Fasciolosis

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Fasciolosis is an important helminth disease caused by two trematodes Fasciola hepatica (the common liver fluke) and Fasciola gigantica. This disease belongs to the plant-borne trematode zoonoses. In Europe, the Americas and Oceania only F. hepatica is a concern, but the distributions of both species overlap in many areas of Africa and Asia.^[1]

The definitive host range is very broad and includes many herbivorous mammals, including humans. The life cycle includes freshwater snails as an intermediate host of the parasite.^[2] Recently, worldwide losses in animal productivity due to fasciolosis were conservatively estimated at over US$3.2 billion per annum.^[3] In addition, fasciolosis is now recognized as an emerging human disease: the World Health Organization (WHO) has estimated that 2.4 million people are infected with Fasciola, and a further 180 million are at risk of infection.^[4]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

The development of infection in definitive host is divided into two phases: the parenchymal (migratory) phase and the biliary phase.^[1] The parenchymal phase begins when excysted juvenile flukes penetrate the intestinal wall. After the penetration of the intestine, flukes migrate within the abdominal cavity and penetrate the liver or other organs. F. hepatica has a strong predilection for the tissues of the liver.^[2] Occasionally, ectopic locations of flukes such as the lungs, diaphragm, intestinal wall, kidneys, and subcutaneous tissue can occur.^[3][4] During the migration of flukes, tissues are mechanically destroyed and inflammation appears around migratory tracks of flukes. The second phase (the biliary phase) begins when parasites enter the biliary ducts of the liver. In biliary ducts, flukes mature, feed on blood, and produce eggs. Hypertrophy of biliar ducts associated with obstruction of the lumen occurs as a result of tissue damage.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

• Fasciola hepatica
• Fasciola gigantica

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Human and animal fasciolosis occurs worldwide.^[1] While animal fasciolosis is distributed in countries with high cattle and sheep production, human fasciolosis occurs, excepting Western Europe, in developing countries. Fasciolosis occurs only in areas where suitable conditions for intermediate hosts exist.

Studies carried out in recent years have shown human fasciolosis to be an important public health problem.^[2] Human fasciolosis has been reported from countries in Europe, America, Asia, Africa and Oceania. The incidence of human cases has been increasing in 51 countries of the five continents.^[3][4] A global analysis shows that the expected correlation between animal and human fasciolosis only appears at a basic level. High prevalences in humans are not necessarily found in areas where fasciolosis is a great veterinary problem. For instance, in South America, hyperendemics and mesoendemics are found in Bolivia and Peru where the veterinary problem is less important, while in countries such as Uruguay, Argentina, and Chile, human fasciolosis is only sporadic or hypoendemic.^[4]

In Europe, human fasciolosis occur mainly in France, Spain, Portugal, and the former USSR.^[4] France is considered an important human endemic area. A total of 5863 cases of human fasciolosis were recorded from nine French hospitals from 1970 to 1982.^[5] Concerning the former Soviet Union, almost all reported cases were from the Tajik Republic.^[4] Several papers referred to human fasciolosis in Turkey.^[6] Recently, serological survey of human fasciolosis was performed in some parts of Turkey. The prevalence of the disease was serologically found to be 3.01% in Antalya Province, and between 0.9 and 6.1% in Isparta Province, Mediterranean region of Turkey.^[7] In other European countries, fasciolosis is sporadic and the occurrence of the disease is usually combined with travelling to endemic areas.

In North America, the disease is very sporadic. In Mexico, 53 cases have been reported. In Central America, fasciolosis is a human health problem in the Caribbean Islands, especially in zones of Puerto Rico and Cuba. Pinar del Rio Province and Villa Clara Province are Cuban regions where fasciolosis was hyperendemic. In South America, human fasciolosis is a serious problem in Bolivia, Peru, and Ecuador. These Andean countries are considered to be the area with the highest prevalence of human fasciolosis in the world. Well-known human hyperendemic areas are localized predominately in the high plain called Altiplano. In the Northern Bolivian Altiplano, prevalences detected in some communities were up to 72% and 100% in coprological and serological surveys, respectively.^[3] In Peru, F. hepatica in humans occurs throughout the country. The highest prevalences were reported in Arequipa, Mantaro Valley, Cajamarca Valley, and Puno Region.^[8] In other South American countries like Argentina, Uruguay, Brazil, Venezuela and Colombia, human fasciolosis appear to be sporadic, despite the high prevalences of fasciolosis in cattle.

In Africa, human cases of fasciolosis, except in northern parts, have not been frequently reported. The highest prevalence was recorded in Egypt where the disease is distributed in communities living in the Nile Delta.^[8]

In Asia, the most human cases were reported in Iran, especially in Gīlān Province, on the Caspian Sea. It was mentioned that more than 10,000 human cases were detected in Iran. In eastern Asia, human fasciolosis appears to be sporadic. Few cases were documented in Japan, Koreas, Vietnam, and Thailand.^[3]

In Australia, human fasciolosis is very rare (only 12 cases documented). In New Zealand, F. hepatica has never been detected in humans.^[3]

Countries where fasciolosis in livestock was repeatedly reported:

• Europe: UK, Ireland, France, Portugal, Spain, Switzerland, Italy, Netherlands, Turkey, Germany, Poland
• Asia: Russia, Thailand, Iraq, Iran, China, Vietnam, India, Nepal, Japan, Korea, Philippines
• Africa: Kenya, Zimbabwe, Nigeria, Egypt, Gambia, Morocco
• Australia and the Oceania: Australia, New Zealand
• Americas:United States, Mexico, Cuba, Peru, Chile, Uruguay, Argentina, Jamaica, Brazil

On Sepember 8, 2007, Veterinary officials in South Cotabato, Philippines said that laboratory tests on samples from cows, carabaos, and horses in the province‘s 10 towns and lone city showed the level of infection at 89.5%, a sudden increase of positive cases among large livestock due to the erratic weather condition in the area. They mus be treated forthwih to prevent complications with Surra and Hemorrhagic Septicemia diseases. Surra already affected all barangays of the Surallah town.^[9]

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