Natural history of papillary lesions of the urinary bladder in schistosomiasis.
Variable epithelial hyperplasia was observed in urinary bladder of nine capuchin monkeys (Cebus apella) when examined at cystotomy 94 to 164 weeks after infection with Schistosoma haematobium. These hosts were followed for 24 to 136 weeks postcystotomy to determine the status of bladder lesions in relation to duration of infection and to ascertain whether lesion samples removed at cystotomy reestablished themselves in autologous and heterologous transfers. There was involution of urothelial hyperplasia in eight of nine animals and no evidence for establishment of transplanted bladder lesions. (+info)
Urinary schistosomiasis among schoolchildren in Ibadan, an urban community in south-western Nigeria.
The current status of urinary schistosomiasis was assessed in Ibadan, an urban community in south-western Nigeria. Of 1331 children examined for eggs of S. haematobium in their urine, 17.4% were infected. Prevalence in postprimary schoolchildren was significantly (P < 0.01) higher (22.4%) than in primary schoolchildren (12.0%). Intensity of infection based on geometric mean egg count per 10 ml of urine was also higher in postprimary (36.7 eggs/10 ml urine) than primary pupils (29.9 eggs/10 ml urine). Boys had a significantly (P < 0.01) higher infection rate (24.1%) than girls (8.5%), and the intensity of infection was also higher (P < 0.01) in males (39.0 eggs/10 ml urine) than in females (22.1 eggs/10 ml urine). The overall geometric mean intensity of infection was highest (38.8 eggs/10 ml urine) in the 11-15 years age group. 42% of infected children excreted > 50 eggs/10 ml urine. 2.2% excreted S. mansoni eggs in urine. Water contact activities were more frequent (P < 0. 01) in males (31.8%) than females (38.2%). Nine species of snails were encountered, with B. (p) globosus being the the most abundant and widespread. These results show that urinary schistosomiasis is still being actively being transmitted in Ibadan. (+info)
Emergence of Schistosoma mansoni infection in upper Egypt: the Giza governorate.
We found an unexpectedly high prevalence of Schistosoma mansoni in a village in the Upper Egyptian governorate of Giza. Historically, S. mansoni is endemic in the northern Egyptian Nile Delta rather than in the southern Upper Egypt. This observation was made during an evaluation of a rural health care schistosomiasis surveillance program using a cross sectional survey for S. haematobium and S. mansoni in the village of El-Gezira El-Shakra El-Saf district in the Upper Egypt Giza Governorate. A 10% systematic random sample of households of the village was chosen. All persons in the selected houses were invited to submit urine and stool samples. All students from a primary school were also included in the study. Urine was screened by a polycarbonate filtration method and stool was examined using modified Kato-Katz technique. The prevalence of S. mansoni in the population sample and in the school children was 33.7% and 57.7%, respectively, whereas the prevalence of S. haematobium infection in the population sample and the school children was 7.4% and 10.6%, respectively. The prevalence of infection was highest in the younger age groups, and males were infected more than females. Review of Ministry of Health records showed that both species of vector snails, Bulinus truncatus and Biomphalaria alexandrina, were present from 1991 to 1995, and that B. alexandrina was more abundant than B. truncatus in the canals surrounding this village. The unexpected high prevalence of S. mansoni in this village indicates an urgent need to include training programs for S. mansoni surveillance in the primary health care facilities of Giza and to educate villagers to request examinations for S. mansoni as well as for S. haematobium infection. (+info)
Helminth- and Bacillus Calmette-Guerin-induced immunity in children sensitized in utero to filariasis and schistosomiasis.
Infants and children are routinely vaccinated with bacillus Calmette-Guerin (BCG) in areas of the world where worm infections are common. Because maternal helminth infection during pregnancy can sensitize the developing fetus, we studied whether this prenatal immunity persists in childhood and modifies the immune response to BCG. Children and newborns living in rural Kenya, where BCG is administered at birth and filariasis and schistosomiasis are endemic, were examined. T cells from 2- to 10-year-old children of mothers without filariasis or schistosomiasis produced 10-fold more IFN-gamma in response to mycobacterial purified protein derivative than children of helminth-infected mothers (p < 0.01). This relationship was restricted to purified protein derivative because maternal infection status did not correlate with filarial Ag-driven IL-2, IFN-gamma, IL-4, or IL-5 responses by children. Prospective studies initiated at birth showed that helminth-specific T cell immunity acquired in utero is maintained until at least 10-14 mo of age in the absence of infection with either Wuchereria bancrofti or Schistosoma haematobium. Purified protein derivative-driven T cell IFN-gamma production evaluated 10-14 mo after BCG vaccination was 26-fold higher for infants who were not sensitized to filariae or schistosomes in utero relative to subjects who experienced prenatal sensitization (p < 0.01). These data indicate that helminth-specific immune responses acquired during gestation persist into childhood and that this prenatal sensitization biases T cell immunity induced by BCG vaccination away from type 1 IFN-gamma responses associated with protection against mycobacterial infection. (+info)
Schistosoma TOR (trispanning orphan receptor), a novel, antigenic surface receptor of the blood-dwelling, Schistosoma parasite.
Sh-TOR is a novel, putative three transmembrane domain receptor of Schistosoma haematobium, which has no extensive homology to any other known protein. The 0.86 kb open reading frame was found to encode a novel protein, 286 amino acids long and of 32 kDa. It was shown that Sh-TOR can be phosphorylated on tyrosine and the protein sequence reveals a long cytoplasmic tail with several consensus phosphorylation sites for enzymes which characteristically associate with membrane receptors. The proposed topology of Sh-TOR, based on antibody recognition of transfected Sh-TOR, predicts that the amino terminus is extracellular and the carboxyl terminus intracellular. Sh-TOR is a non-glycosylated protein found in the surface tegumental plasma membrane, and tegumental surface pits of adult schistosomes. The 1.35 kb transcript was most highly expressed in the larval stage, which is more susceptible to immune attack. A TOR homologue from Schistosoma mansoni is also described. A homologue from Trypanosoma cruzi, another human parasite was also isolated, but not from the free-living nematode Caenorhabditis elegans. Recombinant Sh-TOR is specifically recognised by a passively protective serum, from baboons vaccinated with irradiated Schistosoma parasite. Together with its surface location, this means that Sh-TOR is also a potential vaccine candidate molecule. (+info)
Parameters associated with Schistosoma haematobium infection before and after chemotherapy in school children from two villages in the coast province of Kenya.
We evaluated the impact of praziquantel therapy (40 mg/kg body weight) on indicators of infection with Schistosoma haematobium by following a cohort of infected children from schools located 12 km apart in the Coast province of Kenya, at 0, 2, 4, 6, 12 and 18 months after treatment. Within this period, measurements of infection parameters pertaining to egg counts and haematuria (micro-, macro- and history) were evaluated at all time points. The initial prevalence of 100% dropped significantly 8 weeks after treatment with a similar trend in the intensity of infection. Microhaematuria followed the same trend as observed for egg counts while macrohaematuria remained low after treatment. Reinfection following successful therapy differed significantly between schools; in one school the children were reinfected immediately while those in the other remained uninfected despite similar starting prevalences, intensities of infection and cure rates. Transmission between the two areas looked homogeneous before treatment but when both groups were treated, contrasting transmission patterns became evident. In a regression model we evaluated factors that might be associated with reinfection, and after allowing for pretreatment infection level, age and sex, area (school) remained a highly significant predictor. (+info)
Application of immunodiagnostic assays: detection of antibodies and circulating antigens in human schistosomiasis and correlation with clinical findings.
In an initial cross-sectional survey, serum, urine, and stool samples were collected from 370 participants representing about 10% of the population (n = 4,438) in Behbeet village, 50 km south of Cairo, Egypt, an area well known to be endemic solely for Schistosoma haematobium. Diagnosis was approached in two parallel ways. The first approach, which simulated actual conditions in many endemic areas in Egypt, was based on physical examination and urine and stool microscopic analysis. The second approach was based on two advanced immunodiagnostic assay systems. One system detected antibodies to species-specific microsomal antigens, the other detected circulating schistosomal antigens. Microsomal antigens from S. haematobium and S. mansoni were used to detect antibodies in the Falcon assay screening test (FAST)-ELISA and the enzyme-linked immunoelectrotransfer blot (EITB). Circulating anodic antigen (CAA) and circulating cathodic antigen (CCA) were quantified in serum and urine samples in a sandwich ELISA using monoclonal antibodies. Parasitologically, the prevalence of S. haematobium was 7.01% in females and 25.82% in males, giving an overall prevalence of 15.8%. The combination of urine CCA and serum CAA for detecting circulating antigens and the combination of the S. haematobium adult worm microsomal antigens (HAMA) FAST-ELISA and the HAMA EITB for detecting antibodies significantly improved the sensitivity of detecting S. haematobium circulating antigens and antibodies. Also, including a medical examination as an integral part of field studies and correlating immunodiagnostic results with other clinical and investigational data allowed us to calculate an accurate estimation of S. haematobium prevalence in this area of low endemicity. (+info)
Urine circulating soluble egg antigen in relation to egg counts, hematuria, and urinary tract pathology before and after treatment in children infected with Schistosoma haematobium in Kenya.
A cohort of 117 school children infected with Schistosoma haematobium was followed-up after therapy with praziquantel (0, 2, 4, 6, 12, and 18 months) and various infection and morbidity parameters (egg counts, hematuria, soluble egg antigen [SEA] in urine, and ultrasonography-detectable pathology) were quantified. At the onset of the study, 97% of the children were positive for S. haematobium with a geometric mean egg count of 45.7 eggs/10 ml of urine. Eighty-one percent of the children were positive for SEA in urine with a geometric mean SEA concentration of 218.8 ng/ml of urine. Ninety-two percent and 56% of the children were microhematuria positive and macrohematuria positive, respectively. Two months after treatment, all infection and morbidity indicators had significantly decreased. Reinfection after treatment as determined by detection of eggs in urine was observed by four months post-treatment while the other parameters remained low. The clearance of SEA was slower than that of egg counts while pathology resolved at an even slower pace. Levels of SEA and egg output showed similar correlations with ultrasound detectable pathology; these correlations were better than the correlation between hematuria and pathology. (+info)