IMMUNITY AND MORBIDITY IN HUMAN SCHISTOSOMIASIS-MANSONI

This paper reviews the results of a longitudinal, multidisciplinary st udy on schistosomiasis mansoni that has been in progress in Machakos D istrict, Kenya, since 1980. Different methods of delivering chemothera py have been compared in a medium scale operational control programme. It is concluded that treatment only of infected children is an effect ive and feasible means of control, the frequency of treatment dependin g on the severity of disease. Within the framework of this programme, detailed studies have been undertaken of immunity to reinfection after treatment and of the reasons for differences in observed morbidity be tween different areas. An apparent resistance to reinfection, especial ly in older individuals, may be attributable to the protective effect of IgE antibodies against adult worm antigens. Various factors other t han intensity of infection may contribute severe morbidity, including parasite strain differences, interactions with other infections, nutri tional status, and abnormalities in the regulation of pathogenic immun e responses to egg antigens.