EFFECT OF HUMAN IMMIGRATION ON THE AGE DISTRIBUTION OF SCHISTOSOME INFECTIONS IN SIAVONGA COMMUNITY, LAKE KARIBA, ZAMBIA

A study on the distribution of schistosomiasis in the community at Sia vonga revealed Schistosoma haematobium infection in 35.5% of 338 subje cts and a geometric mean egg count (GMEC) and (S.D.) of 13.7 (7.2) egg s/10 ml urine. The prevalence of S. mansoni infection among 323 subjec ts was 60.1%, with a GMEC of 336.8 (4.8) eggs/g stool. Among the infec ted, 69.5% carried both schistosome species. Although prevalence of in fection with either species was highest in those aged 10-14 years, hig h prevalences of infection were found in older age groups and egg inte nsities were uniformly distributed throughout all age-groups. The obse rved diversion from the typically age-dependent distribution of schist osome infections probably reflects exposure to infection relatively la te in life, as the result of immigration from non-endemic areas.