Effect of certain salts on biomphalaria Alexandria snail and their susceptibility to schistosoma mansoni infection

ABSTRACT

The effect of magnesium sulphate, calcium sulphate, manganese sulphate, sodium chloride and potassium chloride, on survival of B.alexandrina snails and their susceptibility to S.mansoni infection was evaluated. It was found that no snail was infected among survived ones in groups maintained continuously for 14 weeks post miracidial exposure at the experimental salts. However, snails in groups that were maintained at the experimental salts for 24 hours [during miracidial exposure] and kept after that in clean water were susceptible to infection at varying degrees. Although miracidia exposed to the experimental salts were alive after 2 hours, complete death was recorded after 24 hours of exposure to 200 ppm MnSO[4] [Mn = 65 ppm] and 1000 ppm from the other experimental salts The present work showed that MnSO[4] was more toxic to B. alexandrina snails than MgSO[4] and CaSO[4] either pre-or post exposure to S.mansoni miracidia. The suppressive effect of high calcium ions on cercarial production was supported by absence of infection among snails subjected to 2500 ppm CaSO[4] [Ca=581.3 ppm]. Moreover, increasing NaCl concentration from 1000 ppm to 2000 ppm [Na = 393.2, and 786.4 ppm] during snails exposure to miracidia caused more reduction in their cercarial output