Schistosoma mansoni infection in a new settlement in Metekel district, north-western Ethiopia: morbidity and side effects of treatment with praziquantel in relation to intensity of infection

A study of morbidity and side effects of treatment with praziquantel in relation to intensity of infection with Schistosoma mansoni was conducted in 406 infected individuals from a newly-settled village in Metekel, north-western Ethiopia. Each subject was submitted to a standardized medical history and abdominal palpation. The frequencies of hepatomegaly and splenomegaly were low, 2% and 3%, respectively. A positive association was found between egg load and a history of blood in the stool. Interviews on side effects were conducted on the day following treatment with praziquantel (40 mg/kg body weight). Positive correlations with egg load were found for several side effects, including abdominal pain, diarrhoea, headache, back pain, and vomiting. Unusual side effects involving swelling of various parts of the body confirm 2 previous reports from a different region in Ethiopia and should be investigated further.     

Sonographic studies of schoolchildren in a village endemic for Schistosoma mansoni

Parasitological, clinical, and sonographic examinations were performed on 309 school children in a village endemic for schistosomiasis mansoni. Data from the 255 denying treatment within the previous 2 years were analysed separately. On a single Kato examination 42% were uninfected; the remainder had light (26%), moderate (21%), or heavy (11%) infections with Schistosoma mansoni. Hepatomegaly (53%) and palpable spleens (35%) were common but clinical and parasitological findings often were unrelated. Abdominal sonography also demonstrated a high frequency of hepatomegaly (82%) and splenomegaly (49%). Sonographically determined liver span and spleen size correlated with the egg count. Sonographic lesions of periportal fibrosis of schistosomiasis mansoni with thickening of portal tracts and portal vein walls were frequently present and more common in infected than in uninfected children, and were correlated with the number of S. mansoni ova in the stool. Ultrasonographically detected periportal fibrosis was a reliable measurement of the prevalence and morbidity of schistosomiasis mansoni in this population, and provided very useful information, even when the parasitological and clinical findings were equivocal.     

Oral fluids for the immunodiagnosis of Schistosoma mansoni infection

Saliva and oral transudate were evaluated for their potential as human specimens in the detection of IgG antibodies against soluble Schistosoma mansoni egg antigen (SEA). Preliminary laboratory testing of 49 subjects, 37 with parasitological proven infection and 12 negative controls, displayed 100% sensitivity in ELISA using serum and oral transudate and 94.6% using saliva. The specificity of the ELISA with serum was 100% versus 91.7% with both oral fluids. Significant Spearman rank correlations of anti-SEA IgG levels with egg counts were observed for serum, oral transudate and saliva (P < 0.05). The sensitivity of dot-ELISA was 100% for serum, 89% for transudate and 81% for saliva, and specificity was 100% for all 3 samples. The immunodiagnostic value of ELISA for the detection of anti-SEA IgG antibodies in oral transudate was further evaluated in 197 individuals from an endemic area of Brazil. The ELISA using serum and oral transudate showed sensitivities of 98.8% and 100% respectively and specificities of 67.8% and 64.3% respectively. Use of oral fluids for the diagnosis of S. mansoni infection was equivalent to sera with respect to test efficacy, offering an alternative to blood collection.     

Stability of faecal egg excretion in Schistosoma mansoni infection

Stability of Schistosoma mansoni egg excretion was studied in 23 residents of a rural endemic area in North-east Brazil where the over-all prevalence rate was 87% and the peak geometric mean egg excretion was 308 eggs/ml (Bell method) in the 10 to 14-year-old age group. Stool examinations by the Kato method were performed for three to four consecutive days each month for three consecutive months. Both raw and transformed data showed significant stability of S. mansoni egg excretion from day to day and month to month in this population. A single Kato examination detected 68% of individuals who were excreting more than 400 eggs per gramme. Although S. mansoni egg excretion is stable over time, identifying individuals with high egg excretion in endemic populations requires sensitive quantitative methods.     

Comparison of ELISA,radioimmunoassay and stool examination for Schistosoma mansoni infection

A comparison was made of the sensitivity and specificity of four diagnostic tests for Schistosoma mansoni infection in a community of 516 untreated persons in St. Lucia, West Indies. Prevalence of infection as obtained by: (i) the Bell filtration technique was 44·4% (one filter) and 63·2% (three filters); (ii) the Kato thick smear, 60·2%; (iii) by radioimmunoassay (RIA), 73·3%; and (iv) enzyme-immunoassay (ELISA) 70·9%. The age distribution of persons serologically positive but parasitologically negative showed these to be mostly children and persons 40 years old and over. By means of a statistical test due to Cochrane, it was concluded that there was no evidence to indicate a difference between paired serological tests and paired parasitological tests in their diagnostic capability. There was a very significant difference between the Bell technique and the other three tests. The ELISA emerged as a less satisfactory test than the RIA or the Kato thick smear. The levels of sensitivity and specificity of each test were measured by Armitage's “J” index. The reliability of the Bell filtration technique was 64%, of the ELISA 68%, of the RIA 78% and of the Kato 85%.     

The effect of multiple doses of antimonials in Schistosoma mansoni infection

The treatment of bilharziasis with antimonials has been carried out in the past in a rather arbitrary manner, dosage levels and schedules varying widely and being based on little valid experimental evidence. The author has therefore attempted to determine the optimum dosage intervals with tartar emetic for cure of mice experimentally infected with Schistosoma mansoni.     

Kidney biopsy in the hepatosplenic form of infection with Schistosoma mansoni in man

A study of early glomerular lesions was made in 8 patients infected with Schistosoma mansoni but having no clinical evidence of renal disease. Electron-microscopy of renal biopsies showed the presence of electron-dense deposits in basement membranes and of laminated bodies near the mesangial cells. Immunofluorescence showed that the deposits corresponded to IgG in 8 cases and to IgM in 2 cases. These lesions are comparable with those found in the kidneys of patients with cirrhosis of the liver.     

Chemotherapeutic studies on experimental Schistosoma mansoni infection of Mastomys natalensis

Comparative chemotherapeutic studies on various well known or newly developed schistosomicidal agents have been carried out in Mastomys natalensis experimentally infected with Schistosoma mansoni. Hycanthone, lucanthone, niridazole, Mirasan, the experimental compounds HOE S616, HOE S683, HOE S688, and HOE S201, tartar emetic, stibophen, and stibocaptate acid have shown marked activity when administered in standard daily dosages for 5 consecutive days. Dehydroemetine and bis (p-rosaniline pamoate) proved to be ineffective. The mode of action and the dose—activity relationship of hycanthone methanesulfonate are discussed and compared with the results found for other antimonial and non-antimonial substances.