Dynamics of elimination of the eggs of Fasciola hepatica (Trematoda, Digenea) in the faeces of cattle in the Porma Basin, Spain.

In order to contribute to the knowledge of the epizootiological conditions in which fasciolosis develops in the León mountains, the elimination of Fasciola hepatica eggs in 10% of the total number of cattle (1301 samples) at five locations in the Porma river basin was recorded at monthly intervals between March 1986 and March 1987. The parasite was found in cattle [29.5% prevalence, average of 51.6 +/- 4.5 eggs g-1 (e.p.g.) faeces] throughout the year. The main egg elimination period was winter-spring, with maximum prevalence in January and maximum e.p.g. in February-March. Prevalence of infection in cattle generally increased with the host's age, whilst the average e.p.g. varied between different age groups.