The metacercariae remain on the surface of aquatic plants and grasses until they are ingested by the final host. When ingested, the metacercariae bores their way [excyst] through the wall of the small intestine and eventually find their way into the body cavity, where they seek out the liver. Here, the juvenile fluke will bore through the liver’s capsule and reach the bile ducts by passing through the parenchyma of the liver (Anonymous, 6). It is here where the worm will live for many years, obtaining unlimited amounts of nutrients by maintaining permanent contact with the bile stream.
It will then continue to perpetuate, shedding approximately 4 eggs per second [about 20,000 eggs per day] (Espino & Dumenigo, 540). The eggs, which are relatively large (about 140 microns) and are provided with an operculum, will then reach the intestine via the bile where it is eventually evacuated through the feces to continue the cycle (Anonymous, 6). Majority of people that are infected have low worm burdens and usually do not manifest significant chronic symptoms.
The infection has two different stages, in which signs and symptoms differ. During the period of migration or hepatic phase of the illness, the acute clinical syndrome is characterized by prolonged fever, pain in the right hypochondrium, hepatomegaly, pruritis and urticaria; hypergammaglobulinemia and marked eosinophilia are the classical signs and symptoms usually seen during this stage. Additionally, mild hepatitis, severe subcapsular hemorrhage and frank hepatic necrosis may also be detected.
However, asymptomatic acute infection has been reported in England and seems to be common in Peru. After the flukes enter the bile ducts [biliary stage], the symptoms appear to decline and may disappear completely. The biliary stage usually presents with intermittent right upper quadrant pain with or without cholangitis or cholestasis. During this stage, the flukes browse on the mucosa blood and tissue fluids of the biliary tract, and their presence may be related to the development of local fibrosis.
Animals with particularly heavy worm burdens may also develop chronic biliary tract disease; however, the condition is rarely reported in infected humans (Anonymous, 7; Yagzan Aksoy et al. , 41). Diagnosis is mainly via stool studies, serology, radiographic techniques or biopsy while treatment usually involves Triclabendazole and bithionol which are found to be effective agents for treatment of fascioliasis (Yagzan Aksoy et al. , 41).
Works Cited Anonymous. “Helminths in the Class Trematodes Infecting Man. ” Www. Sums. ac.ir. Accessed 23 April 2009 <http://www. sums. ac. ir/~parasito/1. pdf> Espino, Ana M. , Bianca E. Dumenigo. “Fasciola hepatica. ” International Handbook of Foodborne Pathogens. Edited by Marianne D. Miliotis and Jeffrey W. Bier. CRC Press, 2003. 539-562. Yagzan Akso, Duygu, Ulku Kerimoglu, Aytekin Oto, Sibel Erguven, Serap Arslan, Serhat Unal, Figen Batman & Yusuf Bayraktar. “Fasciola hepatica Infection: Clinical and Computerized Tomographic Findings of Ten Patients. ” Turkish Journal of Gastroenterology 17(1): 40-45, 2006.