Fascioliasis due to Fasciola hepatica and Fasciola gigantica Infection: an update to this ‘Neglected’ Neglected Tropical Disease
Sherry Bakhtiari
San jacinto College

Fascioliasis due to Fasciola hepatica and Fasciola gigantica Infection: an update to this ‘Neglected’ Neglected Tropical Disease Fascioliasis is a trematode flatworm infection caused by the sheep and cattle liver fluke Fasciola hepatica or Fasciola gigantica. Infective Fasciola larvae are found in contaminated water, either stuck to water plants or floating in the water, often in marshy areas, ponds, or flooded pastures. People and animals typically become infected by eating raw watercress or other water plants. Fasciola parasites develop into adult flukes in the bile ducts of infected mammals, which pass immature Fasciola eggs in their feces. The next part of the life cycle occurs in freshwater. After several weeks, the eggs hatch, producing a parasite form known as the miracidium, which then infects a snail host. Under optimal conditions, the development process in the snail may be completed in 5 to 7 weeks; cercariae are then shed in the water around the snail. The cercariae lose their tails when they encyst as metacercariae (infective larvae) on water plants. In contrast to cercariae, metacercariae have a hard outer cyst wall and can survive for prolonged periods in wet environments. Fasciola hepatica is found in more than 50 countries, in all continents except Antarctica. It is found in parts of Latin America, the Caribbean, Europe, the Middle East, Africa, Asia, and Oceania. Fasciola gigantica is less widespread. Human cases have been reported in the tropics, in parts of Africa and Asia, and also in Hawaii.
In acute infection, immature flukes migrate through the intestinal wall, the peritoneal cavity, the liver capsule, and the parenchyma of the liver before entering the biliary ducts.
Acute infection causes abdominal pain, hepatomegaly, nausea, vomiting, intermittent fever, urticaria, eosinophilia, malaise, and weight loss due to liver damage. Chronic infection may be asymptomatic or lead to irregular abdominal pain, cholelithiasis, cholangitis, obstructive

jaundice, or pancreatitis. Heavy infection can cause sclerosing cholangitis and biliary cirrhosis. Ectopic lesions may occur in the intestinal wall, lungs, or other organs. Pharyngeal fascioliasis has been reported after consumption of infected raw liver in the Middle East. CT frequently shows hypo dense lesions in the liver during the acute stage of infection. In chronic infections, eggs may be recovered from the stool or from duodenal or biliary materials. The eggs are indistinguishable from those of Fasciolopsis buski.
Treatment is with triclabendazole (10 mg/kg once after meals or, for severe infections, twice 12 hour apart), Alternatives include nitazoxanide 500 mg for 7 days and bithionol 30 to 50 mg/kg every other day for 10 to 15 doses. Treatment failures are common with praziquantel.

References:

Tolan, R. (2011). Fascioliasis due to Fasciola hepatica and Fasciola gigantica Infection: An update to this ‘Neglected’ Neglected Tropical Disease. Lab Medicine, 42(2), 65-128.

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