ABSTRACT
The epidemiological indices of Schistosoma mansoni for three communities in Ethiopia; Jigga (Northwest); Metahara sugar estate (Southeast) and Lake Zway (Central); each representing the three major transmission ecologies in the country; the stream; irrigation scheme and lake; respectively were studied and compared. A total of 2897 people (913; 1614 and 370 from the stream; irrigation scheme and lake; respectively) was examined for S. mansoni ova by the Kato's smear method. The highest human prevalence (58 per cent) and intensity of infection (geometric mean of 450 EPG) were recorded for the lake ecology; whereas the irrigation scheme and stream showed moderate (218 EPG) and light (172 EPG) intensities of infection; despite fairly high disease prevalences of 20 per cent and 41 per cent respectively. Age-specific analysis of prevalence; intensity of infection and relative index of potential contamination (RIPC) indicated that children in their second decade of life to be most responsible. Nevertheless; the decline of all indices with increasing age was less obvious in the lake area than others. The disparity between prevalence and intensity of infection and their implication in disease control tactics are discussed