EPIDEMIOLOGY OF SCHISTOSOMA-MANSONI INFECTION IN A RECENTLY EXPOSED COMMUNITY IN NORTHERN SENEGAL

The epidemiology of Schistosoma mansoni infection was investigated in Ndombo, a village in the epicenter of a very recent outbreak of schist osomiasis in northern Senegal. Repeated fecal egg counts and antigen d etection in urine and serum were carried out in a random population sa mple (n = 422). Eggs were found in 91% of the subjects, with 41% excre ting > 1,000 eggs per gram of feces (epg) (mean egg load of 646 epg). The prevalence was almost 100% in groups greater than five years of ag e. In spite of the supposed absence of acquired immunity, intensities of infection decreased strongly in adults. Antigen detection confirmed the high prevalence and intensity of infection and the age-related di stribution of worm loads. The emergence of this new focus is probably due to the ecologic impact of newly built dams and the extension of ir rigation projects in the Senegal basin.