1. Schistosoma Parasites
• Scistosomes are NOT hermaphrodite
(sexes are separate).
• Male is flat and female is cylindrical.
• Eggs are NOT operculated but have a spine.
• Inside the snail: NO redia stage.
• Infective stage: Cercaria NOT encysted metacercaria.
• Mode of infection: skin penetration NOT by ingestion.
Introduction
Fasciola
Paragonimus
Heterophyes
S.mansoni
S.haematobium
miracidium
sporocyst
redia
Inside snail
operculum
spine
Flat ♂
Cylindrical ♀
Cercaria

2. Schistosoma causes Schistosomiasis
Geographical distribution:
Schistosoma mansoni
Distribution
Schistosoma haematobium
Distribution

3. Schistosoma japonicum Distribution
Present in the Far East

4. Definitive Host Man Habitat
Superior & Inferior
mesenteric plexus of
veins
Vesical & pelvic
plexus of veins
Where adult
S.mansoni live
Where adult
S.haematobium live
Blood vessels
Thus Schistosomes are
called Blood flukes
Inferior
mesenteric
plexus of
veins
Where adult
S.japonicum live

5. Life Cycle
Infected
human
Egg in
urine
miracidium
B.truncatus
B.alexandrina
Intermediate host
Furcocercous
cercaria
Egg in
stoolCercaria
penetrate
human skin
Fresh water
Definitive host
S.haematobium S.mansoni
Infective stage
Mode of infection
Diagnostic
stage

6. Diagnostic Stage
S.haematobium egg in urine S.mansoni egg in stool
Size:
Shape:
Colour:
Content:
140X60 µ 150X60 µ
Oval, thin shell
Terminal spine Lateral spine
Translucent
Miracidium

7. Mode of Infection
Skin penetration by furcocercous cercaria from
contaminated canal water.
Aided by:
- Surface tension of drying
droplets of water.
- Proteolytic enzymes secreted by
penetration glands.
- Strong lashing movement of the tail
pressing the body of the cercaria into the skin.

8. Development of Schistosoma inside the body of
infected human
Cercariae
penetrates
human skin
Schisto-
somula
Venous circulation
Systemic circulation
Liver
Portal circulation
Vesical plexus
S.haematobium
I III
IV
II
Inf. mesenteric plexus
S.mansoni
Direction of venous blood flow
Aorta

9. Pathogenesis and Clinical Picture
There are 4 progressive stages:
Local dermatitis, irritation.
Papular rash.
I- Stage of invasion

10. II- Stage of migration
Metabolic products: toxic and allergic manifestations as
urticaria, fever, headache, muscle pain.
Eosinophilia, leucocytosis.
In the lung: verminous pneumonitis, minute haemorrhage,
cough, haemoptysis.
In the liver: enlarged and tender.
By schistosomula

11. III- Stage of egg deposition and extrusion
The patient may complain of:
Generalized malaise, fever,
rigors, urticaria, abdominal pain
and liver tenderness.
A- Eggs are deposited in the venous plexus

12. Katayama Syndrome
Blood vessel
Soluble egg antigens are
released in blood stream
Occurs mainly in S.japonicum
infection
1- ♀ lays large number of eggs
2- greater proximity to the liver
immune complex
Deposited in the tissues
Tissue damageThe patient suffers from:
Fever, chills, diarrhoea, generalized lymphadenopathy
Eosinophilia
Due to:
Thus also called acute toxoemic schistosomiasis
Circulate in blood

13. IV- Stage of egg deposition and extrusion:
Terminal haematuria
frequency of micturition
burning pain
Dysentery
(blood and
mucus in stool)
Vesical & pelvic plexus of veins
Bladder wall
mesenteric plexus of veins
Intestinal wall
This produces tissue damage & haemorrhage
In S.haematobium In S.mansoni & japonicum
B- Eggs escape from the veins to the perivascular tissue

14. IV- Stage of tissue reaction (chronic stage)
around Schistosoma eggs
trapped in various tissues.
Attract inflammatory cells
Deposition of fibrous tissue
Damage of affected organ
and its fibrosis
Loss of its function
Egg shell
miracidium
Inflammatory cells
Shell & miracidial antigens
Delayed-type hypersensitivity
e.g.Granuloma formation in
bladder
Where?
Granuloma develops

15. Polyps in the colon Barium enema that
shows polyps in the colon
Tissue fibrosis, nodules, papillomata & sandy
patches

16. IV- Stage of tissue reaction (chronic stage)
Liver: portal hypertension, hepatosplenomegaly,
oesophageal varices, ascites.
Lung: pulmonary hypertension, bilharzial cor-pulmonale.
Eggs swept
by blood
Eggs trapped in
Bladder wall
Eggs trapped in
Intestinal wall
Eggs that fail to fix to venule wall
cause Embolic lesions
Eggs swept
by blood
Eggs extruded in urine Eggs extruded in stool

17. Diagnosis
• Direct parasitological methods:
Detection of S.haematobium eggs in urine.
Test for viability.
Detection of S.mansoni eggs in stool by direct
smear method or by concentration method.
Kato thick faecal smear: for egg counting to
assess the intensity of infection
Rectal swab
• Blood examination:
eosinophilia, leucocytosis, anaemia.
I- Laboratory

18. Serological Tests:
1- IHAT (Indirect Haemagglutination test)
Detection of anti-Schistosoma antibodies or
antigen in patient’s serum
2- ELISA (Enzyme-linked immunosorbent assay)
3- IFAT (Indirect Fluorescent Antibody test)
wash wash
wash wash wash
Ab
detected
wash wash wash Ag
detected
Coating with
Schisto Ag
Coating with
anti-Schisto
monoclonal Ab
Latex particles
Sensitized sheep RBCs
+ve
-ve
Schisto Ag Patient
serum
Ab
detected

19. Calcified bladder
with hydroureter
Intestinal
affection
Stenosed ureters
and
hydronephrosis
II- Radiological imaging
S.haematobium infection S.mansoni infection

20. ‫المناظير‬III- Endoscopy
Cystoscopy
S.haematobium
Colonoscopy, sigmoidoscopy
S.mansoni
Done in chronic cases to detect lesions and take
biopsies

21. Treatment
Praziquantel
Prevention and Control
- Mass treatment.
- Health Education.
- Snail control:
Physical methods
Biological methods
Chemical methods
X
Balanites
aegyptica
Copper
sulphate

22. 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.

23. M.C.Q.
The major cause of morbidity in schistosomiasis is:
a- Migration of adult worms against blood stream.
b- Migration of adult worms in the liver.
c- Embolic lesions.
d- Deposition of eggs in tissues.
Kato technique is used to diagnose:
a- Paragonimiasis
c- Schistosomiasis haematobium
Bather’s itch occurs frequently with:
a- S.haematobium
b- S.japonicum
b- Schistosomiasis mansoni
d- Fascioliasis
b- S.mansoni
d- non human schistosomes

24. M.C.Q.
Katayama syndrome:
a- occurs most frequently in S.haematobium infection.
b- consists of pulmonary hypertension and right-sided
heart failure.
c- occurs most frequently in S.japonicum infection.
d- occurs in chronic schistosomiasis.

25. Give reasons for
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(.
Occurrence of terminal haematuria in S.haematobium
infection
Lumen of
urinary bladder

26. Give reasons for
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.
Occurrence of Bilharzial cor-pulmonale in
schistosomiasis
Swept
by blood
LungHeart