Opisthorchiasis: An Emerging Foodborne Helminthic Zoonosis of Public Health Significance

Opisthorchiasis is an emerging foodborne parasitic zoonosis that has been reported from developing as well as developed nations of the world. Globally, around 80 million people are at risk of acquiring Opisthorchis infection. The source of infection is exogenous, and ingestion is considered as the primary mode of transmission. Humans get the infection by consuming raw or undercooked fish. In most cases, the infection remains asymptomatic. However, in affected individuals, the clinical manifestations are manifold. Occasionally, complications including cholangitis, cholecystitis, and cholangiocarcinoma are observed. The people who have the dietary habit of eating raw fish usually get the infection. Certain occupational groups, such as fishermen, agricultural workers, river fleet employees, and forest industry personnel are mainly infected with Opisthorchis. The travelers to the endemic regions who consume raw fish are exposed to the infection. Parasitological, immunological, and molecular techniques are employed to confirm the diagnosis of disease. Treatment regimens include oral administration of praziquantel and albendazole. In the absence of therapy, the acute phase transforms into a chronic one that may persist for two decades. Presently, there is no vaccine available against Opisthorchis species. Elimination of human host reservoir can be achieved by the examination of stool and treatment of the positive cases. Consumption of thoroughly cooked fish, protection of water bodies, decontamination of sewage, dehelminthization of domestic carnivores, proper washing of hands and kitchen utensils after processing raw fish, and education of the people about the hazards of eating raw or undercooked fish are the practical strategies for the prevention of this emerging zoonotic helminthiasis.