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MICR 454L

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MICR 454L

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  1. MICR 454L NOT FINAL YET Emerging and Re-Emerging Infectious Diseases Lecture 9: Cryptosporidium, Schistosoma Dr. Nancy McQueen & Dr. Edith Porter

  2. Cryptosporidium

  3. Cryptosporidium • Protozoa • Belongs to sporozoa • Reservoir • Mammals, birds, reptiles • Waterborne infection • Affects primarily intestinal tract Water Oocysts Sporozoites Sporozoites Invade intestinal epithelial cell

  4. Life Cycle of Cryptosporidium

  5. Cryptosporidiosis: Pathogenesis • Formation of a unique intracellular compartment in the apical region of the host cell • Involves rearrangement of the host cell cytoskeleton in intestinal epithelial cell • Incorporates host cell actin and alpha-actinin into a host-parasite junctional complex

  6. Cryptosporidiosis: Disease • Infectious dose ~ 10 oocysts • Autoinfection • Incubation time 2 – 10 days • Massive diarrheae • Up to 25 bowel movements • Millions of oocysts are shed • Up to 10 fluid loss • Accompanied by fever • Last about for 1-2 weeks • Life threatening for immunocomprised patients • Some may not develop symptoms

  7. Cryptosporidiosis: Diagnostic • Modified acid fast stain from stool sample (Kinyoun) • ELISA testing for Cryptosporidium antigen in stool samples • Molecular (PCR) 5 mm http://www.stanford.edu/class/humbio103/ParaSites2006/Cryptosporidiosis/Images/acid-fast%20crypto%20(2).jpg

  8. Cryptosporidiosis: Therapy • Nitazoxanide in otherwise healthy patients • Nitrothiazole benzamide • Blocks anaerobic metabolism • Inhibition of the ferredoxine reductase • Also used in worm infections, some anaerobic bacterial infections • Symptomatic • Improve immune system • Anti-retroviral therapy for AIDS patients

  9. Cryptosporidiosis: Prevention • Requires special water treatment in municipal systems • Routine chlorine does not inactivate oocysts • Small size allows penetration through routine filter • Home filtration • Reverse osmosis • 1 micron filters

  10. Threats by Cryptosporidium • 1993 Milwaukee outbreak • Contamination of the municipal water system • C. parvum • 100 deaths and 400,000 illnesses • Critical Biological Agent for Public Health Preparedness • Category B • Some potential for large-scale dissemination, but generally cause less-severe illness than those in Category A • Could be used to contaminate food or water sources, and many of them are relatively easy to obtain. • Difficult to detect, high dose in fecal movements and low infectious dose

  11. The worms crawls in, the worms crawl out, in your belly, and out your snout. ANONYMOUS

  12. Schistosoma Helminths Morphology Life cycles Vector Pathogenesis Diseases Diagnosis Therapy Prevention Threats Overview

  13. Phylum: Platyhelminthes (flatworms) Class: Cestodes (tapeworms) Class: Trematodes (flukes) E.g., Schistosoma Phylum: Nematodes (roundworms) E.g., Filaria Helminths: Classification • Animalia • Multicellular • Organs and biological systems* • Circulatory • Nervous • Reproductive • Hermaphrodites • Dioecious • Digestive • Excretory * Depending on species some systems may be lacking or rudimentary

  14. Trematodes • Flukes • Oral sucker: food uptake • Incomplete digestive tract • Ventral Sucker: Attachment • Mostly hermaphroditic (monoecious) Image 98601B

  15. Schistosoma • Schistosoma japonicum • Schistosoma mansoni • Schistosoma haematobium • Adult females • size 7 to 20 mm; males slightly smaller

  16. Schistosoma: Life Cycle (1) • Infection from contaminated fresh water in which certain types of snails that carry schistosomes are living • Schistosoma can penetrate the skin • Within several weeks, worms grow inside the blood vessels of the body and produce eggs. • Some of these eggs travel to the bladder or intestines and are passed in the urine or stool • Schistosoma eggs gain access to fresh water when infected people urinate or defecate in the water. Cercariae Sporocysts Human Adults Snail Miracidia Eggs

  17. Schistosoma: Life Cycle (2)

  18. Developmental Stages of Schistosoma Egg Miracidia Cercaria penetrating skin Adult male and female worms

  19. S. japonicum S. mansoni S. haematobium superior mesenteric veins of small intestine superior mesenteric veins draining of large intestine venous plexus of bladder Schistosoma and Affected Organs

  20. Schistosoma: Pathogenicity Factors • Soluble hypersensitivity antigen released by miracidia within the eggs. • Local inflammation • Tegument • Unique double membrane structure • Glycan rich surface • Antioxidant enzymes • Elastase-like IgE protease • Excretory/secretory (ES) molecules from cercariae down-regulate the host's immune response • Bind host defense molecules on their surface

  21. Schistosoma: Diseases • Bilharzia • Often asymptomatic • Acute schistosomiasis (Katayama's fever) • May occur weeks after the initial infection • S. mansoni and S. japonicum • Fever, cough, abdominal pain, diarrhea, hepatospenomegaly, and eosinophilia • Occasionally central nervous system lesions occur • granulomatous lesions around ectopic eggs • Brain, spinal cord • Chronic infection • Granulomatous reactions and fibrosis in the affected organs • Colonic polyposis with bloody diarrhea (Schistosoma mansoni mostly) • Portal hypertension with hematemesis and splenomegaly (S. mansoni, S. japonicum) • Cystitis and ureteritis (S. haematobium) with hematuria, which can progress to bladder cancer;

  22. Schistosoma and Cancer • General: • Chronic inflammation with chronic phagocytes at the inflammatory site • Release reactive oxygen radicals and reactive nitrogen radicals • Chronic inflammation leads to repeated cycles of cell damage and compensatory cell proliferation • Promoting neoplasia • Schistosoma specific • Adult schistosomes liberate carcinogenic amines in urine • Rised beta-glucuronidase levels originating from miracidia enclosed in the eggs Khurana S et al. (2005) Indian J Med Microbiol. 2005 Apr;23(2):74-9.

  23. Squamous Bladder Cancer Induced by Schistosoma Normal epithelium Squamous bladder cancer

  24. Schistosoma: Diagnosis • Microscopy • Antibody detection • ELISA and immunoblot • Schistosomal adult microsomal antigen • indicative only of schistosome infection at some time • cannot be correlated with clinical status, worm burden, egg production, or prognosis

  25. Schistosoma: Identification of Eggs Spine S. mansoni S. japonicum S. haematobium In Feces In Urine

  26. Schistosoma: Therapy • Praziquantel for all species

  27. Schistosoma: Prevention • No vaccine • No drug • Avoid wading, swimming or other fresh-water contact in endemic countries • Avoid untreated piped water coming directly from canals, lakes, rivers, streams or springs that may contain cercariae • Heating bathing water to 50°C (122°F) for 5 minutes or filtering water with fine-mesh filters • Allow bathing water to stand for 2 days because cercariae rarely remain infective longer than 24 h

  28. Schistosoma: Epidemiology • 200 million people infected world wide • 50% endemic among the local population in high infested areas • South America • Caribbean • Africa • Middle East • Far East Depends on species

  29. Schistosoma: Endemic Areas

  30. Threats by Schistosoma • Mainly threat to population in endemic areas and to travelers

  31. Resources • The Microbial Challenge, by Krasner, ASM Press, Washington DC, 2002. • Brock Biology of Microorganisms, by Madigan and Martinko, Pearson Prentice Hall, Upper Saddle River, NJ, 11th ed, 2006. • Microbiology: An Introduction, by Tortora, Funke and Case; Pearson Prentice Hall; 9th ed, 2007. • www.asnom.org/.../nodule_oncho.jpg • http://www.icp.ucl.ac.be/~opperd/parasites/images/man.jpg • http://www.the-travel-doctor.com/filari9.gif • http://www.payer.de/entwicklung/entw2029.gif • http://emu.arsusda.gov/typesof/images/onchyo.jpg • http://www.denniskunkel.com/product_info.php?products_id=1089 • http://www.denniskunkel.com/product_info.php?products_id=592 • http://www.cdc.gov/ncidod/dpd/parasites/schistosomiasis/default.htm • http://www2.ncid.cdc.gov/travel/yb/utils/ybGet.asp?section=dis&obj=schisto.htm • http://education.vetmed.vt.edu/curriculum/VM8054/Labs/Lab4/IMAGES/SIMPL%20COLM%202%20GALL.JPG • http://www.pathguy.com/lectures/bladder_cis.jpg