ECOLOGICAL-STUDIES OF BULINUS-ROHLFSI, INTERMEDIATE HOST OF SCHISTOSOMA-HAEMATOBIUM IN VOLTA LAKE

  • 1 January 1977
    • journal article
    • research article
    • Vol. 55  (6) , 715-730
Abstract
In an ecological study of cercarial transmission of S. haematobium in the Volta Lake, Ghana, habitat observations and sampling of B. truncatus rohlfsi were conducted within a 60 km stretch of shoreline. Human water contact sites in each village undergo constant changes in shape and vegetation. Snail sampling surveys in water contact sites were carried out monthly (for 27 mo.) in 8 villages using newly designed palm-leaf traps, and in 8 additional villages (for 16 mo.) using a modification of Olivier and Sneidermann''s man-time method. Results to date confirm the finding by Chu and Vanderburg that cercarial transmission in the lake takes place almost exclusively within water contact sites. Additional results indicate that even within individual water contact sites this transmission is focal, most infected snails being found very close to the shoreline. Transmission also varies significantly according to shape, vegetation and geographical location of the water contact sites, and is distinctly seasonal in most villages. Control of cercarial transmission in the Volta Lake is attainable and feasible with existing methods.