Endemicity and seasonality of transmission of human schistosomiasis in Ile-Ife, south western Nigeria.

Endemicity and seasonality of transmission of Schistosoma mansoni and S. haematobium were studied in Ile-Ife, south western Nigeria. Transmission of S. mansoni was demonstrated throughout the year in a man-made dam, whereas transmission of S. haematobium in a stream only occurred in the dry season. This difference in the transmission patterns should be considered when incorporating community-based focal plant molluscicide application in the integrated strategy for the control of schistosomiasis morbidity.

Molluscicidal trials and correlation between the presence of Tetrapleura tetraptera in an area and the absence of the intermediate hosts of schistosomiasis and fascioliasis in southwest Nigeria.

A schistosomiasis research project, carried out in Southwest Nigeria, yielded data by which it was possible to relate snail recovery from potential transmission sites to the presence or absence of Tetrapleura tetraptera. A significant negative correlation with snail numbers was found for distance of T. tetraptera from transmission sites and fruiting of the trees when these variables were tested individually. There were no significant differences between individual variables such as pH, Ca2+ concentrations and temperatures for these snail habitats but these variables produced significant positive correlation with the number of snails recovered. Thus, the presence of T. tetraptera appeared to be the most important limiting factor for the presence of snails. Aqueous extracts of T. tetraptera were effective as a molluscicide against Bulinus globosus and Lymnaea natalensis. However, pollution of the environment by oils reduced or abolished the molluscicidal activity of T. tetraptera. The results indicate that the planting of T. tetraptera has potential for the local control of schistosomiasis.