Impact of some environmental factors on distribution of certain vector snails in five Egyptian Governorates

The present study showed that the distribution of the intermediate host snails of Fasciola sp. and Schistosoma sp. varied among the five surveyed Egyptian governorates. It was found that the ratios of distribution of Lymnaea natalensis, Bulinus truncatus and Biomphalaria alexandrina snails of the total surveyed sites were 44.1%, 26.9% and 4.9% respectively. Moreover, infected L. natalensis, B. truncatus and B. alexandrina snails in these sites were 1.96%, 3.4% and 0.98% respectively. However, infected L. natalensis and B. truncatus were found in Damietta and Beheira, while infected B. alexandrina were found only in Giza. Spring was the highest season in percentage of collected snails (38.9%), while summer was the lowest one (8.8%). L. natalensis, B. truncatus and B. alexandrina showed high distribution in Ismailia, Damietta and Giza governorates as represented by 4.16, 4.38 and 0.51 snails/site respectively. Some environmental factors were found affecting the distribution of snails. The means of pH and temperature in positive sites for vector snails were 6.8 and 26.7°C respectively. L. natalensis, B. truncatus appeared in water of electric conductivity mean of 415.5 μ.mhos/cm and 284.5 ppm of mean total dissolved salts, while B. alexandrina was found at 481 μ.mhos/cm and 603 ppm respectively.