Effect of Infection with Shistosoma mansoni on Some Biological Parameters in Biomphalaria alexandrina Snails

Histological alterations in digestive gland as well as hematological and biochemical changes in haemolymph of Shistosoma mansoni infected Biomphalaria alexandrina snails were studied. The results showed great histological damages in tissues of the digestive gland of infected snails with large numbers of sporocysts and cercariae at several stages of development encircled by cycts in tissue of digestive gland. A detailed light (LM) and scanning electron microscopy(SEM) of the haemocytes in infected snails were described to evaluate the capability to respond to parasitic infections. Three main haemocytes categories could be distinguished namely: hyalinocytes, agranulocytes and granulocytes according to the presence or absence of granules. Phagocytic ability and pseudopodial formation were obviouisly increased in infected snails. The results showed a significant decrease in total protein and albumin content with elevation of total lipids content and glucose concentration in the haemolymph of infected snails. It was concluded that haemocytes (SEM) in infected snails have large cells with a large imagination, smooth surface and secretion particles adherent to these cells to respond to parasitic infections.