Population Abundance and Disease Transmission Potential of Snail intermediate hosts of Human Schistosomiasis in Fishing Communities of Mwanza Region, North-western, Tanzania

Schistosomiasis remains a major public health problem with estimated 240 million cases worldwide whereby more than 90% of these occur in Sub-Saharan Africa. Tanzania is ranked second after Nigeria in terms of disease burden with prevalence of infection as higher as 100% in some communities. We conducted a cross-sectional malacological survey to examine for abundance, identity and disease transmission potential of snails in fishing communities of Mwanza region, Tanzania. Snails were collected from selected sites with high human water contact using standard methods. The most abundant snails species were Biomphalaria sudanica which accounted for 81.25% (n=1470) of snails collected.. Bulinus nasutus was the second abundant snail accounting for 13.87% (n=251) while Bulinus globosus was the least abundant snail accounting for 4.86% (n=88). Only 0.57% (n=11) of collected Biomphalaria snails were shedding S. mansoni cercariae while none of the Bulinus snail species were shedding cercariae. Vegetation cover was significantly associated with snail abundance (P<0.001). A positive correlation between water temperature and snail abundance was observed. No correlation was found between pH and snail abundance. The low numbers of snails shedding schistosome cercariae could be as a result of many factors including timing of the study in relation to transmission season. Keyword: Schistosomiasis, Biomphalaria, Bulinus, Cercariae, Mwanza region.