Buy the Book PDA Download

Update Me E-mail alerts The Merck Manual Minute

Print This Topic Email This Topic

Clonorchiasis is infection with the liver fluke Clonorchis sinensis. Infection is through undercooked freshwater fish. Symptoms include fever, chills, epigastric pain, tender hepatomegaly, diarrhea, and mild jaundice. Diagnosis is by identifying eggs in the feces or duodenal contents or occasionally by percutaneous transhepatic cholangiography. Treatment is with praziquantel or albendazole.

Adult C. sinensis worms live in the bile ducts. Eggs are passed in the stool and ingested by snails. Cercariae released from infected snails subsequently infect a variety of freshwater fish. Humans become infected by eating raw, dried, salted, or pickled fish containing encysted metacercariae. The latter are released in the duodenum, enter the common bile duct, and migrate to smaller intrahepatic ducts (or occasionally the gallbladder and pancreatic ducts), where they mature into adult worms in about 1 mo. The adults may live ≥ 20 yr.

Clonorchis is endemic in the Far East, especially in Korea, Japan, Taiwan, and southern China, and infection occurs elsewhere among immigrants and those eating fish imported from endemic areas.

Light infections are usually asymptomatic. Heavier infections can cause fever, chills, epigastric pain, tender hepatomegaly, mild jaundice, and eosinophilia. Later, diarrhea may occur. Chronic cholangitis in heavy infections may progress to atrophy of liver parenchyma, portal fibrosis, and cirrhosis. Jaundice may occur if a mass of flukes obstructs the biliary tree. Other complications include suppurative cholangitis, chronic pancreatitis, and, late in the course, cholangiocarcinoma.

Diagnosis is by finding eggs in the feces or duodenal contents. The eggs are difficult to distinguish from those of Metagonimus , Heterophyes, and Opisthorchis. Other tests are nondiagnostic but may be abnormal; alkaline phosphatase, bilirubin, and eosinophil counts may be elevated. A plain abdominal x-ray occasionally shows intrahepatic calcification. Hepatic ultrasound may show ductal irregularities and evidence of scarring.

Treatment is with praziquantel Some Trade Names
BILTRICIDE
Click for Drug Monograph
25 mg/kg po tid for 1 day or albendazole Some Trade Names
ALBENZA
Click for Drug Monograph
10 mg/kg po once/day for 7 days. Biliary obstruction may require surgery. Freshwater fish from endemic waters should be thoroughly cooked and not eaten raw, pickled, or wine-soaked.

Last full review/revision November 2005

Content last modified November 2005