“CHINESE LIVER FLUKE”

Clonorchis sinensis

Geographic distributionEndemic(native) areas are in Asia including Korea, China, Taiwan, and Vietnam. There have been cases in the United States in Asian immigrants due to the ingestion of undercooked freshwater fish containing metacercariae(infective cyst stage).

Hosts

Definitive host: humans, fish eating vertebrates

1st Intermediate host: some sort of snail

2nd Intermediate host: freshwater fish(over 100 species), common one is the grass carp

Morphology Adults 8-25 mm long and 1.5 to 5

mm wide

Weak muscularity, lack spines

Have oral sucker at anterior end

Life Cycle

rediae

cercariae

Metacercariae(on fish), pg 290 book

Epidemiology

A problem in Asia where raw fish is a delicacy

Many fish farms where fish are fed with human and animal feces, thus promoting the C. sinensis lifecycle

Metacercarie will survive pickling, drying, smoking, and salting so people can be infected where this imported fish is consumed

Dogs and cats also contaminate water supplies with feces

Symptoms

Fever Chills Stomach pains Jaundice(not common) Digestive problems

Pathology

Causes clonorchisasis C. sinensis generally only inhabit 2nd

order bile ducts, 1st order to small Cause production of excess mucus,

erosion of epithelial lining, and surplus epithelial cell growth

Duct inflammation and necrosis or atrophy of adjacent liver cells

Deformation of ducts leads to gradual thickening and possible closure of duct

Infiltrating pockets of eggs become surrounded by granulomas and interfere with liver function

Advanced clonorchiasis can cause cancer of the bile duct

Diagnosis and Treatment

Diagnosis is based on the look of eggs recovered from feces.

Liver abnormalities in native areas or populations are a good clue for clonorchiasis, must be careful to rule out other liver diseases

Tissue sample to look for adult flukes is also used

Treatment Drug used is called Praziquantel which kills the

flukes in the intestine Side effects include: headaches, dizziness,

drowsiness, fever, nausea, stomach pain

Prevention

Thoroughly cook fish before consuming

Food pickled, dried, or pickled from endemic areas

eggs