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Schistosoma Infection: Modes of Transmission, Clinical Features & Pathology

This text provides information on the various modes of transmission, clinical features, and pathology of Schistosoma infection, including its impact on different organs and systems within the body.

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Schistosoma Infection: Modes of Transmission, Clinical Features & Pathology

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  1. بسم الله الرحمن الرحيم TREMATODES

  2. Remember Autoinfection Mode of infection Infective stage Definitive host Intermediate host Type of parasites Source of infection Vector transmission

  3. SCHITOSOMA

  4. Diagnostic stage Egg with lateral spine Infective stage Forked tail cercaria

  5. Biomephlaria intermeddiat host

  6. Schistosoma mansoni Is caused by persons passing faces containing eggs of parasite into water which is used for bathing ,washing clothes ,fishing …. After mating ,mature S. mansoni flukes migrate to small tributary veins of inferior mesenteric, Which drain large intestine. flukes can also be found in portal venous system.

  7. Life cycle • Person become infected by contact with water containing infective cercaria . Cercaria attached to skin and are able to penetrate unbroken skin (can penetrate mucous membranes). • During penetration cercaria loss their tail and develop into schistosomules which migrate through SC tissue into blood vessels.

  8. In blood young flukes are carried through right side of heart to lung • From lung most of schistosomules pass through left side of heart ,enter abdominal aorta, and from there reach the portal (liver ) circulation. • In blood vessels of the liver ,young flukes reach maturity.

  9. . CLINICAL FEATURES : • Swimmer's itch: may occur at site of cercarial penetration. • In Schistosomiasis it is the eggs not adult which responsible for pathology. • Eggs acquiring host antigens and protected from attack by host immune responses. • Most eggs penetrate intestinal wall and excreted in stool with blood and mucus

  10. Trapped egg mature normally secreting antigens that produce strong immune response. Egg it self do not damage body, cellular infiltration resultant from immune response that cause pathology associated with schistosomiasis

  11. Eggs lodged in mucosa lead to formation of granuloma- ulceration and thickening of bowel • large granuloma lead to colonic and rectal polyp. • Eggs reach liver through portal vein causing thickening of portal vessels =periportal fibrosis –in heavy infection lead to enlarged liver with fibrosis-portal hypertension –ascites and splenomegaly. • Varicose v. in oesophagus –hematemesis • Eggs in spinal cord ,lung …..

  12. pathology & clinical picture of Schistosoma mansoni 1-per patent period. 2-egg deposition and extrusion. 3-tissue proliferation.

  13. 1-prepatent period: a-skin penetration: causing skin irritation N.B. from cercarial skin penetration to passage of eggs (adult stage) it take 5-7 weeks. b- systemic symptoms (slight fever, muscle pain,--)

  14. 2-Egg deposition and extrusion: • Affect mainly large intestinal wall, • liver and spleen. • Intestinal wall: schistosomal dysentery (blood and mucus exudates in stool) ,thickening and fibrosis of colon and rectum. • Hepatomegaly: due to egg deposition. • Splenomegaly: due to congestion • Egg deposition: in other organs e.g. kidneys and spinal cord.

  15. 3-Tissue proliferation & repair: Intestine: fibrosis, thickening and development of papillomata, loss of tone , fibrous constriction diarrhea fistulae.  Periportal fibrosis ,esophageal varices haematemesis ,ascitis.  Pulmonary complications: bronchopulmonary and cardiopulmonary (obstructive vascular disease ) cor pulmonale.  CNS involvement.

  16. Schistosoma hematobium Schistosoma hematobium

  17. Pathology: • Swimmer's itch • Hematouria–eggs penetrate wall of bladder (blood in urine). • Eggs trapped in wall of bladder causing granuloma. • Many eggs calcified (sandy patch) • Urinary infection–kidney damage – squamous cell carcinoma. • Stones , nephrotic syndrome.

  18. pathology& clinical picture of Schistosoma hematobium 1. Pre-patent period. 2. egg deposition and extrusion. 3. tissue proliferation.

  19. 1-Prepatent period a.Skin penetrations : cause skin irritation N.B. From cercarial penetration to passage of eggs (adult stage) it take 10- 12 weeks. b.Systemic symptoms (slight fever, muscle pain…)

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