Immunity and morbidity in Schistosoma mansoni infection: quantitative aspects.

Immunity to Schistosoma mansoni infection in humans can be studied most easily by monitoring serially the intensity of reinfection that occurs among individuals who have undergone chemotherapeutic cure, and whose levels of exposure to contaminated water is subsequently observed. Parallel studies can then be made of those immune responses that are correlated with an observed resistance to reinfection. This paper describes some of the difficulties associated with this approach, with particular reference to the authors' own studies in Kenya, and highlights a possible role of immunoglobulin E antibodies against adult worm antigens in mediating immunity.