Fascioliasis

Abstract

Human fascioliasis is an important public health problem in many regions and livestock infection is a veterinary problem worldwide. This disease is caused by the liver fluke species Fasciola hepatica of worldwide distribution and F. gigantica restricted to regions of Africa and Asia. Their two-host life cycle is similar, including specific freshwater lymnaeid snails as vectors. The major human health problems are known in Andean countries, the Caribbean, Northern Africa, Near East, Southeast Asia and Western Europe. In human hyperendemic areas, children and females are the most affected. Human fascioliasis shows a marked heterogeneity of epidemiological situations and transmission patterns. Variation of climatic factors and anthropogenic environmental modifications give rise to different fascioliasis seasonality and long-term disease risk trends. There are many human infection sources, local diet and cultural traditions being important. The rapid and potent ability of fasciolids to suppress the immune response explains why hosts do not develop resistance and the frequency of pathogen coinfections. The disease is chiefly confined to the liver, including hepatic lesions, fibrosis and chronic inflammation. Juvenile flukes may cause ectopic fascioliasis. Clinical manifestations are evident in both invasive and biliary periods. Diagnosis is mainly made by coprological and serological techniques. Among the useful drugs, triclabendazole is of choice at present. Prognosis depends on treatment promptness. Serious complications, sequelae and death causes should be highlighted. New knowledge has allowed improvement of individual infection prevention measures and community control. Challenges appear in vaccinology, indicating that a human vaccine is still far from affordable.