Long-term echographic monitoring of children with schistosomiasis haematobia after praziquantel

During a Schistosoma haematobium morbidity control program in Niger, we con ducted a survey to describe the resolution of lesions after treatment with praziquantel, to determine reinfection rates and to define retreatment sche dules. 114 schoolchildren (7-15 years old) living in an hyperendemic villag e underwent 10 successive examinations over 34 months following an initial evaluation and the administration of 40 mg/kg of praziquantel. All children , whether apparently infected with S. haematobium or not, were treated. Egg output, microhaematuria, visual aspect of urine and abnormalities of the u rinary tract by ultrasound were assessed. The initial prevalence of infecti on was 74.5%. Reinfection began 5 months after treatment and the final prev alence was 47.1%. Bladder abnormalities decreased rapidly but incompletely, probably due to reinfestation (initial prevalence: 89.5%). Their prevalenc e increased 8 months after treatment to 72.4% at month 34. Dilatations of t he upper urinary tract regressed more slowly but constantly until the end o f the study (initial prevalence: 43%; 4.6% at month 34). Three years after treatment, despite reinfection, the general morbidity level (prevalence and severity of lesions) was lower than at baseline in our cohort, which would suggest the advantage of a long interval between mass treatments in the ep idemiological context of our survey.