CROSS-SECTIONAL AND EVOLUTIVE STUDIES OF SCHISTOSOMIASIS-MANSONI IN UNTREATED AND MASS TREATED ENDEMIC AREAS IN THE SOUTHEAST AND NORTHEASTOF BRAZIL

Cross-sectional and evolutive studies on schistosomiasis mansoni were carried out before and after mass treatment in the endemic areas of Ca pitao Andrade and Padre Paraiso, state of Minas Gerais, Riachuelo, sta te of Sergipe, Alhandra, state of Paraiba, and Alianca, Alegre and Cor oata, lowland of the state of Maranhao, Brazil, in the last eighteen y ears. The studies included clinical and fecal examination by the Kato- Katz quantitative technique, skin test for Schistosoma mansoni infecti on, evaluation of man-water contact and other epidemiological investig ations such as infection rate and dynamic of the snail population. Res ults showed: (1) Higher prevalence of S. mansoni infection, greater eg g load elimination and higher and earlier morbidity of the chronic for ms of the disease in the southeast areas of Capitao Andrade and Padre Paraiso; (2) The incidence of hepatosplenic form is higher in some fam ily clusters, in whites and mulattos in all the endemic areas but deve lop earlier in the southeast; (3) The prevalence and morbity of schist osomiasis are decreasing both in the mass treated northeast and in the untreated southeast areas; (4) The mass treatment reduces rapidily th e prevalence of the infection and the morbidity of the disease but can not control it because of the frequent reinfections due to the intens ity of man-water contact.