Foodborne parasitic and

Clonorchiasis is caused by the Both infections are common as they may cause duct flatwormClonorchis sinensis. among and other fish-eating (). Opisthorchiasis is caused by mammals (reservoir hosts) in These foodborne trematodes are ? another flatwormOpisthorchis endemic areas. confined to Asia and associated Introduction viverrini. C. sinensis and O. viverrini are with food habits and fish culture classified as carcinogenic agents practices.

Definitive hosts include , human, , and other fish-eating mammals. Adult flukes inhabit the bile ducts of the infected hosts and lay eggs which are dispersed into the environment through Transmission defecation. When eggs reach freshwater, they are ingested by and risk Eating factors specific aquatic from which miracidia hatch. undercooked Miracidia go through different larval stages in the infected fish Lack of intermediate to become cercariae. Definitive host sanitation Cercariae leave the snail and encyst in the (Fluke) and open subcutaneous tissues of various freshwater fish, defecation becoming metacercariae. When consume raw freshwater 2nd intermediate fish, the metacercariae excyst inside the intestine host and migrate back to the , completing the life cycle. Free Humans are infected when they ingest living st metacercariae through infected raw, Use of contaminated 1 intermediate salted and undercooked freshwater fish. water in fish culture host Maturation takes approximately one month.

Acute clonorchiasis/opisthorchiasis may be The WHO-recommended treatment for human scarcely symptomatic in infections of light clonorchiasis and opisthorchiasis is . intensity, but severe (where several For animals, praziquantel can also be used. thousands of are present) can cause and right upper-quadrant pain by Signs and Treatment symptoms the flatworms obstructing the gall bladder. Chronic clonorchiasis/opisthorchiasis from prolonged reinfections can lead to 1. Preventive chemotherapy with a single oral cholangiocarcinoma, a severe and fatal dose of praziquantel form of bile duct cancer. 2. Prevention and control in animals In animals, signs are generally seen only in heavy infections, and are similar to those in • Avoidance of feeding animals with raw humans. Public health freshwater fish prevention and control • Treatment of domestic animals with Individual diagnosis in humans is made praziquantel based on the clinical picture, the individual’s 3. Snail control (especially in farmed fish areas) recall of consuming raw fish, the detection of and typical findings on 4. Water, sanitation and hygiene (WASH) ultrasounds. Confirmation in humans • Improved sanitation and promotion of latrines Detection and animals relies on parasitological, in endemic areas and immunological and molecular techniques. • Reduce faecal contamination of aquaculture diagnosis systems • Provision of safe drinking‐water supply 5. Risk communication proper cooking of freshwater fish and food handling i www.who.int/health-topics/foodborne-trematode-infections