Opisthorchiasis

Flukes are parasitic flatworms that infect various parts of the body (eg, blood vessels, gastrointestinal tract, lungs, liver) depending on the species.

Opisthorchis species are found in Thailand, Laos, Cambodia, Vietnam, Germany, Italy, Belarus, Russia, Kazakhstan, and Ukraine (see Centers for Disease Control and Prevention (CDC): Opisthorchis Infection).

The life cycle of Opisthorchis requires both snails and fish. Dogs, cats, and other fish-eating mammals are also definitive hosts. After ingestion, metacercariae excyst and ascend through the ampulla of Vater into the biliary ducts, where they attach to the mucosa and mature. Adult flukes grow to 5 to 10 mm by 1 to 2 mm (O. viverrini) or 7 to 12 mm by 2 to 3 mm (O. felineus).

Opisthorchiasis resembles clonorchiasis Clonorchiasis Clonorchiasis is infection with the liver fluke Clonorchis sinensis. Infection is usually acquired by eating undercooked freshwater fish. Most infections are asymptomatic, but when present... read more and the development of symptoms depends on worm burden and duration of infection. Most O. viverrini infections remain asymptomatic, with about 5 to 10% of patients presenting with symptoms that include right upper quadrant abdominal pain, indigestion, diarrhea, flatulence, and fatigue. Acute symptoms are more common with O. felineus infection and can include high-grade fever, anorexia, nausea, vomiting, abdominal pain, malaise, myalgia, arthralgia, and urticaria. Symptoms typically begin 10 to 26 days after exposure.

In chronic infection, symptoms may be more severe; hepatomegaly and undernutrition may be present. Rare complications include cholecystitis, cholangitis, and cholangiocarcinoma (bile duct cancer) (1 General references Opisthorchiasis is infection with Opisthorchis viverrini (Southeast Asian liver fluke) or O. felineus (cat liver fluke), which are acquired by eating infected raw or undercooked... read more ). Vietnam veterans who develop cholangiocarcinoma Cholangiocarcinoma Primary liver cancer is usually hepatocellular carcinoma (HCC). The first manifestations of liver cancer are usually nonspecific, delaying the diagnosis. When diagnosed at advanced stages, prognosis... read more may have been infected with Opisthorchis viverrini or Clonorchis sinensis while they served in Southeast Asia (2 General references Opisthorchiasis is infection with Opisthorchis viverrini (Southeast Asian liver fluke) or O. felineus (cat liver fluke), which are acquired by eating infected raw or undercooked... read more ).

Diagnosis of opisthorchiasis is by finding eggs in the feces. Ultrasonography, CT, MRI, cholangiography, or endoscopic retrograde cholangiopancreatography (ERCP) may show biliary tract abnormalities.

The treatment of choice for opisthorchiasis is one of the following:

Infection can be prevented by cooking freshwater fish.

See also the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) information on opisthorchiasis.