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[Opisthorchis felineus] [Opisthorchis viverrini]

Adult of O. viverrini. Image courtesy of the Web Atlas of Medical Parasitology and the Korean Society for Parasitology.

Adult Opisthorchis viverrini stained with carmine.

 Eggs of O. viverrini in an unstained wet mount of concentrated stool. Images taken at 400x magnification.

Egg of O. viverrini in an unstained wet mount of concentrated stool. Image taken at 400x magnification.

Causal Agents

Trematodes (flukes) Opisthorchis viverrini (Southeast Asian liver fluke) and O. felineus (cat liver fluke).

Life Cycle

Life cycle of Opisthorchiasis

The adult flukes deposit fully developed eggs that are passed in the fecesThe number 1. After ingestion by a suitable snail (first intermediate host)The number 2, the eggs release miracidiaThe number 2a , which undergo in the snail several developmental stages (sporocystsThe number 2b, rediaeThe number 2c, cercariaeThe number 2d ). Cercariae are released from the snailThe number 3 and penetrate freshwater fish (second intermediate host), encysting as metacercariae in the muscles or under the scalesThe number 4. The mammalian definitive host (cats, dogs, and various fish-eating mammals including humans) become infected by ingesting undercooked fish containing metacercariae. After ingestion, the metacercariae excyst in the duodenumThe number 5 and ascend through the ampulla of Vater into the biliary ducts, where they attach and develop into adults, which lay eggs after 3 to 4 weeksThe number 6. The adult flukes (O. viverrini: 5 mm to 10 mm by 1 mm to 2 mm; O. felineus: 7 mm to 12 mm by 2 mm to 3 mm) reside in the biliary and pancreatic ducts of the mammalian host, where they attach to the mucosa.

Geographic Distribution

Opisthorchis viverrini is found mainly in northeast Thailand, Laos, and Kampuchea. Opisthorchis felineus is found mainly in Europe and Asia, including the former Soviet Union.

Clinical Presentation

Most infections are asymptomatic. In mild cases, manifestations include dyspepsia, abdominal pain, diarrhea or constipation. With infections of longer duration, the symptoms can be more severe, and hepatomegaly and malnutrition may be present. In rare cases, cholangitis, cholecystitis, and chlolangiocarcinoma may develop. In addition, infections due to Opisthorchis felineus may present an acute phase resembling Katayama fever (schistosomiasis), with fever, facial edema, lymphadenopathy, arthralgias, rash, and eosinophilia. Chronic forms of Opisthorchis felineus infections present the same manifestations as Opisthorchis viverrini, with in addition involvement of the pancreatic ducts.

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  • Page last reviewed November 29, 2013
  • Page last updated November 29, 2013
  • Content source: Global Health - Division of Parasitic Diseases and Malaria
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