Damage the parasite polymeizeshemeinto crystals to

This preview shows page 35 - 37 out of 40 pages.

damage. The parasite polymeizeshemeintocrystals to protect against oxidative damage.There are over 50 variants of thePfEMP1 protein and the parasitecan antigen switch to evadeimmune detection. However, onlyone (which binds chondroitinsulfate A) enables placentaladherence.
Intestinal ProtozoaGiardiaEntamoebaCryptosporidiumTransmissionFecal/oral:most commonly with water and MSMFecal/oral: most commonly in food and MSMFecal/Oral: most commonly waterand MSMDiagnosisMicroscopicexam of stool for cystsELISAHistology is normal because giardiais non-invasiveMicrscopicexam of stool for cystsBiospy: parasitesare found at the edges of visibledamageMicrscopicexam for oocystin fecesELISAfor antigenPCR not yet fully developedEpidemiologyMore common in developing countriesMost common cause of waterborne diarrhea outbreaks intheUS10% of the world infected, only minority developsymptoms3rdcause of death from parasitic diseaseHigherrisk in developing countriesOriginally zoonotic(sheep, cattle)ClinicalPresentationAsymptomaticin 40-60% of infectedSymptoms: abdominal pain, cramping, bloating, diarrhea,flatulence, malodorous stool, weight lossCan be asymptomaticAcute amebic colitis :diarrhea, dysentery, abdominalpain, low back pain, fever, abdominal tendernessSymptoms:waterydiarrhea, anorexia, weight lossSelf-limited in immunocompetenthostsCommon Features of Protozoan Parasites•Reproduce asexually within the human host such thatthe severity of disease does not depend on theinfecting dose•Cyst form has a resistant wall and is the infective form•Cysts transform to trophozoites, metabolically activeand motile forms of the protozoaSecretoryDiarrheaMalabsorptiveDiarrheaMechanismIncreasedCl-secretionby small intestinalcrypt cellsDamage to the brushborder epithelial cellsCausesToxinsInflammatorymediatorsAnything thatdamages the brushborderflatulence, malodorous stool, weight lossCauses malabsorptionsyndromes: steatorrhea,disaccharidasedeficiency (lactase deficiency can persistafterwards), D-xylose/B12/Folatemalabsorption, protein-losing enteropathy, vitamin A deficiencyMalabsorptionis likely due to mucosal damagepain, low back pain, fever, abdominal tendernessFulminantcolitisAmebomaExtraintestinalsite of amoebiasis:liver abscess (tenderliver, fever, hepatomegaly, diarrhea, weight loss)PathogenesisNOTCLEAR!Non-invasiveNo known toxin or conventional virulence factorCauses tissue damage by invading through IECsConsumes RBCsInduces formation of paristophorousvacuoleHost DefenseB lymphocytes (hypogammaglobulinemiacauses increasedincidence and severity of infections,but IgAdeficiency has noeffect)T lymphocytes: probelmaticgiardiainfections in AIDSDisease is worse in HIV patientsLife CycleEgg shaped cyst (4 nuclei) is responsiblefor transmissionOnce ingested, high body temperature and low gastric pHawakens the parasite. Excystationoccurs in the small intestineTrophozoite(2 nuclei, 4 pairs of flagella, helical motion)

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 40 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Spring
Professor
staff
Tags
Bacteria, Escherichia coli, gram negative bacteria, GI Tract, Gram positive bacteria

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture