Final report : role of biotic and abiotic factors in controlling disease - transmitting snails in Kenya -- an experimental study

The purpose of this study was to develop a biological method to control snail vectors. The study revealed that the North American red swamp crayfish Procambarus clarkii is a voracious predator of disease-transmitting pulmonate snails and can reduce or eliminate target snail populations in natural habitats in Kenya. P. clarkii, originally introduced into East Africa for aquaculture purposes, is now widely distributed in Kenya, and supports a small but thriving export industry centered at Lake Naivasha. The judicious use of crayfish in schistosomiasis control can provide a new weapon with which to control snails and break the cycle of disease transmission. However, because crayfish also attack non-target species, their use should be restricted to those human-made earthen dams -- which are ubiquitous in Kenya -- which function as transmission sites and do not harbor endangered biota. The study discusses the above issues in depth, as well as studies of other control agents such as competitor/predator snails, the development of a geographic information system to facilitate analysis of factors influencing snail distribution, and spin-off studies pertaining to snail systematics. (Author abstract)