Food Borne Trematodes. endemic in Asian Countries.

1. Clonorchis sinensis
 Kingdom : Animalia
 Phylum : Platyhelminthes
 Class : Trematoda
 Order : Opisthorchiida
 Family : Opisthorchiidae
 Genus : Clonorchis
 Species : C. sinensis

2. Brief Introduction to C. sinensis
 “Oriental Liver Fluke”. Food born parasite
 601 million people are currently at risk, 570 million of
which live in China and Taiwan.
 An estimated 30 million people are infected with C.sinensis.
 The parasite may live up to 45 years in humans.

3. Epidemiology
 Geographical distribution:
 Asia only
 Mainland China, highly endemic in south eastern China,
Japan , Taiwan, Korea, Vietnam and eastern part of Russia
 Reports outside of Asia are important (imported cases)

4. Epi cont……
 Clonorchiasis is endemic where there is poor sanitation.
 The right snail host.
 The right fish (cyprinoid fish) as the second intermediate
host.
 A population who eats raw, poorly pickled, smoked, dried
or salted freshwater fish.

5. Geographic Distribution
• Japan
• Korea
• China
• Taiwan
• Vietnam

6. Hosts
Definitive
• Fish eating mammals
• Humans are the principal definitive host, but
dogs and other fish-eating canines act as
reservoir hosts.
Intermediate Hosts
• Snails(1st)- Parafossarulus manchouricus
• Fish(2nd)- 12 species of fish are capable of
passing the infection to human.

7. Transmission route
 Source of infection: patients, infected reservoir hosts: cats,
dogs, mice, pigs
 The infection is acquired by eating raw or inadequately
cooked freshwater fish or shrimp which are previously
infected.
 Susceptibility: human is generally susceptive, related with
the dietary habits

8. Life cycle

9. Pathogenesis
 Worms mechanical stimulation proliferate inflammatory
reaction in the biliary epithelium.
 The wall of the bile ducts thickened ,fibrous tissue around
the bile duct, and worm obstruction cause cholestasis.
 When bacteria infection occur, cause cholecystitis,
cholangeitis, sometimes cholelithiasis happens.

10. Pathology
 Intrahepatic bile ducts expansion, hepatomegaly, necrosis
of liver tissue
 Continuous severe infection may cause liver cirrhosis.
 Persistent Cholestasis cause biliary liver cirrhosis.
 Associate with cholangiocarcinoma and hepatic
carcinoma.

11. Clinical Manifestation
 Incubation period: 1-2 months
 In mild clonorchis sinensis infections are asymptomatic, only
eggs are found in the feces
 Acute symptoms appear in heavy infection: chill, high fever,
slight jaundice, hepatomegaly, eosinophilia, other patients
have splenomegaly, and chronic stage develops.
 Continuous re-infection: cirrhosis and portal hypertension. It
may cause stunted growth in children .

12. Diagnosis
 Patient History:
 Living in or come from the endemic area.
 Eating raw or inadequately cooked
freshwater fish and shrimp
 Clinical sign:
 Gastrointestinal symptoms, hepatomegaly,
neurasthenia, cholangoitis, cholecystitis, etc.

13. Diagnosis
 Laboratory findings:
Discovery of characteristic eggs in faeces or aspirated bile.
 Several serological tests.
 Intradermal allergic tests.
 Blood routine test: eosinophilia, anaemia in severe
infection.

14. Prevention and control
Cut off the route of transmission:
 Avoid eating inadequately cooked freshwater fish and
shrimp
 Sanitary disposal of the excreta
 Avoid of drinking contaminated water
 Control of snails.

15. Treatment
 Treat the patients and domestic animal(cats and dogs, etc.)
at the same time.
 Drugs:
 Praziquantel (most effective)
 Albendazole
 Surgical intervention may become necessary in cases with
obstructive jaundice.

16. Beware!!!
 Metacercariae can remain viable even after the fish has
been pickled, salted, dried, or smoked.