Résumé
Lymnaea cailliaudia were reared in stock culture and subjected to either 7-day or 60-day acclimatization periods in a complex CaCo[3] media with calcium values ranging from 1.5mg/L to 75mg/L, Following 30-day acclimatization Snail from group I were each exposed to 100-eggs of Clinostomum tilapiae. Snails of group II were each exposed to a 10-eggs. Snails of both experimental regimes were observed for mortality, growth, rate of infection and number of cercariae shed. Group I snails were also monitored for fecundity during acclimatization and following eggs exposure. Calcium levels 1.5 and 75mg/L resulted in snail mortality. Shell growth and rates of infection were positively correlated with calcium maintenance level. Snails with high fecundity prior to eggs exposure subsequently shed more cercariae. In contrast, post exposure fecundity of snails reared in media with up to 30 mg/L calcium were negatively correlated with calcium level, rate of infection and number of cercariae shed. Maximal cercarial shedding occurred at 30mg/L calcium. These results suggest that environmental calcium affect both the distribution patterns of snail hosts of Clinostomum tilapiae and the productivity of intramolluscan infection