Protozoa Flashcards by Saloni Malik

What three protozoa cause GI infection?

Giardia lamblia
E. histolytica
Cryptosporidium

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What is the presentation of Giardia?

Bloating, flatulence, foul-smelling fatty diarrhea, often seen in campers/hikers

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What is the transmission of Giardia?

Cysts in water - fecal oral

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What is the Dx of giardia?

flagellated trophozoites or cysts in stool.

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What does Giardia trophozoite look like?

Like an alien head.

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What is the treatment for giardia?

metronidazole

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What is the transmission of e. histolytica?

fecal oral - cysts in water

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What is the presentation of E. histolytica?

Blood diarrhea (trophozoites invade the mucosa)
Liver abscess w/ anchovy paste exudate
RUQ pain, flask shaped ulcer
90% of ppl with e. histolytica are asx

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What does E. histolytica look like histologically?

Trophozoites have RBCs in the cytoplasm

Cysts have up to 4 nuclei (bulls eye shaped)

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What is the treatment for E. histolytica?

Metronidazole

Iodoquinol for asx cyst passers

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What is the transmission of cryptosporidium?

Oocytes (the infective agent, contains 4 sporozoites) in water, fecal oral.

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What does cryptosporidium look like histologically?

oocytes on acid-fast stain.

Obligate intracelluar, life cycle occurs w/in epithelial cells.

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What is the disease presentation of cryptosporidum?

immunocompetant: mild watery diarrhea

2. AIDS: severe diarrhea

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What is the treatment for cryptosporidium?

Prevention (filtering water supply)

2. Nitazoxanide

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What three protozoa cause CNS disease?

Toxoplasma
Naegleria fowleri
Trypanosoma brucei

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What are the routes of transmission for toxoplasma?

Ingestion of cysts in meat (esp raw pork)
Inhalation of oocysts in cat feces
* crosses placenta!*

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What is the presentation of congenital toxoplasmosis?

Chorioretinitis, hydrocephalus, and intracranial calcifications

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What is the presentation of toxoplasmosis in immunocompromised (AIDS) pts?

Brain abscesses seen as ring-enhancing lesions on CT/MRI. Can progress to disseminated infxn involving chorioretinits, liver/spleen/lungs etc.

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What does toxoplasma gondii look like histologically?

serology/bx shows tachyzoite: crescent shaped thingy.

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What is the treatment for toxoplasma?

sulfadiazine and pyrimethamine

+ folinic acid, decreases risk of bone marrow depression

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What is the source of transmission of N. fowleri?

Swimming in freshwater lakes, enters via cribiform plate

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What is the presentation of N. fowleri?

rapidly fatal meningoencephalitis.

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What is the histological finding of. N fowleri?

amoebas in CSF

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What is the treatment for N. fowleri

Almost always fatal, amphotericin B has worked in the few survivors.

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What is the transmission of trypanosoma brucei?

Tsetse fly, a painful bite

What are the subspecies of trypanosoma bruceii?

Trypanosoma brucei rhodesiense, gambiense

What is the disease caused by T. bruceii?

African sleeping sickness 1. hard, red painful ulcer at site of tseste fly bite, heals in 2 weeks 2. enlarged lymph nodes, recurring fever (due to antigenic variation - of surface glycoprotein VSG, progeny elude from a while) 3. CNS sx: somnolence, coma

What does t. bruceii look like histologically?

Blood smear shows flagellated organisms (trypomastigotes)

What is the treatment for t. bruceii?

1. Suramin for blood borne disease | 2. Melarsoprol for CNS penetration

What protozoa cause hematologic infections?

Plasmodium, babesia

What are the sub-species of plasmodium?

Falciparum Vivax/ovale Malariae

What is the mode of transmission for plasmodium species?

Anopheles mosquito bite.

What is the life span of plasmodium species?

Exo-erythrocytic cycle: 1. Sporozoite enters blood stream, travels to liver 2. Invades hepatocyte, rounds up to form a ball, becomes a trophozoite 3. Trophozoite undergoes nuclear division, thousands of nuclei: Schizont 4. Membrane forms around each nucleus, thousands of small bodies called merozoites 5. Liver cell bursts, merozoites enter bloodsteam -- Erythrocytic cycle: 1. Enters RBC, rounds up to form trophozoite: looks like diamond ring 2. Nuclear division --> schizont --> membranes form --> merozoites--> 3. Red cell lysis stimulates immune response.

What is unique about p. vivax/ovale lifespan?

Can lie dormant in the hepatocytes as hypnozoites, manifest disease years later

What sx do all malaria infections share?

Cycling fevers, headache, anemia, splenomegaly.

What interval of fevers occur with p. vivax/ovale?

Fevers 48 hrs apart (tertian)

What interval of fevers occur with p. malariae?

Fevers 72 hrs apart (quartan)

What interval of fevers occur w/ p. faliciparum?

Severe, irregular patterns, can be continuous.

What are the severe disease manifestations of malaria and which one causes it?

P. falci. Parasitized RBCs occlude capillaries in brain, kidneys, lungs.

What does plasmodium look like histologically?

1. Trophozoite ring form w/in RBC 2. Schizont containing many merozoites 3. P. vivax/ovale: Schuffer stippling: red granules seen throughout RBC cytoplasm

What is the treatment for plasmodium?

Falci is chloroquine resistant: mefloquine, atovaquone, or proguanil. Sensitive species: chloroquine (blocks p. heme polymerase)

What is the treatment for life-threatening plasmodium?

IV quinidine or artesunate. Add primaquine for hypnozoite.

What condition should be tested for with malaria treatment?

G6PD deficiency (primaquine, artesunate).

What populations have resistance to P. falci?

Sickle cell trait is protective.

What populations have resistance to P. vivax?

Many African Americans lack red cell membrane Duffy a and Duffy b antigens that p vivax uses for binding.

How is babesia transmitted? Where is it endemic?

Bite of ixodes tick. Northeast MA.

What is the histological appearance of babesia?

Ring form or Maltese cross - tetrad of merozoites.

What is the presentation of babesiosus?

Fever and hemolytic anemia. Asplenia increases risk of severe disease.

Which protozoa are responsible for visceral infections?

Trypansoma cruzi and Leishmania donovani

What bug is associated with Chagas disease?

Trypanosoma cruzi

What is the mode of transmission of Chagas disease?

Reduviid bug (kissing bug), painless bite

What does trypanosoma look like histogically?

Extracellular: flagellated trypanomastigote Intracellular: in macs, lymph nodes, organs --> non-motile

Where is Chagas disease endemic?

South America

What is the presentation of Chagas disease?

Dilated cardiomyopathy w/ apical atrophy | Megacolon, megaesophagus

What is the Romana sign?

Unliteral periorbital swelling characteristic of acute stage of Chagas disease

What is the treatment for Chagas disease?

Benznidazole or nifurtimox

What is kala-azar?

Visceral leishmaniasis

What is the transmission of Leishmania?

Sandfly

What does leishmania look like histologically?

macrophages containing amastigotes

What is the presentation of visceral leishmaniasis?

Spiking fevers, hepatosplenomegaly, pancytopenia.

How can non-visceral leishmaniasis present?

cutaneous - varying degrees depdning on species. Ulcer at the site, diffuse cutaneous, etc.

What is the treatment for diffuse cutaneous leishmaniasis?

Ampho B, sodium stibogluconate.

What is the mode of transmission of trichomonas vaginalis?

Sexually transmitted

How does trichomonas appear histologically?

Trophozites on wet mount - flagellated organism.

How does trichomonas present?

Vaginitis: foul-smelling, greenish discharge, itching and burning. Strawberry cervix.

What is the treatment for trichomonas?

metronidazole for patient and partner.

Protozoa Flashcards

(66 cards)