Manson's schistosomiasis in Brazil: 11-year evaluation of successful disease control with oxamniquine.

This prospective study has shown that oxamniquine treatment controlled endemic schistosomiasis mansoni in a defined rural population in Castro Alves, north-east Brazil. Data before and after treatment spanning 11 years were collected for a cohort of 191 residents. Before treatment (1974-77), the cohort was heavily infected and the prevalence of associated hepatomegaly (greater than 86%) and splenomegaly (greater than 17%) was stable. The cohort was treated when oxamniquine became available in 1977; during the next 8 years, over 80% received further treatments from the Brazilian programme for the control of schistosomiasis. With treatment, the incidence of splenomegaly fell (10% to 2%) and the splenomegaly regression rate increased (43% to 91%). Declining disease rates were coincident with substantial falls in the prevalence and intensity of Schistosoma mansoni infections. The final prevalence rates for hepatomegaly (31%) and splenomegaly (3%) in Castro Alves approached the corresponding rates of 10% and 1% in a comparable uninfected control population.