Flukes: Old Parasites but New Emergence

Flukes of ruminants are flatworm (trematodes) parasites living in the liver, fore stomachs or blood vessels, of which 40 different species may be present. Many other trematodes are parasites of fishes, poultry, carnivores and man. The liver fluke, Fasciola hepatica, was first described in France by Jean de Brie (1379), in his treatise on wool production and sheep management for the king Charles V. He made mention of the disease “liver rot” in sheep but did not actually describe the appearance of the worm in this book. He did not associate the liver fluke with the disease but thought that this was a consequence of the liver being affected by toxic substances produced by certain plants eaten by the sheep (Dalton, 1998). Since these times, flukes of cattle have been extensively studied: Fasciola hepatica and Dicrocœlium lanceolatum in the liver, Paramphistomum daubneyi in the fore stomach are widespread in countries with temperate climates. In this paper, tropical species will not be covered, examples of these include F. gigantica and Paramphistomum explanatum of the liver, Eurytrema pancreaticum of the pancreas, Cotylophoron sp, Carmyerius sp etc from the upper alimentary tract, Homalogaster sp of the large intestine. Schistosoma bovis and S. nasale etc are living in blood vessels. Worldwide, 700 millions of cattle are exposed to liver flukes, annually and the annual cost is 3,2 10 US$ (WAAVP 2005).