HISTOLOGICAL STUDIES ON THE CONSEQUENCE ANTAGONISM OF ECHINOSTOMA LIEI TO SCHISTOSOMA MANSONI IN BIOMPHALARIA ALEXANDRINA SNAILS

Egypt. J. Exp. Biol. (Zoo.). 2007; 3(0): 145-150

H o d a A b d e l H a m i d, A m i n a E l - H u s s e n y, A hme d T a n t a w y, S h a d i a M . E l - D a f r a w y.

Abstract
The antagonism of Echinostoma liei to Schistosoma mansoni in Biomphalaria alexandrina snails hermaphrodite glands was studied. Biomphalaria alexandrina were exposed to Schistosoma mansoni and Echinostoma liei as single and double infection; simultaneously, S. mansoni then E. liei (after 1 or 3 days) and E. liei then S. mansoni (after 1 or 3 days). The schistosome infection was reduced by 71.1% in snails exposed to the two parasites simultaneously. Snails exposed to E. liei firstly, one or three days, showed the highest schistosome reduction rate (100% and 94.1%, respectively). The histological sections in the hermaphrodite glands of double infected snails after shedding cercariae showed that E. liei was markedly dominant in all experiments especially when snails exposed to E. liei atfirst. The echinostome mature rediae prevented the schistosome sporocysts to develop by surrounding and attacking them leading to destroying or strongly reducing the schistosome infection. Key words: Biomphalaria alexandrina, Echinostoma liei, Schistosoma mansoni