Liver fluke-induced infection is a major public health problem in Europe and South-East Asia, especially Thailand. It is a food borne infection that occurs in regions where uncooked cyprinoid fish is a staple of the diet. Due to poor sanitation, the feces of infected people is deposited in water resources, which in turn infect the fish, through snails that serve as intermediate hosts. This sets off a vicious unending cycle of infection, that results in Liver Cancer.
Approximately 10-25% of liver cancers are said to be a resultant of liver fluke infection. In the year 2004, 28000 people in Thailand succumbed to liver fluke-associated cholangiocarcinoma (CCA).
Hepatocellular Carcinoma (HCC), the other common form of liver cancer is more common worldwide but comparatively less common in Thailand. CCA is a major cause for alarm and the prognosis is poor. It has been observed that patients affected with severe CCA survive for typically 65 days post infection.
Opisthorchis viverrini, is the parasite that causes the highest number of CCA infections. While some heavily infected patients exhibit abdominal pain, a large number of patients go unnoticed owing to the lack of conclusive symptoms. Enlargement of the gall bladder is observed in infected patients, but this can be reversed by the elimination of parasites. Jaundice is the main clinical manifestation that results in the hospitalization of 60% of patients suffering from CCA.
Pathological consequences of O. viverrini infection occur mainly in the liver, extra-hepatic bile ducts and gallbladder. Cholangiocarcinomas tend to grow slowly and to infiltrate the walls of the ducts, dissecting along tissue planes. Local extension occurs into the liver and regional lymph nodes. Life-threatening infection (cholangitis) may occur that requires immediate antibiotic intervention and aggressive biliary drainage.
Cholangiocarcinoma is a major cause of concern that has plagues the world, and Thailand, in particular for the last few decades. The only process of stopping the vicious cycle of infection involves mass treatment of infected individuals with anthelmintic therapy that causes the expulsion of these parasites. While this would serve as only a stop gap measure, sanitation and hygiene needs to be improved to curb cholangiocarcinoma in the long run.
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