Clonorchis sinensis
by
Albert Teo
&
Doug Mandler
Taxonomy
Kingdom
Phylum
Class
Order
Family
Genus
Species
: Animalia
: Platyhelminthes
: Trematoda
: Opisthorchiida
: Opisthorchiidae
: Clonorchis
: C. sinensis
*A quick note – Clonorchis sinensis was given its own genus by Looss
because of the parasites branched testes as apposed to the
Opisthorchis lobed testes
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 in humans.
Question!

Why is Clonorchis sinensis known as the
‘Chinese/Oriental’ liver fluke?

Because out of the 601 million, 570 million are
Chinese and Taiwanese. It is found predominantly
in the regions of the world that raw fish is a delicacy.
Geographic Distribution





Japan
Korea
China
Taiwan
Vietnam
Definitive Hosts


Any fish eating mammals
Humans






Humans are an incidental host, the natural definitive hosts are
those that fallow in this list
Pigs
Dogs
Cats
Rats
Camels
Intermediate Hosts





Snails
Fish
First intermediate host must always be a snail,
mainly Parafossarulus manchouricus
Second intermediate host is usually a fish
12 species of fish are mainly responsible for
passing the infection to humans
Life Cycle
A Closer Look At the Life Cycle




Egg of C. sinensis that contains miracidium floats in
fresh water until it is ingested by a snail
It will then develop into a sporocyst, which houses the
asexual reproduction of redia
Redia will themselves asexually reproduce to form the
cercariae
Cercariae are the free-swimming form of the parasites
that enables the second intermediate host to be infected
Critical Thinking

The asexual reproduction of C. sinensis enables
an exponential multiplication of cercaria
individuals from one miracidium. How can this
aid C. sinensis?
- This aids the Clonorchis in reproduction,
because it enables the miracidium to captilatize
on one chance occasion of passively being eaten
by a snail before the egg dies.
Life Cycle cont.



The cercariae will then actively bore themselves
out of the snail
It will then seek out a fish, and bore into the
skin/flesh of its target
Once inside the second intermediate host, the
cercariae will become a metacercarial cyst
Question

Why would the cercariae want to encyst
themselves in the flesh/skin of the second
intermediate host?
- The metacercarial cysts are acid-resistant, thus
ensuring that they are protected from the acidic
environment of the stomach after ingestion
Life Cycle cont.




Once in the small intestine, the metacercariae
will excyst
They will then navigate to the liver
Once at the liver, the Clonorchis will achieve its
sexual maturity stage
The hemaphroditic adults produce eggs every 1
- 30 seconds
Picture of C. sinensis
Pictures cont.
Sites of Infection



Infection occurs in the liver
Bile duct is preferred site
The parasite feeds on the bile
Pathogenesis/Clinical Signs







Infection is usually asymptomatic; however, heavy
infestation may cause biliary obstruction
Loss of appetite
Nausea
Diarrhea
The sensation of abdominal pressure or pain
Rarely, bile duct obstruction may produce jaundice
followed by cirrhosis
Enlargement and tenderness of the liver
Pathogenesis/Clinical Signs
Continued



Could result in the common bile duct and/or
gall bladder to explode within the human body
May cause adenocarninoma of the bile ducts
(cholangiocarcinoma)
Loss of fat digestion (severe infestation)
Diagnosis



Fecal smears and examinations
Duodenal aspirate
Adult flukes can also be recovered at surgery
Treatment

Drugs:
Praziquantel (most effective)
 Albendazole

Control Maneuvers



Physical inactivation: Sensitive to heating at
56°C for 30 minutes for all infectious stages
Survival outside host: Sensitive to freezing
Susceptible to disinfectants: All infective
stages are susceptible to 1% sodium
hypochlorite
Other Control Measures?

What other control measures can be used to
curb the prevalence of this parasite?
-
Sanitation
Human feces as fertilizer
Think oral-fecal contamination measures
-
FYI
BE WARNED!

Metacercariae can remain viable even after the
fish has been pickled, salted, dried, or smoked
Works Cited




http://www.phac-aspc.gc.ca/msds-ftss/msds34e.html
http://animaldiversity.ummz.umich.edu/site/accounts/
information/Clonorchis_sinensis.html
http://www.kstate.edu/parasitology/625tutorials/Clonor02.html
http://www.kstate.edu/parasitology/625tutorials/Trematodes08.html

http://en.wikipedia.org/wiki/Clonorchis_sinens
is

Text Book