Schistosoma Parasites Adult Flukes live in blood vessels of infected Humans...
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Transcript of Schistosoma Parasites Adult Flukes live in blood vessels of infected Humans...
Schistosoma Parasites
Adult Flukes live in blood vessels of infected Humans
S.haematobium S.mansoni S.japonicum
Called Blood Flukes
D.H: ManR.H: Rodent, Monkeys
D.H: ManR.H: Domestic animals
D.H: ManR.H: None
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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
Inferior mesenteric plexus of
veinsWhere adult
S.japonicum liveRAAFAT T. MOHAMED
• 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.
Schistosoma differs from other trematodes in:
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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 (1915- 1918): Discovered the relation to snail intermediate hosts and the mode of infection.
McDonagh (1918)Used tartar emetic for treatment
Recent discovery:
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Sexes: separateFemale: cylindricalMale: flattened, folded (gynaecophoric canal).
Suckers: oral & ventral (smaller in females).
Digestive system :
No muscular Pharynx Intestinal ceaca reunite in a single caecum.
Adult Morphology
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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
Male
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FemaleS. haematobium 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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EggS. haematobium
S. mansoni S. japonicum
In urine In stool
Size 140x 60 150x60 85x65
Shape Ovalterminal spine
OvalLateral spine
OvoidMinute knob
Shell translucent, non operculated
Content Mature embryo (miracidium)
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Miracidium
S. mansoni
Biomphalaria alexandrina
Snail I. H
S. Haematobium
Bulinus truncatus
S. japonicum
Oncomelania
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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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Worms in their habitat
Female lays eggs
Eggs in urine or stools
Miracidia hatch
Miracidium infects snail i.h.
Cercarial shedding
Infection in contaminated
water
Schistosomulum reaches circulation
Worms mate in the liver
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Life cycle
S.mansoni live worm pair.mp4
Schistosoma Mansoni Miracidium inside the Egg.flv
Schistosoma Mansoni Penetrating Human Flesh!.mp4
WTDV027421.swf
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Development of Schistosoma inside the body of infected human
Cercariae penetrates human skin
Schistosomula
Venous circulationSystemic circulation
Liver
Portal vein
Vesical plexus
IIII
IV
II
Inf. mesenteric plexus
Aorta
♂♀
In urine or stoolDirection of venous blood flow
S.haematobium
S.mansoni
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Pathogenesis and Clinical Picture
There are 4 progressive stages:
I- Stage of invasion
Local dermatitis, irritation.
Papular rash.
(1-4 days)
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II- Stage of migration
By schistosomula
(3-4 weeks)
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.RAAFAT T. MOHAMED
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
Urticaria
(acute stage: 1-2 month)
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Katayama Syndrome
Blood vessel
Soluble egg antigens are released in blood stream
Occurs mainly in S.japonicum infection
1- ♀lays large number of eggs2- greater proximity to the liver
immune complex
Deposited in the tissues
Tissue damageThe patient suffers from:
Fever, chills, diarrhoea, generalized lymphadenopathy
Due to:
Thus also called acute toxoemic schistosomiasis
antibodies
Circulate
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B- Stage of egg extrusion:
Terminal haematuria, frequency of micturition, burning pain
Dysentery with blood and mucus in stool
In vesical & pelvic plexus of veins
Bladder wall
In mesenteric plexus of veins
Intestinal wall
Damage & haemorrhage
S.haematobium S.mansoni & S.japonicum
Eggs escape from the veins to the perivascular tissue due to:
1-Pressure within the venule2-Effect of the spine3-oozing lytic secretion of the miracidium within the egg
Egg extruded Egg extruded
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IV- Stage of tissue reaction (chronic stage)
Occurs around Schistosoma eggs deposited in various tissues.
Attract inflammatory cells
Deposition of fibrous tissue
Damage of affected organ and its fibrosis
Loss of its function
Egg shellmiracidium
Inflammatory cells
Shell & miracidial antigens
Delayed-type hypersensitivity
Granuloma formation in tissue
(months – years)
Granuloma develops
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Polyps in the colon in S.mansoni infection
hydroureter
hydronephrosis
Egg trapped in bladder wall
Fibrous tissue
Stone formation
In normal condition
In S.haematobium infection
Cancer bladder may occur
Normal mucosa of colon
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IV- Stage of tissue reaction (chronic stage)
In S.haematobium infection In S.mansoni infection
Eggs extruded in urine1
Eggs trapped in Bladder wall
2
Eggs fail to fix to venule wall are swept by
blood
3
Eggs trapped in Intestinal wall
Eggs extruded in stool
1
2
Eggs fail to fix to venule wall are swept by
blood
3
Cause Embolic lesions Cause Embolic lesions
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Embolic Lesions in the LiverPortal hypertension Hepatosplenomegaly
Oesophageal varicesAscites.
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Embolic Lesions in the lungPulmonary hypertensionBilharzial cor-pulmonale
Embolic lesions may occur in any other organ.
Cor-pulmonale = right-sided heart failure
Dilated right ventricle
Thickened wall
In Normal condition
In Schistosoma infection
Enlarged right ventricle
Trapped eggs
Means: enlargement of right ventricle due to high blood pressure in the arteries of the lung
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Diagnosis of Schistosomiasis
Clinically (suggestive)
Laboratory
1- Detection of eggs in urine or stool
3- Serological tests
2- Blood examination
Radiological imaging
Endoscopy
1- History of contact with infected water.2- Clinical picture according to stage of infection.
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I- Laboratory Diagnosis
1- 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
S: 140X60 µ 150X60 µ
Oval, thin shellTerminal spine Lateral spineS:
C: Translucent C: Miracidium
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I- Laboratory Diagnosis
Eosinophilia, leucocytosis.
2- Blood examination:
3- Serological Tests:Detection of anti-Schistosoma antibodies or antigen in patient’s serum
a- IHAT (Indirect Haemagglutination test)
Latex particles
Sensitized sheep RBCs
+ve
-ve
(Immunodiagnostic Tests)
Anaemia due to
1- Egg extrusionIron deficiency anaemia
2- Hypersplenism Haemolytic anaemia
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b- ELISA (Enzyme-linked immunosorbent assay)
c- IFAT (Indirect Fluorescent Antibody test)
wash wash
wash wash washAb
detected
wash wash wash Ag detected
Coating with Schisto Ag
Coating with anti-Schisto
MAb
Schisto AgPatient serum
Ab detected
Patient’s serum
Ab linked to enzyme substrate
substratePatient’s serum
Ab linked to enzyme
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Calcified bladder with hydroureter
Intestinal affection
Stenosed ureters and
hydronephrosis
II- Radiological imaging
S.haematobium infection S.mansoni infection
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III- Endoscopyالمناظير
Cystoscopy in S.haematobium
Colonoscopy, sigmoidoscopy in S.mansoni
Done in chronic cases to detect lesions and take biopsies
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Treatment
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Praziquantel (Biltricide): For all schistosome species.Dose:40 mg/kg single oral dose
Oxamniquine (vancil):For S. mansoniDose: 30 mg/kg for 2 days
Metriphonate:For S. haematobium only. Dose: 10mg/kg every 2 weeks for 3
doses.
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Prevention and Control
- Mass treatment.
- Health Education.
- Snail control:
Physical methods
Biological methods
Chemical methods
X
Balanites aegyptica
Copper sulphate
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.RAAFAT T. MOHAMED
b- S.japonicum
b- Schistosomiasis mansoni
d- Fascioliasis
b- S.mansonid- non human schistosomes
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
c- Schistosomiasis haematobium
Bather’s itch occurs frequently with:a- S.haematobium
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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.
Multiple Choice Questions
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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
Egg passes lumen of urinary
bladderRAAFAT T. MOHAMED
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
Lung Heart RAAFAT T. MOHAMED