The influence of second intermediate host species on the infectivity of metacercarial cysts of Echinoparyphium recurvatum

The potential influence of second intermediate host species on the infectiv ity of metacercarial cysts of Echinoparyphium recurvatum to the definitive host Anas platyrhynchos was examined experimentally. Echinoparyphium recurv atum metacercarial cysts were obtained from the following experimentally in fected second intermediate hosts 14 days post expsoure to cercariae: Lymnae a peregra; Physa fontinalis; L, stagnalis; Planorbis planorbis; Biomphalari a glabrata; tadpoles of the amphibian Rana temporaria. Metacercarial cysts from each of these hosts were fed, in doses of 50 cysts per individual, to separate groups composed of between four and eight, S-day-old A. platyrhync hos ducklings. All A, platyrhynchos were necropsied 15 days post-infection and the number, size, and reproductive status of E. recurvatum worms in the intestine was recorded. Analyses of variance on the number (transformed lo g (x + 1)) and size of worms revealed no significant differences in worms o riginating from metacercariae formed in the different second intermediate h osts (worm number P > 0.05, and worm size P > 0.05). All worms recovered we re found to be gravid. It is therefore concluded that the species of second intermediate host utilized does not influence the infectivity of the metac ercarial cyst of E, recurvatum, nor the subsequent establishment and reprod uctive status of the parasite in A. platyrhynchos.