parasitology Lecture 2
Terms
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- Apicoplast
- Derived from chloroplast, 2 phagocytic events, no longer photosynthetic
- Apicomplexa types
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1.Plasmodium-1=mosquito, 2=humans
2.babesia-1=tick, 2=mammals
3.toxoplasma gondii-1=cat, 2=mammals
4.cryptosporidium-1=mammals, 2=mammals
5.cyclospora-1=mammals, 2=mammals - Apicomplexa Life cycle names (asexual)
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1.merozoite(ring)
2.trophozoite
3.schizont - Apicomplexa Life cycle names (sexual)
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1.Gametes
2.Oocyst
3.Sporozoite - Malaria Epidemiology
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Developing world-300mill cases, 2mill deaths, 90% in Africa
US-1000 cases - Malaria Vector
- Vector(=1o host) =female mosquitoes(anopheles), bite-night(1am)
- Malaria Human life stages
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1.pre-erythrocytic stages(asexual types)
2.erythrocytic asexual stages(asexual types)
3.erythrocytic sexual stages(gametocytes)
4.hypnozoite - Malaria clinical course
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Prepatent period-asymptomatic, multiplying in liver
Paroxysm-shaking chills, then ↑fever(to 106) when RBC burst to release new merozoites, periodic(48-72hrs) - Malaria diagnosis
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1.Giemsa-stained blood smears(thick/thin)
2.Rapid tests
3.Travel history-beware of autochthonous(gotten here) - Plasmodium Vivax/ovale
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1.invade reticulocytes, live in enlarged RBC(schuffner’s dots)
2.produce latent form(hypnozoites)-dormant in liver(months-years then re-initiate parasitemia
3.48hr periodicity - Plasmodium Malariae
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1.NO hypnozoites-persist in blood at low levels
2.72hr periodicity - Plasmodium Falciparum
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1.invade RBC of all ages
2.Sickle-shaped gametocyte(unique)
3.48hr periodicity - Why is falciparum malaria the most leathal?
- Mature P. Facliparum secrete prots into RBC->form Knobs on RBC surface, Knobs cytoadhere to caps and are sequestered->block flow to brain
- Transmition differences in diseases
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⬢High Transmition->adults immune, disease in kids/primigravidae
⬢Low Transmition->all ages/gravidity - Genetics/resistance to malaria
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1.sickle cell trait
2.thalassemia
3.gluc-6-phosph dehydrogenase deficiency
4.ovalocytosis
5.duffy blood group negative - Babesiosis (location, vector, reservoir)
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1.Intra-erythrocytic parasite(like malaria
2.Tick-borne(ixodes scapularis)
3.Reservoir=white-footed mouse - Toxoplasma Gondii Survives How?
- Survives in Macs-in phagosome by preventing fusion w/ lysosome
- Toxoplasmosis definitive hosts
- Only Cats, schizogony+sexual repro in Gut
- Toxoplasma Gondii Intermediate Hosts
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1.Humans + 200 other mammals
2.Macs, Fibroblasts, Intestinal epithelium
3.Bradyzoites(cysts)
4.Tachyzoites(trophozoites) - Toxoplasmosis Epidemiology
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Seroprevalence in US=22%
Seroprev. In developing/france is higher (50%) - Toxoplasmosis Routes of infection
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1.Oocyst from cat feces
2.Cyst (bradyzoites) from undercooked meat(steak tartar) - Toxoplasmosis Acute disease
- 10-20% develop mono like illness
- Congenital Toxoplasmosis
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1.Primary infection during:
⬢1st trimester->congenital malformations(hydrocephalus, retardation), ocular disease
⬢2nd/3rd trimester->abortions
2.Non-immune women should avoid cats/raw meat - AIDS w/ Toxoplasmosis
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AIDS Reactivates Latent infection
1.Encephalitis=usually fatal
2.Retinal lesions
3-5% of all opportunistic infections
Protect w/ cotrimoxazole(TMP/SMX) prophylaxis - Toxoplasmosis Diagnosis
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1.Serology
2.Culture/inoculation of mice - Toxoplasmosis Treatment
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1.Antifolates (pyrimethamine/sulfadiazine)
2.Atovaquone - Cryptosporidium parvum/hominis/etc. Characteristics
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1.Cattle pathogen
2.humans in 1976
3.water-bourne in 1985
4.opportunistic w/ AIDS
5.NO Effective Treatment
6.Immunocompetent=mild diarrhea
7.Immunocompromised=severe diarrhea - Cryptosporidiosis Transmition paths
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1.Drinking water
2.swimming pools
3.food - Cryptosporidiosis survival characteristic
- Cysts are chlorine-resistant
- Cryptosporidiosis Outbreaks
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>100 in US
Day-care
Municipal water supplies
Big Milwaukee outbreak(400,000 cases) - Cryptosporidiosis Epidemiology in immunocompetent
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⬢Developing countries-6% of diarrhea
⬢Developed count.-2% of diarrhea - Cryptosporidiosis Epidemiology in HIV
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⬢Developing-24% of diarrhea
⬢Developed-14% of diarrhea - Cryptosporidiosis Prevalence
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Prevalence based on serology in adults
⬢brazil-100%
⬢china-60%
⬢US-20% - Cryptosporidiosis Genotypes
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1.Cryptosporidium Hominis=humans only
2.Cryptosporidium Parvum=Cattle and humans - Cryptosporidiosis Genotypes in US/UK
- C. hominis
- Cryptosporidiosis genotypes in developing countries
- Usually C. parvum
- Cyclospora sp. characteristics
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1.Looks like Cryptosporidium but bigger
2.same life cycle as Cryptosporidium
3.NO ANIMAL RESERVOIR - Cyclosporiasis characteristics
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1.Looks like cryptosporidium but bigger
2.Causes illness like cryptosporidium
3.2-20% prevalence in developing count. - Cyclosporiasis outbreaks
- In N. America due to imported Guatemalan raspberries
- Cyclosporiasis treatment
- bactrim