The role of Chaetogaster limnaei in the dynamics of trematode transmission in natural populations of freshwater snails.

Chaetogaster limnaei, an oligochaete was always found infesting Bulinus (Phy.) globosus, B.(B.) forskalii and Lymnaea natalensis in Bo, Sierra Leone, living below the shell or embedded in the mucus of the foot. The worms had no preference for snails with trematode infection. The population was highest in the dry season when fewer snails were infected by trematodes. This is suggested to be a result of the protection the worms give to snails against invading miracidia.