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The Biology of Schistosomiasis

The Biology of Schistosomiasis. By: Tricia Stone, Marielle Remillard & Tracy Wright. Schistosomes. macroscopic parasite from the genus Schistosoma characterized by significant sexual dimorphism Schistosoma= split body. Types of Schistosomes. Three species affect humans:

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The Biology of Schistosomiasis

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  1. The Biology of Schistosomiasis By: Tricia Stone, Marielle Remillard & Tracy Wright

  2. Schistosomes • macroscopic parasite from the genus Schistosoma • characterized by significant sexual dimorphism • Schistosoma=splitbody

  3. Types of Schistosomes • Three species affect humans: 1.) S. mansoni: large intestine 2.) S. japonicum: small intestine 3.) S. haematobium: urinary bladder

  4. Life Cycle intermediate fresh water snail host miracidia feces and urine

  5. Intermediate Snail Hosts • S. mansoni: Biomphalaria (Africa) • S. haematobium: Bulinus (Africa) • S. japonicum: Oncomelania (Asia) Biomphalaria Bulinus Oncomelania

  6. Life Cycle intermediate fresh water snail host cercariae

  7. YUMMY!! Life Cycle in the Human cercariae human host human host

  8. Life Cycle in the Human schistosomulum human host

  9. Life Cycle in the Human schistosomulum human host adult schistosome

  10. Life Cycle in the Human eggs excreted in the feces and urine adult schistosome

  11. Life Cycle

  12. Stage 1: Migratory Phase • moves through the body to target tissue • begins with penetration through egg production • often symptomless • possible rash and itchy skin • some upper respiratory complications (i.e. cough)

  13. Stage 2: Acute Phase • 4-10 weeks after infection • begins with egg production • Symptoms: - fever - headache - diarrhea - fatigue - nonspecific abdominal pain

  14. Stage 3: Chronic Phase • prolonged infection (up to 10 years) symptoms: - cirrhosis of the liver - kidney damage - bleeding of upper bowel - urinary bladder damage - enlargement of liver and spleen

  15. “Slippery Little Suckers Aren’t They…”~Julia Roberts (Pretty Woman) • Innate Immunity • penetration of skin • Specific Immunity • adults take on host antigens

  16. Incidence

  17. Risk Factors • 200 million infected globally • 20 million with chronic schistosomiasis • 600 million at risk -extreme poverty -lack of public health facilities -unsanitary conditions -unawareness among the people

  18. Prevention • avoid swimming in fresh water in countries where schistosomiasis is prevalent. • drink clean water • scrape body down after accidental exposure • water-resistant creams • Snail Control

  19. Diagnosis and Treatment • Diagnosis • blood tests • examination of stool and urine samples to detect eggs • Treatment • Drugs • Praziquantel - effective in the treatment of all forms of schistosomiasis, with virtually no side effects * • Oxamniquine - used exclusively to treat intestinal schistosomiasis in Africa and South America * • Metrifonate - effective for the treatment of urinary schistosomiasis • Vaccination • Research efforts are directed at finding a vaccine, but no success *obtained from W.H.O.

  20. Interested in More??? • http://www.wellcome.ac.uk/en/labnotes5/animation_popups/schisto.html • http://www.cdc.gov/ncidod/dpd/parasites/schistosomiasis/default.htm • http://en.wikipedia.org/wiki/Schistosomiasis • http://www-micro.msb.le.ac.uk/224/Schisto.html • http://www.path.cam.ac.uk/~schisto/

  21. Questions??????

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