1. Schistosoma Parasites
Called Blood Flukes
Adult Flukes live in blood vessels of infected Humans
S.haematobium
S.mansoni
S.japonicum
D.H: Man
R.H: None
D.H: Man
R.H: Rodent, Monkeys
D.H: Man
R.H: Domestic animals
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2. Definitive Host Habitat Man Blood vessels
Inferior mesenteric plexus of veins
Superior & Inferior mesenteric plexus of veins
Vesical & pelvic plexus of veins
Where adult S.haematobium live
Where adult S.mansoni live
Where adult S.japonicum live
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3. Schistosoma differs from other trematodes in:
Has separate sexes.
Lives in blood.
Has non-operculated eggs.
Has no Redia stage.
Has no encysted metacercaria.
Common species affecting man:
S. mansoni, S. haematobium,
S. japonicum, S. intercalatum and
S. mekongi.
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4. Recent discovery:
Theodore Bilharz: discovered the worms and their relation to the disease in 1851 in Cairo.
Manson: (1893):
Discovered that there are 2 different species of the parasite in Egypt.
Leiper ( ):
Discovered the relation to snail intermediate hosts and the mode of infection.
McDonagh (1918)
Used tartar emetic for treatment
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5. Adult Morphology Sexes: separate Female: cylindrical
Male: flattened, folded (gynaecophoric canal).
Suckers: oral & ventral (smaller in females).
Digestive system:
No muscular Pharynx Intestinal ceaca reunite in a single caecum.
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6. Male 10x 1 mm 8x1 mm 15xo.5 mm Fine tubercles course tubercles
S. haematobium
S. mansoni
S. japonicum
10x 1 mm
8x1 mm
15xo.5 mm
3-5 testes in a line
6-9 testes in cluster
6-8 testes in a line
Fine tubercles
course tubercles
No tubercles
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7. Female S. haematobium S. japonicum 20x0.2 mm 14x0.15 mm 26x0.3 mm
S. mansoni
S. japonicum
20x0.2 mm
14x0.15 mm
26x0.3 mm
Ovary post 1/3
ovary ant. 1/3
Ovary in the middle
Vit. gl. post 1/3
vit. gl post 2/3
Vit. gl. in post 1/2
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8. translucent, non operculated Mature embryo (miracidium)
Egg
S. haematobium
S. mansoni
S. japonicum
In urine
In stool
Size
140x 60 
150x60 
85x65 
Shape
Oval
terminal spine
Lateral spine
Ovoid
Minute knob
Shell
translucent, non operculated
Content
Mature embryo (miracidium)
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9. Miracidium Snail I. H Bulinus truncatus Biomphalaria alexandrina
S. Haematobium
Bulinus truncatus
S. mansoni
Biomphalaria alexandrina
S. japonicum
Oncomelania
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10. Infective stage (Cercaria):
Formed of body and forked tail (furcocercous)
5-6 pairs of penetration glands.
Skin penetration is aided by:
1-Proteolytic enzymes.
2-Surface tension of drying
water.
3-Movement of the tail
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11. Schistosomulum reaches circulation
Worms mate in the liver
Worms in their habitat
Female lays eggs
Schistosomulum reaches circulation
Miracidium infects snail i.h.
Eggs in urine or stools
Infection in contaminated water
Cercarial shedding
Miracidia hatch
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12. Life cycle
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13. Development of Schistosoma inside the body of infected human
Aorta II
Systemic circulation
Venous circulation
Liver
Schistosomula ♀
Vesical plexus ♂
S.haematobium I
Portal vein
Inf. mesenteric plexus
Cercariae penetrates human skin
III
S.mansoni IV
Direction of venous blood flow
In urine or stool
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14. Pathogenesis and Clinical Picture
There are 4 progressive stages:
I- Stage of invasion
(1-4 days)
Local dermatitis, irritation.
Papular rash.
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15. urticaria, fever, headache, muscle pain.
II- Stage of migration
(3-4 weeks)
By schistosomula
Metabolic products: toxic and allergic manifestations as
urticaria, fever, headache, muscle pain.
In the lung: verminous pneumonitis, minute haemorrhage
cough, haemoptysis.
In the liver: enlarged and tender.
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16. III- Stage of egg deposition and extrusion
(acute stage: 1-2 month)
A- Eggs are deposited in the venous plexus
The patient may complain of:
Generalized malaise, fever,
rigors, urticaria, abdominal pain
and liver tenderness.
Urticaria
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17. The patient suffers from:
Katayama Syndrome
Occurs mainly in S.japonicum infection
Due to:
1- ♀lays large number of eggs
2- greater proximity to the liver
Soluble egg antigens are released in blood stream
immune complex
Circulate
Blood vessel
antibodies
Deposited in the tissues
Tissue damage
The patient suffers from:
Fever, chills, diarrhoea, generalized lymphadenopathy
Thus also called acute toxoemic schistosomiasis
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18. B- Stage of egg extrusion:
1-Pressure within the venule
2-Effect of the spine
Eggs escape from the veins to the perivascular tissue due to:
3-oozing lytic secretion of the miracidium within the egg
Damage & haemorrhage
S.haematobium
S.mansoni & S.japonicum
In vesical & pelvic plexus of veins
In mesenteric plexus of veins
Egg extruded
Egg extruded
Bladder wall
Intestinal wall
Terminal haematuria, frequency of micturition, burning pain
Dysentery with blood and mucus in stool
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19. IV- Stage of tissue reaction (chronic stage)
(months – years)
Shell & miracidial antigens
Occurs around Schistosoma eggs deposited in various tissues.
Granuloma formation in tissue
Granuloma develops
Attract inflammatory cells
Deposition of fibrous tissue
Damage of affected organ and its fibrosis
miracidium
Inflammatory cells
Egg shell
Delayed-type hypersensitivity
Loss of its function
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20. Cancer bladder may occur
In normal condition
In S.haematobium infection
hydronephrosis
Normal mucosa of colon
hydroureter
Fibrous tissue
Egg trapped in bladder wall
Polyps in the colon in S.mansoni infection
Stone formation
Cancer bladder may occur
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21. IV- Stage of tissue reaction (chronic stage)
In S.haematobium infection
In S.mansoni infection
Eggs fail to fix to venule wall are swept by blood
Eggs fail to fix to venule wall are swept by blood 3 3 2
Eggs trapped in Intestinal wall 2
Eggs trapped in Bladder wall
Eggs extruded in urine 1
Eggs extruded in stool 1
Cause Embolic lesions
Cause Embolic lesions
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22. Embolic Lesions in the Liver
Portal hypertension
Hepatosplenomegaly
Oesophageal varices
Ascites.
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23. Embolic Lesions in the lung
Bilharzial cor-pulmonale
Pulmonary hypertension
In Schistosoma infection
In Normal condition
Trapped eggs
Dilated right ventricle
Thickened wall
Enlarged right ventricle
Cor-pulmonale = right-sided heart failure
Means: enlargement of right ventricle due to high blood pressure in the arteries of the lung
Embolic lesions may occur in any other organ.
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24. Diagnosis of Schistosomiasis
Clinically
Laboratory
Radiological imaging
Endoscopy
(suggestive)
1- History of contact with infected water.
1- Detection of eggs in urine or stool
2- Clinical picture according to stage of infection.
2- Blood examination
3- Serological tests
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25. I- Laboratory Diagnosis
1- Direct parasitological methods:
- Detection of S.haematobium eggs in urine.
- Detection of S.mansoni eggs in stool by direct smear method or by concentration method.
- Test for viability.
- Kato thick faecal smear: for egg counting to assess the intensity of infection
- Rectal swab S:
140X60 µ
150X60 µ S:
Terminal spine
Oval, thin shell
Lateral spine C:
Translucent C:
Miracidium
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26. I- Laboratory Diagnosis
2- Blood examination:
1- Egg extrusion
Iron deficiency anaemia
Anaemia due to
2- Hypersplenism
Haemolytic anaemia
Eosinophilia, leucocytosis.
3- Serological Tests:
(Immunodiagnostic Tests)
Detection of anti-Schistosoma antibodies or antigen in patient’s serum
a- IHAT (Indirect Haemagglutination test)
Sensitized sheep RBCs
Latex particles
+ve
-ve
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27. b- ELISA (Enzyme-linked immunosorbent assay)
Coating with Schisto Ag
Patient’s serum
Ab linked to enzyme
substrate
Ab detected
wash
wash
wash
Coating with anti-Schisto MAb
Patient’s serum
Ab linked to enzyme
substrate
Ag detected
wash
wash
wash
c- IFAT (Indirect Fluorescent Antibody test)
Ab detected
Patient serum
Schisto Ag
wash
wash
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28. II- Radiological imaging
S.haematobium infection
S.mansoni infection
Calcified bladder with hydroureter
Stenosed ureters and hydronephrosis
Intestinal affection
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29. المناظير III- Endoscopy
Cystoscopy in S.haematobium
Colonoscopy, sigmoidoscopy in S.mansoni
Done in chronic cases to detect lesions and take biopsies
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30. RAAFAT T. MOHAMED

31. Praziquantel (Biltricide): For all schistosome species.
Treatment
Praziquantel (Biltricide):
For all schistosome species.
Dose:40 mg/kg single oral dose
Oxamniquine (vancil):
For S. mansoni
Dose: 30 mg/kg for 2 days
Metriphonate:
For S. haematobium only.
Dose: 10mg/kg every 2 weeks for 3 doses.
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32. Prevention and Control
- Mass treatment.
- Health Education.
- Snail control:
Physical methods
Biological methods
Chemical methods X
Balanites aegyptica
Copper sulphate
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33. Cercarial Dermatitis (Bather’s itch)
A condition that occurs due to penetration of cercariae of non-human species of schistosomes the skin of man.
Cercariae cannot go beyond the germinal layer.
Clinical picture:
Dermatitis, itching, oedema and secondary bacterial infection.
Treatment:
Antipruritics, antihistamincs,
antibiotics.
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34. Multiple Choice Questions
The major cause of morbidity in schistosomiasis is:
a- Migration of adult worms against blood stream.
b- Maturation of worms to adult stage in the liver.
c- Occurrence of Embolic lesions.
d- Deposition of eggs in tissues.
Kato technique is used to diagnose:
a- Paragonimiasis
b- Schistosomiasis mansoni
c- Schistosomiasis haematobium
d- Fascioliasis
Bather’s itch occurs frequently with:
a- S.haematobium
b- S.mansoni
b- S.japonicum
d- non human schistosomes
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35. Multiple Choice Questions
Katayama syndrome:
a- occurs most frequently in S.haematobium infection.
b- occurs most frequently in S.mansoni infection.
c- occurs most frequently in S.japonicum infection.
d- occurs in chronic schistosomiasis.
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36. Give reasons for
Occurrence of terminal haematuria in S.haematobium infection
Terminal haematuria is due to active deposition of eggs by adult female S. haematobium in vesical venous plexuses.
Eggs escape to the perivascular tissue and become extruded to the lumen of the urinary bladder.
Powerful contraction of the bladder at the end of micturition (to squeeze the last drops of urine) leads to haemorrhage (terminal haematuria).
Egg passes lumen of urinary bladder
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37. Occurrence of Bilharzial cor-pulmonale in schistosomiasis
Give reasons for
Occurrence of Bilharzial cor-pulmonale in schistosomiasis
Many eggs that fail to be fixed to walls of venules are swept by blood to reach various organs
as the lungs where they form granulomas and fibrosis with obliteration of flow resulting in pulmonary hypertension and right-sided heart failure.
Swept by blood
Heart
Lung
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