Parameters associated with Schistosoma haematobium infection before and after chemotherapy in school children from two villages in the Coast provinceof Kenya

We evaluated the impact of praziquantel therapy (40 mg/kg body weight) on i ndicators of infection with Schistosoma haematobium by following a cohort o f infected children from schools located 12 km apart in the Coast province of Kenya, at 0, 2, 1, 6, 12 and 18 months after treatment. Within this peri od, measurements of infection parameters pertaining to egg counts and haema turia (micro-, macro- and history) were evaluated at all time points. The i nitial prevalence of 100% dropped significantly 8 weeks alter treatment wit h a similar trend in the intensity of infection. Microhaematuria followed t he same trend as observed for egg counts while macrohaematuria remained low after treatment. Reinfection following successful therapy differed signifi cantly between schools; in one school the children were reinfected immediat ely while those in the other remained uninfected despite similar starting p revalences, intensities of infection and cure rates. Transmission between t he 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 af ter allowing for pretreatment infection level, age and sex, area (school) r emained a highly significant predictor.