Fascioliasis in cattle. An epidemiological field trial in Denmark
Nielsen, K.; Nansen, P.; Rasmussen, P.; Lund, H.; Riising, H.J.
Nordisk Veterinaermedicin 25(6): 281-290
1973
ISSN/ISBN: 0029-1579 PMID: 4768221 Document Number: 67800
An epizootiological field trial was carried out over 3 grazing seasons (1970-72) in a Fasciola hepatica enzootic area of Jutland, Denmark, to determine the significance of an overwintering infection under Danish conditions. The level of metacercarial infection on the pasture was ascertained by counting the numbers of flukes established in the bile ducts of fluke-free tracer calves turned out to graze on the area over a certain period. Owing to a very severe winter in 1969-70 and a very dry June 1970, there was no overwintering infection in the first season and very little so-called summer infection. During the 1971 and 1972 grazing seasons there were significant overwintering infections. However, the infection resulting from metacercariae developing from the so-called summer infection in the snail vector yielded the most significant contribution to the total fluke population. The results are discussed in relation to the planning of control measures.