PARAMPHISTOMUM-DAUBNEYI AND FASCIOLA-HEPATICA - THE EFFECT OF DUAL INFECTION ON PREVALENCE AND CERCARIAL SHEDDING IN PREADULT LYMNAEA-GLABRA

Preadult Lymnaea glabra measuring 4-6 mm in height were each exposed t o 1 Paramphistomum daubneyi miracidium before being exposed to 1 mirac idium of Fasciola hepatica. Total prevalence of infection in the snail groups from 3 different populations ranged from 33% to 39%. In each g roup, snails harboring larval forms of P. daubneyi, F. hepatica, or bo th, were noted. If the results from the 3 snail populations are pooled , the total prevalence of snail infection was 13.6% in snails harborin g only F. hepatica larvae, 13% in those harboring only P. daubneyi lar vae, and 10% in those with both trematodes. Cercarial shedding was obt ained from snails harboring F. hepatica larval forms; in the case of s nails infected with both trematodes, the mean number of metacercariae ranged from 13 to 21 for F. hepatica, and from 8 to 14 for P. daubneyi . No infected snails were found in snail groups exposed only to 1 trem atode miracidia.