Praziquantel chemotherapy has been the focus of the Schistosomiasis Control Program in Brazil for the past two
decades. Nevertheless, information on the impact of selective chemotherapy against
Schistosoma mansoni
infection
under the conditions confronted by the health teams in endemic municipalities remains scarce. This paper compares
the spatial pattern of infection before and after treatment with either a 40 mg/kg or 60 mg/kg dose of praziquantel by
determining the intensity of spatial cluster among patients at 180 and 360 days after treatment. The spatial-temporal
distribution of egg-positive patients was analysed in a Geographic Information System using the kernel smoothing
technique. While all patients became egg-negative after 21 days, 17.9% and 30.9% reverted to an egg-positive
condition after 180 and 360 days, respectively. Both the prevalence and intensity of infection after treatment were
significantly lower in the 60 mg/kg than in the 40 mg/kg treatment group. The higher intensity of the kernel in the 40 mg/kg
group compared to the 60 mg/kg group, at both 180 and 360 days, ref lects the higher number of reverted cases in the
lower dose group. Auxiliary, preventive measures to control transmission should be integrated with chemotherapy to achieve a more enduring impact.
