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42 Cards in this Set
- Front
- Back
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Endoparasites include?
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- Protozoa; single-celled
- Metazoa (helminths) |
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Types of Metazoa
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- Cestodes (segmented worms)
- Trematodes (flatworms) - Nematodes (roundworms) |
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Ectoparasites include?
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- Hexapoda (Lice)
- Arachnida (mites) |
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Human -> Human
Fecal-oral parasite spread |
- Amebiasis
- Ascariasis - Cryptosporidiosis - Giardiasis - Strongyloidiasis - Whipworm |
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Human -> Human
Fecal-cutaneous parasite spread |
- Hookworm
- Strongyloidiasis |
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Human -> Human
Vector-borne parasites |
- Leishmaniasis
- Lymphatic filariasis - Malaria - Onchocerciasis |
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Animal -> Human
Fecal-oral parasites |
- Cryptosporidiosis
- Echinococcosis - Toxoplasmosis - Visceral larva migrans |
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Animal -> Human
Fecal-cutaneous parasites |
- creeping eruption (dog/cat hookworm)
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Animal -> Human
Vector-borne parasites |
- Trypanosomiasis
- Leishmaniasis |
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Animal -> Human parasites spread by inadequate cooking
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- Beef tapeworm
- Fish tapeworm - Pork tapeworm - Toxoplasmosis |
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Type 1 immunity
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- IFN-γ production
- MΦ activation/CTL help - DTH responses |
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Type 2 Immunity
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- IL-4 production
- Ab responses - IgE/eosinophils |
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IFN-γ
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- Inhibits B cells
- Inhibits CD4+ TH2 cell - activates MΦ |
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Type 1 immune response to parasites
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- intracellular parasites activate type 1 immunity
- CD4+ T cells inhibit endosomal replication - CD8+ T cells target cytosolic replication |
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Type 2 immune response to parasitic infection
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- Antibody initiates complement/ADCC mechanisms
- Mast cells and eosinophils release toxic granules |
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Entamoeba histolytica
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- Human fecal-oral transmission
- Extracellular GI pathogen - Secretes potent proteases - RBC phagocytic ability - Lyses inflammatory cells - Secretory IgA provides possible protection |
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Giardia lamblia
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- Human fecal-oral transmission
- Fresh standing water reservoirs - Extracellular GI pathogen - Secretory IgA protective - "owl's eyes" apperance |
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Cryptosporidia parvum
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- Extracellular/"intracellular" GI pathogen
- Opportunistic infection/disease - Epidemics related to contaminated water - stains "acid-fast" |
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Trichomonas vaginalis
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- sexually transmitted protozoa
- Extracellular GU pathogen |
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Entamoeba histolytica lifecycle
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- Quadranucleate cysts ingested w/ fecally contaminated food or water
- Trophozoites develop in small intestine -- invade tissues of colon - Trophozoites encyst in colon - cysts pass with feces - |
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Pathology of Entamoeba histolytica
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- invades epithelium of colon, creating flask-shaped ulcers.
- liver abscesses - brain abcesses |
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Life cycle of Giardia lamblia
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- Quadranucleate cysts ingested with fecally contaminated water or food
- Trophozoites emerge in small intestine/ live on surface of villi - trophozoites encyst in small intestine - cysts pass with feces |
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Pathology of Giardia lamblia
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- Flattening of intestinal villi
- acute infection shows sudden onset with foul smelling, watery diarrhea |
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Life cycle of Cryptosporidium parvum
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- Sporulated oocyst ingested along with fecally contaminated water or food
- Sporozoites released from oocyst in small intestine - attach to surface of columnar epithelial cells - differenciate into two sexual stages - unsporulated oocyst passes in feces |
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Lifecycle of Trichomonas vaginalis
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- sexually transmitted
- Trophozoites live in prostate and urethra - similar to non pathogenic species which are normal flora |
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Life cycle of Plasmodium falciparum
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- Sporozoites injected during 2nd blood meal
- enter bloodstream, form cryptozoites - Exoerythrocytic cycle - infected liver cell ruputres to release merozoites - erythrocytic cycle begins - signet ring stage in peripheral blood - banana shaped gametocytes ingested during first blood meal |
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Plasmodium vivax lifecycle
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- infected bite injectes sporozoites
- enter bloodstream, begins exoerythrocytic cycle - merozoites rupture from infected liver cell - erythrocytic cycle begins - signet ring -> trophozoite -> visible schizont -> merezoites -> signet ring - round gametocytes ingested during blood meal |
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Differences between plasmodium falciparum and Plasmodium vivax
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- P. falciparum infects all peripheral RBCs (30% or more visible in smear is diagnostic)
- P. falciparum associated with drug resistance - P. falciparum infected RBCs microagglutinate - P falciparum smear with trophs/gametocytes only - P vivax persists in exoerythrocytic stage (in liver). |
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Malaria Vaccine Challenges
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- Distinct life stage antigens
- Antigenic variation between strains - Replicates in RBCs (no class I or II) - Th1/CTL attack infected hepatocytes only - Polyclonal gammopathy dilutes Ag-sp Ab. |
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Toxoplasma gondii lifecycle
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- pseudocysts ingested in undercooked meats
- oocysts in feces of cats/mice - Tachyzoites infect liver cells via bloodstream - Infected macrophages distribute tachyzoites throughout body - pseudocysts produced in response to acquired immunity |
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Pathology of Toxoplasma gondii
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- congenital infection
- chorioretinitis - hepatitis - lymphadenitis - brain lesions |
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Toxoplasma gondii biology
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- infected animal feces orally transmitted
- mostly intracellular infection - type 1 immunity protective - mainly opportunistic infection/disease - immunopathology in immunocompetent |
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Trypanosoma cruzi life cycle
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- kissing bug bites/defecates
- trypomastigote enters wound/mucous membrane - invade cells, transform into amastigotes - intracellular amastigotes live in tissues - extracellular trypomastigotes ingested druing blood meal |
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Pathology of African Trypanosomiasis
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- African sleeping sickness (T. brucei, gambiense, brucei rhodesiense
- transmitted by tsetse fly - primary legion or chancre - enters CNS to cause fatal lethargy |
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Pathology of American Trypanosomiasis
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- Central and S. America (T. cruzi)
- not transmitted by bite, rather from feces - Chagas disease |
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T. cruzi Biology/Immunity
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- Mucosal/cutaneous/parenteral infection
- Intracellular/extracellular life stages - infects any nucleated mammalian cell - escapes phagosome/cytoplasmic replication - Th1 & CTL critically important - Abs protect against extracellular stage |
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African Trypanosoma biology
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- transmitted by bite alone
- only extracellular life stages - targeted by lytic antibodies - VSG allows immune escape - increasing waves of parasitemia |
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Leishmania tropica life cycle
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- Sandfly bite injects parasites with meal
- intracellular amastigotes invade macrophages - cutaneous lesion forms - sandfly bites again, acquires amastigotes in WBCs. |
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Cutaneous leishmaniasis
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- Leishmania tropica
- N. & W. Africa, Iran, Iraq - ulcerating single or multiple skin sores, spontaneous healing with scar - L. mexicana in Mexico & Guatemala - Single lesion which heals rapidly |
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Mucocutaneous leishmaniasis
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- aka espundia
- L. viannia brasiliensis - Central & S. America, esp. Amazon - mucosal-dermal juncions of nose and mouth attacked, multiple lesions - death from secondary infection |
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Visceral leishmaniasis
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- L. donovani
- India, East Africa, China - infects macrophages, then migrates to spleen, liver, bone marrow - enlarged spleen/liver, jaundice - spontaneous resolution/death |
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Leishmania Immunity
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- Restricted macrophage trophism
- replicates endosomally - Th1 immunity protective - Tregs allow parasite persistence - Kala-azar assoc. with Th2 immunity - Vaccines can hasten ulcer healing |
