Tissue responses exhibited by Biomphalaria alexandrina snails from different Egyptian localities following Schistosoma mansoni exposure

► Populations of snails of the same species show different degrees of susceptibility to infection. ► The dynamic interaction between molluscs and their trematode parasites leads either to a state of co-existence or to incompatibility. ► Biomphalaria susceptibility to Schistosoma mansoni infection varies among snails according to geographic areas in which both snails and the trematode occur. ► Snail's hemocytes responses towards S. mansoni are related to the susceptibility of these snails.