Eight years of targeted mass treatment of Schistosoma mansoni infection in Maniema, Zaire.

Eight to ten years of follow-up the impact of targeted mass treatment, given to heavily infected people in Maniema's tin-mining district in Zaire, showed that the prevalence and intensity of infection were almost the same as before control. The high frequence of hepatomegaly, and to a lesser extent of splenomegaly, which were shown to be related to schistosome infection, however, have disappeared. For the evaluation of the impact of control, other parameters than egg counts only need further development.