Effect of repeated targeted mass treatment with praziquantel on the prevalence, intensity of infection and morbidity due to Schistosoma intercalatum in an urban community in equatorial Guinea.

A longitudinal community-based study was carried out in order to evaluate the impact of repeated selective population chemotherapy with praziquantel on the epidemiology of an urban focus of Schistosoma intercalatum in the city of Bata, capital of the Continental Region of Equatorial Guinea. Three surveys were undertaken in January of 1988, 1989 and 1990, determining parasitological prevalence, intensity of infection and morbidity and applying repeated targeted mass treatment. One dose of praziquantel (40 mg/kg body weight) was given one week after treatment with mebendazole (100 mg every 12 hours for 3 days). A reduction of the overall prevalence by S. intercalatum of 69.9% and 79.3% in the first and second year respectively was found. Persons showing high parasite burden suffered a reduction of 95.7%. The cure rate (no more eggs in stool) was between 90% and 98.9%. A significant decrease of signs and symptoms was observed. No important side effects were detected. This study shows the positive action of praziquantel in reducing prevalence, intensity of infection and morbidity due to S. intercalatum, above all in the case of a high human population participation response. Cure rates obtained being similar to the ones observed using the same drug in Schistosoma mansoni and Schistosoma haematobium.