Standardisation of egg-viability assays for Fasciola hepatica and Calicophoron daubneyi: A tool for evaluating new technologies of parasite control.

Fasciola hepatica and Calicophoron daubneyi, liver and rumen flukes respectively, infect ruminants throughout Europe. There is considerable interest in the development of vaccines and in testing new potential anthelmintic agents against these species. One potential target of new control measures is the parasite egg, as interference at this stage of the life cycle could aid in blocking the transmission of infection, and some experimental vaccines have been shown to affect egg viability. In this study, we describe the standardisation of protocols to evaluate the viability of eggs of these two parasites. Eggs were recovered from adult parasites collected in a commercial abattoir, from naturally infected cattle. A protocol for in vitro development of F. hepatica eggs was optimised based on previously published methods, with variations in duration and temperature of incubation. A new protocol for measurement of rumen fluke egg development in vitro was designed, based on testing different temperatures and periods of incubation, with or without light exposure. The protocols described here may be used in the future for comparing experimental groups when new technologies for parasite control are tested. In addition, the methods described for C. daubneyi present new information on the biology of this parasite.