1. Schistosomiasis
Dr. Gamal Allam

2. Learning outcomes By the end of the lecture, you should be able to:
1- Mention Causal Agent of schistosomiasis.
2- Mention systematic position of Schistosoma spp.
3- Mention geographic distribution of schistosomiasis.
4- Enumerate Intermediate, Definitive and Reservoir hosts of Schistosoma spp.
6- Explain life cycle of Schistosoma spp.
7- Mention habitat of Schistosoma spp.
8- Mention mode of infection by Schistosoma spp.
9- Mention pathology and clinical features of schistosomiasis.
10- Diagnose schistosomiasis.
11- Mention prevention and control means of schistosomiasis
Dr. Gamal Allam

3. Causal Agents Schistosomiasis is caused by digenetic blood trematodes.
Three main species infecting humans:
Schistosoma haematobium
Schistosoma mansoni
Schistosoma japonicum
Dr. Gamal Allam

4. Systematic position Phylum: Platyhelminthes Class: Termatoda
Genus: Schistosoma (S.)
5 species of can infect human:
S. haematobium
S. mansoni
S. japonicum
S. mekongi
S. intercalatum
Dr. Gamal Allam

5. Geographic Distribution
Schistosoma mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East.
Schistosoma haematobium in Africa and the Middle East.
Schistosoma japonicum in the Far East. 
Dr. Gamal Allam

6. Geographic Distribution…… cont.
Schistosoma mansoni
S. haematobium
Dr. Gamal Allam

7. Morphology of Schistosoma
Stages Adult, Egg, Miracidium, Sporocyst, Cercaria, Schistosomule
Dr. Gamal Allam

8. Adult Worm Separate sex( male and female worms)
The male has a gynecophoric canal in which it carries the female during the life cycle.
10-20 mm long.
Dr. Gamal Allam

9. Egg S. haematobium S. mansoni S. japonicum
Oval (S. haematobium & S. mansoni) or Round (S. japonicum)
Translucent
Contains mature miracidium
With terminal spine (S. haematobium), lateral spine (S. mansoni), or rudimentary lateral spine (S. japonicum)
S. haematobium S. mansoni S. japonicum
( x 40-70µm) ( x 45-70µm) ( x 50-70µm)
Dr. Gamal Allam

10. Miracidium
Pyriform
Ciliated
~200µm long
Dr. Gamal Allam

11. Sporocyst
Sac- like
Contain germinal cells masses
Dr. Gamal Allam

12. Cercaria Has a body and tail Has furcocercous ( forked) tail
µm long
Dr. Gamal Allam

13. Life Cycle
In human(Definitive host), male & female mature and pair up in the liver.
The couple migrate against the blood stream direction to favoured site where female deposit eggs: mainly mesenteric venules of large bowel & rectum (S. mansoni), mesenteric venules of small intestine (S. japonicum), or pelvic and vesical venous plexus (S. haematobium).
About 50% of deposited eggs passed out of body and 50% trapped in tissues.
Eggs are released with feces (S. mansoni & S. japonicum) or urine (S. haematobium) .
Dr. Gamal Allam

14. Life Cycle…. cont
In fresh water and under optimal conditions the eggs hatch and release miracidia, which swim and penetrate specific snail intermediate hosts: Biomphalaria sp. (S. mansoni), Bulinus sp. (S. haematobium), or Oncomelania sp. (S. japonicum)
In the snail (intermediate host) asexual replication occur including 2 generations of sporocysts and the production of cercariae.
Upon release from the snail, cercariae (the infective stage) swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae (Skin schistosomulae).
Dr. Gamal Allam

15. Life Cycle…. cont
The schistosomulae migrate through blood vessel to the lungs (lung schistosomulae ) and then to the liver which mature to adult worm.
Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species as mentioned previously .
The females deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S. mansoni and S. japonicum) and of the bladder and ureters (S. haematobium), and are eliminated with feces or urine, respectively .
Dr. Gamal Allam

16. Life Cycle
Dr. Gamal Allam

17. Intermediate and Reservoir hosts
Intermediate host
Reservoir hosts
S. mansoni
Biomphalaria
rodents and monkeys
S. haematobium
Bulinus
S. japonicum
Oncomelania
dogs, cats, rodents, pigs, and goats.
Dr. Gamal Allam

18. Clinical Features
Acute schistosomiasis (Katayama's fever) occur weeks after the initial infection, especially by S. mansoni and S. japonicum. Manifestations include:
fever,
cough,
abdominal pain and diarrhea,
hepatospenomegaly,
eosinophilia.
Dr. Gamal Allam

19. Clinical Features…..cont.
Chronic infection cause granulomatous reactions and fibrosis in the affected organs, which may result in manifestations that include:
colonic polyposis with bloody diarrhea (S. mansoni).
portal hypertension with hematemesis and splenomegaly (S. mansoni, S. japonicum);
cystitis and ureteritis with hematuria, which can progress to bladder cancer (S. haematobium).
pulmonary hypertension (S. mansoni, S. japonicum)
glomerulonephritis (S. haematobium).
may central nervous system lesions.
Dr. Gamal Allam

20. Hepatic granuloma
Dr. Gamal Allam

21. Clinical Features…..cont.
Dr. Gamal Allam

22. Laboratory Diagnosis
Microscopic identification of eggs in stool or urine is the most practical method for diagnosis.
Stool examination should be performed when infection with S. mansoni or S. japonicum is suspected.
Urine examination should be performed if S. haematobium is suspected.
Dr. Gamal Allam

23. Eggs of Schistosoma spp.
S. haematobium
Schistosoma mansoni
Dr. Gamal Allam

24. Schistosoma japonicum eggs
Dr. Gamal Allam

25. Prevention and Control
Avoidance of wading, bathing, swimming in or drinking polluted water.
Wearing protective clothes (gloves, boots ).
Quick and through drying of exposed skins.
Abstinence from defecation and micturation in water canals.
Mass treatment of all infected cases.
Control of Snail ( intermediate host) through:
Physical methods : changing the suitable environmental conditions like canal coverage
Biological methods :introduction of natural enemies as competitive snails or fish
Chemical methods using molluscicides eg: copper sulphate
Dr. Gamal Allam

26. 1-Infective stage of Schistosoma is Furcocercus cercaria 2- Bulinus trancatus snail is the intermediate host of Schistosoma mansoni 3- One of the following parasite live in blood
Dr. Gamal Allam

27. Thank You
Dr. Gamal Allam