Schistosoma

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Medical Parasitology:

Medical Parasitology Dr : Ahmed Abd El-Aziz Lecturer of Parasitology Faculty of Medicine * Al- Azhar University

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. Schistosoma haematobium in Africa, Middle East Schistosoma mansoni in Africa, Saudi Arabia, South America Schistosoma japonicum in Far East Schistosoma intercalatum in some foci in West & Central Africa Schistosoma mekongi in Mekong basin (South East Asia) Blood flukes

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. Separate sex ( Scistosomes are not hermaphrodite) Male is flat and curved ventrally to form a gynaecophoric canal and female is cylindrical . Genital pore behind ventral sucker More than 2 testes Intestinal caeca reunite Eggs have spines (not operculated ) No redial stage inside the snail Infective stage: Cercaria (not encysted metacercaria ). Mode of infection: skin penetration (not by ingestion). The difference from other trematodes

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. Definitive Host : Man Intermediate host : B. alexandrina for S. mansoni B. truncatus f or S. haematobium Habitat : Blood vessels Adult S . haematobium live in vesical & pelvic plexus of veins. A dult S. mansoni live in i nferior mesenteric plexus of veins. Adult S . japonicum live in s uperior & inferior mesenteric plexus of veins

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. Diagnostic stage: S.Haematobium egg in urine S.Mansoni egg in stool Infective stage: Furco-cercous cercaria 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.

Pathogenesis:

Pathogenesis

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. There are 3 stages: I- Stage of invasion and migration : ( 3-4 weeks) by cercaria & schistosomula (from penetration of cercariae till egg deposition) Systemic : Metabolic products: toxic and allergic manifestations as urticaria , fever, headache, muscle pain. In skin : Local dermatitis and p apular rash In the lung :verminous pneumonitis ( cough , haemoptysis ) In the liver : enlarged and tender . Pathogenesis and Clinical Picture

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. II- Stage of egg deposition and extrusion (acute s tage : 1-2 month) A- Generalized malaise, fever, r igors , urticaria , abdominal pain and liver tenderness . Katayama Syndrome Soluble egg antigens immune complex Deposit in the tissues Tissue damage. Occurs mainly in S.japonicum infection due to: 1- large number of eggs 2- greater proximity to the liver C / P: Fever , chills , diarrhoea , GLN

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. B- Stage of egg extrusion: Eggs escape from the veins to the perivascular tissue due to: 1-Pressure within the venule 2-Effect of the spine 3-lytic secretion of the miracidium within the egg Damage & haemorrhage

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. S.haematobium In vesical & pelvic plexus of veins Egg extruded -Terminal haematuria . -Frequency of micturition. -Dysuria. S.mansoni & S.japonicum In mesenteric plexus of veins Egg extruded -Dysentery with blood and mucus in stool -Abdominal pain.

III- Stage of tissue reaction (chronic stage) (months- years). Eggs either trapped in wall or swept by blood (cause Embolic lesions) or extruded in urine or stool :

III- Stage of tissue reaction ( chronic stage) (months- years). Eggs either trapped in wall or swept by blood (cause Embolic lesions) or extruded in urine or stool Tissue reaction occurs around eggs deposited in various tissues (Delayed-type hypersensitivity Granuloma develops) Shell & miracidial antigens attract inflammatory cells Deposition of fibrous tissue Damage of affected organ and its fibrosis Loss of its function

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. In S.haematobium : In S.mansoni infection : Bladder fibrosis and calcification - Stone formation Hydroureter , hydronephrosis , renal failure - Cancer bladder - Fibrosis of the colon - Polyps , anemia - Hepatosplenomegaly , periportal fibrosis, portal hypertension, ascites , esophageal varices

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Embolic Lesions in the lung cor-pulmonale Bilharzial Pulmonary hypertension 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 CNS, skin, pericardium or any other organ.

PowerPoint Presentation:

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.

I- Laboratory Diagnosis:

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 shell Terminal spine Lateral spine S: C: Translucent C: Miracidium .

I- Laboratory Diagnosis:

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) (Immunodiagnostic Tests) Anaemia due to 1- Egg extrusion Iron deficiency anaemia 2- Hypersplenism Haemolytic anaemia . b- ELISA (Enzyme-linked immunosorbent assay ) c- IFAT (Indirect Fluorescent Antibody test ) d –COPT( circum oval precipitin test)

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II- Radiological imaging: X-ray , ultrasonography S.haematobium infection - Calcified bladder with hydroureter - Stenosed ureters and hydronephrosis S.mansoni infection - Intestinal affection(stricture)

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

Treatment :

Treatment Metrifonate ( bilarcil ) :10 mg/kg every 15 days for three doses Oxamniquine ( vansil ): 20 mg/kg for 3 days Praziquantel : 40 mg/Kg simgle dose Commiphora molmol ( mirazid ):300 mg x 2 x 6

Prevention and control:

Prevention and control Sanitary disposal system Protection from cercarial infection Wearing boots and gloves Drying of wet part after swimming in canalas Health education Mass treatment

Prevention and control:

Prevention and control Snail eradication Physical Clearing of weeds Double canal system Lining banks with concrete Using palm leafs to collect snails Covering of canals Biological Natural enemy as ducks Toxic plants as Balanitis aegyptica Chemical Copper sulphate 10-20 parts /million Baylucide 2 parts / million

Cercarial dermatitis Bather’s itch Swimmer’s itch:

Cercarial dermatitis Bather’s itch Swimmer’s itch Penetration of skin by cercariae of non human Schistosoma , mainly of birds Cause itching and dermatitis Treated by anti-allergic drugs and antibiotics if secondary infection

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