Effects of Schistosoma mansoni on the nutrition of its intermediate host, Biomphalaria glabrata.

Biomphalaria glabrata infected with Schistosoma mansoni and maintained on an artificial diet of Spirulina alga displayed reduced growth during the 5 wk following patency. Food consumption per unit snail weight was unaffected. Infected snails also failed to lay eggs. No difference in percentage of assimilation was observed between control and infected individuals, but infected snails had significantly decreased gross conversion efficiencies. The effects of infection on nutrition of B. glabrata were similar to those observed in nutrient-deprived snails fed diets containing low Spirulina levels. Nutrient deprivation, however, did not alter conversion efficiency.