#parasaite

1. 10th LECTURE

2. HETEROPHYIASIS

3. Causal Agent
Heterophyiasis is a parasitic disease caused
by Heterophyes sp. (human intestinal fluke
parasites)
Systematic position
Phylum: Platyhelminthes
Class: Trematoda
Order: Digenea
Genus: Heterophyes

4. Geographical distribution
Occurs in Egypt, Sudan, Brazil, Spain,
Turkey, Iran, India, and Russia
Common in North Africa, Asia Minor,
Korea, China, Japan, Taiwan, and the
Philippines.
In the Middle East and Far East

5. Heterophyiasis
 In Egypt, it is widely distributed in regions near to the
seashore or brackish water (northern lakes).
 Mostly infects fish-eating mammals and birds.
 Human can be infected by this parasite as well.

6. Heterophyes sp. (Intestinal fluke)

7. Heterophyes sp. is a parasite of the small
intestine
of fish-eating mammals and birds.
• It is a tiny parasite with a pear-shaped body.
• Body is covered with spines.
• The oral sucker is smaller than the ventral
sucker.
• It has a large genital sucker (behind the ventral

8. Life cycle
 Heterophyes eggs are egested in stool of the final
host (1).
 Eggs are eaten by the 1st intermediate host ( Pirenella
conica), eggs then hatch in the digestive tract of the
snail.
 Asexual reproduction occurs in Pirenella sp.
(sporocyst, mother redia and daughter redia) (2).
 Cercariae then escape from the 1st intermediate host

9.  Cercariae encyst in Mugil ( Mugil cephalus )
muscles and form metacercariae. (4)
 When the final host eats raw fish, metacercariae
excyst and reach the small intestine -
intervillous spaces- (the final destination). (5)

11. Heterophyiasis
 Infective stage: Metacercaria.
 Infection route: Oral.
 Intermediate host(s): Two (snail & fish).
 Mode of Infection : Eating of undercooked infected
fish.
 Infection site: intervillous spaces of small intestine.

12. Clinical Features
Because Heterophyes sp. invades the intervillous spaces
of the small intestine, it causes:
 Mechanical and toxic damage to the surrounding
region.
 Abdominal pain and diarrhea can be happened in the
highly infected people.
 In the massive infection cases, blood and mucus can
be seen in the patient‘s stool.

13. Clinical Features Con.
 Deeply embedded worms in the mucosa may pass
eggs into circulation and the eggs can reach different
organs & tissues leading to health problems.
 Migration of the eggs to the heart: Results in
potentially fatal myocardial & valvular damage.

14. Laboratory Diagnosis
 Microscopic identification of eggs
 Eggs can be recovered in the stools

15. Control & Prevention
 Avoid defecation in water.
 Avoid eating insufficiently cooked or salted fishes.

16. Learning outcomes
• By the end of the lecture, you should be able to:
1- Mention Causal agent of Heterophyiasis.
2- Mention systematic position of Heterophyes sp.
3- Mention geographic distribution of heterophyiasis.
4- Enumerate intermediate and definitive hosts of Heterophyes
sp.
6- Explain life cycle of Heterophyes sp.
7- Mention habitat of Heterophyes sp.
8- Mention mode of infection by Heterophyes sp.
9- Mention pathology and clinical features of heterophyiasis.
10- Diagnose heterophyiasis.
11- Mention disease control strategies

17. Suggested Reading
• https://phil.cdc.gov/phil/details.asp?pid=3397
•
https://en.wikipedia.org/wiki/Heterophyes_heteroph
yes
• Chiodini, P.L.; Moody, A.H. and Manser,D.W.
(2001): Atlas
of Medical Helminthology and Protozoology. 4th ed.
Churchill Livingstone, P. 34.