Urinary and intestinal schistosomiasis in the Tono Irrigation Scheme, Kassena/Nankana District, upper east region, Ghana.

Abstract

Human- and snail-related aspects of transmission of urinary and intestinal schistosomiasis were studied in the Tono Irrigation Scheme in northern Ghana. The scheme became operational in 1977. In some schools, prevalences and intensities of both Schistosoma mansoni and S. haematobium infection were alarmingly high, pointing to human schistosomiasis being at least focally a health problem of major public health concern. Positive correlations between intensity of schistosome infection, as measured by egg output, with frequency of visible haematuria and history of haematuria point to opportunities for community-based assessment of morbidity and identification of high risk population subgroups. Bulinus globosus is the most important snail host for S. haematobium while Biomphalaria pfeifferi serves as host for S. mansoni. While transmission of S. mansoni is taking place only in the main canal, transmission of S. haematobium takes place in all parts of the irrigation system (lateral canal, night storage dam, main reservoir). Transmission of both S. mansoni and S. haematobium is rather focal and a seasonal pattern of transmission is indicated with peak transmission taking place during the beginning of the dry season. The high endemicity and the transmission patterns described in this study call for an integrated approach to schistosomiasis morbidity control in the area.