Natural infection of land-snails by protostrongylids on a pasture grazed by sheep in the Rabat area of Morocco.

The output by sheep of first-stage protostrongylid larvae, and the population density and level of infection of terrestrial molluscs were assessed monthly during a 1-year study. Limax maximus was the most infected mollusc. Juveniles were less infected than adults, for Cernuella virgata and Theba pisana; the reverse was observed for Otala lactea. Banded individuals had a lower intensity of infection than the non-banded ones for C. virgata and T. pisana. Sixty-one percent of protostrongylid larvae in molluscs on the pastures studied were found in C. virgata, and 25% in O. lactea. The infectivity of the pasture for sheep was related to rainfall.