The epidemiology of schistosomiasis is changing because treatment of c
hronically infected individuals is often followed by reinfection. As a
major goal of schistosomiasis control is the reduction of morbidity,
direct assessment of disease is essential because infection status is
a relatively poor indication of morbidity. Introduction of ultrasonogr
aphy to the study of schistosomiasis and the increased appreciation of
the effects fo schistosomiasis on growth and development in children
have greatly enhanced our understanding of schistosome-induced morbidi
ty in endemic communities. Peter Wiest here reviews the changes in the
assessment of schistosomiasis-induced morbidity.