Fascioliasis

Infection with the liver fluke Fasciola hepatica occurs throughout the world wherever sheep are raised. The adult worms live in the biliary system of sheep, cattle and man , where they deposit their eggs. The eggs pass into the intestines and are eliminated in the faeces. They complete their development into miracidia in freshwater and infect the intermediate snail host. Multiplication occurs within the snail and cercariae emerge and undergo encystment into metacercariae attached to aquatic plants. When these are ingested they excyst and the larvae penetrate through the intestinal wall and peritoneum, passing through the capsule of the liver and eventually reaching the biliary tract. The clinical illness is characterized by fever, eosinophilia and painful enlargement of the liver. Occasional cases have resulted in biliary obstruction or cirrhosis. Diagnosis is made by finding the eggs in faeces or bile. There is no proven effective treatment for the infection.