey in two of these villages, the overall prevalence of infection was 28.7% (29.9% at Khozam and 26.9% at El Ayaisha) based on urine examination of the family members in every third household. S. haematobium infection was found in all age groups including infants below 1 year of age. The age distribution of those infected showed the classical rise in the percent infected, reaching a peak of 57-63% in the 11- to 15-year age group followed by a rapid decline and stable low prevalence below 28% in adult years. Males consistently had higher prevalence rates than females at all ages with the profiles of the age prevalence curves strikingly similar. In the two villages, significantly (P less than 0.05) higher infection rates were found in farmers compared to those in other occupations. The overall prevalence of infection in school children (5-16 years old) in the three villages was 61.1% based on the examination of one urine sample. Almost 10% greater prevalence was found when four consecutive daily urines were examined compared to one in the same study group sampled 1 month apart. There was a rapid increase in prevalence with age, reaching a maximum at age 10 with relatively little fluctuation to age 16 years. When comparing the age prevalence data with the intensity of infection expressed as either mean or median age excretion per milliliter urine, it was found that both were parallel and rose sharply from age 5-10 years, but the latter significantly declined several years prior to any perceptible diminution in prevalence.

Epidemiology of cutaneous leishmaniasis at a focus monitored by the multinational force and observers in the northeastern Sinai Desert of Egypt.

A longitudinal epidemiologic study of cutaneous leishmaniasis (CL) transmission was conducted between July 1989 and June 1991 in a 1,200-km2 sector of the northeastern Sinai Desert monitored by the Multinational Force and Observers (MFO), an international peace keeping mission between Egypt and Israel. The occurrence of human cases, sand fly density, rodent collection, and isolations of Leishmania confirmed only one of four surveyed locations as a significant focus of CL transmission. Phlebotomus papatasi, the only anthropophilic sand fly species encountered at this focus, comprised more than 96% of the sand fly population and attained human landing densities exceeding 100 sand flies/person/hr during 1990. Seasonal activity of this species ranged from April to November, with highest densities occurring during the period May-September. A peak promastigote infection rate of 2.4% (13 of 534) was observed in P. papatasi during July 1990. Twelve of the 60 (20%) persons at risk during the six months of intense sand fly activity at this site developed lesions consistent with CL; L. major was isolated from nine (75%) of these cases. Leishmania major infection was acquired by two of 22 (9%) sentinel hamsters used during the same period. More than 97% of the 897 wild rodents trapped at this site were desert gerbil species. Leishmania major was the only Leishmania isolated from human, sand fly, wild rodent (Gerbillus pyramidum), and sentinel hamster infections that originated at site Check point 1-Delta, the focus of CL transmission within jurisdiction of the MFO. The altered ecology of this area, created by construction of a dam, may contribute significantly to the transmission dynamics of CL at this focus.

Evaluation of a twice-a-week application of 1% niclosamide lotion in preventing Schistosoma haematobium reinfection.

A randomized double-blind trial was conducted to assess the efficacy of a twice-a-week application of 1% niclosamide lotion for prevention of Schistosoma haematobium reinfection. Six hundred farmers in Fayoum, Egypt, 18-40 years of age, were treated to cure their S. haematobium infection, then randomly assigned to self-apply niclosamide or placebo lotion to their limbs, neck, and torso. Subjects were exposed to schistosomal-infested water during routine irrigation activities from April to October 1992. Three hundred fifty subjects met the inclusion criteria and completed the trial, 169 (48.3%) in the niclosamide group and 181 (51.7%) in the placebo group. The subjects assigned to the niclosamide-treated group were comparable with those in the placebo group in age (27.2 versus 27.8 years), total water contact (101.9 versus 109.0 hr), lotion application compliance (93.5% versus 90.6%), and avoidance of whole body water contact (94.7% versus 96.7%). The reinfection rate with S. haematobium was 30.8% in the niclosamide-treated group and 28.2% in the placebo group. Niclosamide lotion applied to the limbs and trunk twice a week failed to prevent S. haematobium reinfection.

Etiology of acute diarrhea among United States Embassy personnel and dependents in Cairo, Egypt.

The purpose of this study was to identify the enteropathogens causing acute diarrheal disease in Americans living in the North Africa/Middle East region during a 34-month period from February 12, 1985 to December 30, 1987 to guide preventive and therapeutic measures. Stool specimens were examined and an epidemiologic questionnaire was administered to patients with acute diarrhea at the Outpatient Health Unit of the United States Embassy in Cairo, Egypt. The subjects consisted of 126 American employees and dependents of the U. S. Embassy in Cairo, Egypt with diarrhea of less than two-weeks duration. Subjects received routine medical care administered by the U.S. Embassy Medical staff. A possible etiologic agent was detected in 41% of the subjects. Enteroadherent Escherichia coli was the most commonly isolated enteropathogen. A high degree of antimicrobial resistance was noted among the bacterial isolates, but all were susceptible to the quinolone antibiotics. Episodes of acute diarrhea occurring among American expatriates in Cairo, Egypt were primarily of bacterial etiology, but only a small portion were caused by the bacterial pathogens routinely identified in a standard clinical bacteriology laboratory. Most of the diarrheal episodes were due to noninvasive enteroadherent E. coli that may cause prolonged disease requiring antimicrobial therapy.

Biochemical characterisation of human isolates of Blastocystis hominis.

SDS-PAGE and iso-enzyme analysis of 11 human isolates of Blastocystis hominis revealed at least two variants with different polypeptide patterns and two zymodemes, respectively. This is the first iso-enzyme and the second protein analysis to indicate strain differences in B. hominis.

A purified Fasciola gigantica worm antigen for the serodiagnosis of human fascioliasis.

Partially purified Fasciola gigantica worm antigens were evaluated in an enzyme-linked immunosorbent assay (ELISA) for the specific serological diagnosis of fascioliasis. The diagnostic potential of 10 antigen fractions derived from gel-filtration peaks (II & III) were evaluated individually or in combination against a panel of admission sera obtained from 50 patients subsequently diagnosed as having a variety of systemic parasitic diseases, and from 10 healthy volunteers with no recent history of parasitic infections. Fractions 2 and 10 were highly specific for Fasciola infection and failed to react with sera from any patient with other parasitic diseases or from controls. All other fractions exhibited reactivity with the majority of sera from the fascioliasis patients, but also with some sera from patients infected with other parasites. Based on these results, the ELISA, as outlined here, should be considered as a rapid and specific technique for the diagnosis of fascioliasis and also as an epidemiological surveillance technique in areas endemic for F. gigantica infection.

Further characterization of Leishmania isolates from children with visceral infection in Alexandria area, Egypt.

Two visceral Leishmania isolates from children (aged 1 1/2 and 4 years) living in El Agamy area, Alexandria, Egypt, were compared with 5 marker strains, and 2 other human isolates from Sinai and Sudan, identified on clinical and geographical grounds as cutaneous and visceral leishmaniasis respectively. Isoenzyme variations were assessed on the basis of their electrophoretic profiles on cellulose acetate membranes. The enzymes studied were glucose 6-phosphate dehydrogenase E.C.1.1.1.49, phosphoglucomutase E.C.2.7.5.1, 6-phosphogluconate dehydrogenase E.C.1.1.1.44 (6-PGD), glucose phosphate isomerase E.C.5.3.1.9, malate dehydrogenase E.C.1.1.1.37, mannose phosphate isomerase E.C.5.3.1.8 and nucleoside hydrolase E.C.3.2.2.2. The last 4 enzymes could differentiate between cutaneous and visceral strains. The Alexandria strains proved to belong to the L. donovani complex; however, their 6-PGD pattern was identical to that of L. infantum, which was different from that of the L. donovani marker strain.

Early diagnosis of human fascioliasis by the detection of copro-antigens using counterimmunoelectrophoresis.

We have reported the use of partially purified Fasciola gigantica worm antigens (peaks II and III separated by Sephadex G-200) in counterimmunoelectrophoresis (CIEP) for the specific and early detection of antibodies in sera of fascioliasis patients. In the present study, we report the use of hyperimmune serum from rabbits immunized with these partially purified worm antigens in CIEP for the detection of parasite antigens in saline extracts of patients' stools. This test was conducted on stool specimens from 144 patients with systemic or intestinal parasitic infections, 5 from persons with spurious Fasciola infections, and 10 from healthy negative controls. All saline extracts from fascioliasis patients developed 2-5 precipitin bands. No precipitin band developed with stool extracts of patients with spurious Fasciola infection or other parasitic infections, or from negative controls. This assay proved to be simple, rapid, sensitive, and specific for the diagnosis of early as well as established fascioliasis infections.

Water contact behavior and schistosomiasis in an upper Egyptian village.

Preliminary findings of a study of the role of microspatial behavior and local ecological circumstances in the persistence of Schistosoma haematobium infection in El Ayaisha village, Upper Egypt, are presented. Twelve types of water contact activities were studied in three cohorts of 274,324 and 392 male students aged 5-16 during a 2-year period. Swimming and playing resulted in more frequent and intensive contact with potentially infective water and in more pollution of snail habitats with schistosome eggs than any other type of activity. Irrigation was probably not a major cause of S. haematobium infection in schoolboys and drinking water and fishing carried the smallest risk for this age group. Mapping and discriminate analysis of infection and transmission indicators revealed spatial associations between water contact, schistosome transmission and infection among the various age groups. The highest egg excretion rates in individuals and the highest prevalence rates were noted in the neighborhoods nearest to the canals. Water contact and contamination of water by the heavily infected school age boys is seasonally concentrated during the summer, when intermediate host snails and infective cercariae are also most common in the water. Frequency, type and duration of water contact change with age together with types of water bodies used, causing corresponding changes in exposure risk. Nevertheless, other factors, including acquired immunity, preexisting infections, chemotherapy and the effect of the study on the normal water contact behavior of the study population must also be evaluated. Contact with the Nile and the canals by the general nonschool population of El Ayaisha was studied to verify the observations among the schoolboys and to study socially linked activities and the transmission potential of the various transmission sites. Results are evaluated in regard to the feasibility of various schistosomiasis control measures in El Ayaisha.

Feeding patterns of Phlebotomus papatasi and Phlebotomus langeroni (Diptera: Psychodidae) in El Agamy, Egypt.

Blood meals from 602 Phlebotomus papatasi (Scopoli) and 49 Phlebotomus langeroni Nitzulescu were collected in El Agamy, Egypt, and were identified using counterimmunoelectrophoresis. Blood meals were tested against specific antisera of eight vertebrate hosts (human, cat, dog, rat, sheep, goat, general avian, and general bovine). Of 597 P. papatasi collected indoors, 594 contained human blood and three had mixed blood meals (human-dog, human-rat, and human-avian). Four of five P. papatasi collected outdoors contained human blood and one contained avian blood. All 39 P. langeroni collected indoors had fed on humans. Six of 10 outdoor-collected P. langeroni had fed on human blood, 2 on dog, 1 on cat, and 1 on rat blood. Both P. papatasi and P. langeroni feed predominantly on humans in El Agamy, Egypt. The documented feeding on humans and dogs by P. langeroni supports the role of this species as the primary vector of visceral leishmaniasis at the El Agamy focus.

Worm development in hamsters infected with unisex and cross-mated Schistosoma mansoni and Schistosoma haematobium.

Schistosoma mansoni and Schistosoma haematobium coexist in Egypt and in other areas in Africa, and people frequently are infected with parasites of both species. The effects of the interactions between worms of both sexes of the 2 species on development and egg laying were evaluated in vivo by infecting hamsters with cercariae from Biomphalaria alexandrina and Bulinus truncatus snails infected with single miracidia. In hamsters with unisex infections, male worms of both species were small. Schistosoma mansoni females were stunted and partially mature but did not contain eggs. Schistosoma haematobium females, though stunted, sometimes contained and laid small eggs, which were deposited in the liver, but few of which contained motile embryos. This suggests that unisexual infection with S. haematobium female worms produces a risk for liver damage due to egg deposition in tissues. Both S. mansoni and S. haematobium females that mated with males of the heterologous species were significantly larger than females from unisexual infections; they were sexually mature and possessed eggs in the uterus. The eggs in the liver homogenates of cross-specific infected hamsters contained fully developed miracidia that hatched in filtered pond water.

Identification of Trichinella isolates from naturally infected stray dogs in Egypt.

Larvae of Trichinella species recovered from the diaphragms of 2 stray dogs killed during a governmental antirabies campaign in Cairo, Egypt, were fed to white mice for production of adult worms and larvae for morphological and isoenzyme studies. Comparisons were made with reference species of Trichinella spiralis, Trichinella nelsoni, Trichinella nativa, and Trichinella pseudospiralis. Results indicated that the 2 Trichinella specimens from the dogs were morphologically and biochemically identical with T. spiralis.