The prevalence and distribution of schistosomiasis in Zambia.

This paper attempts to approach an accurate report of prevalence of schistosomiasis in Zambia by bringing together several reports. A review of some early prevalence studies in Zambia shows the prevalence of S. hematobium infection to be (14-40%) and that for S. mansoni to range from (0-7%), in the Northern and Luapula Provinces. The areas around Lakes Kariba in the south, and Bangweulu in the north had prevalence rates of (3-35%) for S. hematobium and (2-6%) for S. mansoni. A nationwide survey found the overall prevalence of S. hematobium to be about 16%. The Gwembe Valley in the South had the highest prevalence of 57.9% for S. hematobium; S. mansoni with a prevalence of (45-77%) in the Northern Province from more recent studies is not very widespread. A comprehensive study performed between 1969-73 covered almost the entire rural population and found an overall prevalence of 16.8%, varying greatly between ecozones. The 5-14 year age group showed the highest prevalence. A 1976-82 study of rural primary school children in several provinces found high prevalence rates. Specimen gathering and analysis is described for most studies analyzed, revealing some inconsistencies threatening the reliability of data. Available data do show the spotty and local nature of the prevalence rates between areas. There have not been many studies of S. mansoni prevalence, possibly due to the difficulties involved with the collection of stool specimens, but prevalence (especially seasonal) has been shown to be high in certain areas (although low generally). The areas around the 2 major lakes show considerable prevalence of both parasites, and further study is needed on the health impact of man-made lakes in Zambia and elsewhere.