Parasitology - Protozoa Flashcards
What are the 3 protozoan that infect the GI tract?
1) Giardia lamblia
2) Entamoaba histolytica
3) Cryptosporidium
What are the symptoms of Giardiasis?
Bloating, Flatulence, Foul-smelling + FATTY diarrhea
Who is Giardiasis seen in? What is it’s “street name”?
Campers/hikers; Beaver Fever
How is Giardia lamblia transmitted?
Cysts in water; animals (beavers) shit in the river, you drink the water down stream
How do you diagnose Giardia lamblia?
Trophozoits or cysts in stool
What is the treatment for Giardia lamblia?
Metronidazole
What are the symptoms of Amebiasis?
(Entamoaba histolytica) Amebiasis: BLOODY diarrhea (dysentery), liver abcess (w/ “anchovy paste” exudate), RUQ pain
What will histology show if a submucosal abscess of the colon ruptures in Amebiasis?
A flash-shaped ulcer
How is Entamoeba histolytica transmitted?
Cysts in water (active trophozoite found only in host and fresh feces; cysts live outside host in water, soil, and food - especially in moist conditions)
How do you diagnose Amebiasis?
Serology and/or trophozoite (with RBC’s in the cytoplasm) or cysts (with up to 4 nuclei) in stool
Treatment for Amebiasis?
Metronidazole; use iodoquinol for asymptomatic cyst passers
What are the symptoms of a Cryptosporidium infection?
Severe diarrhea in AIDS Mild disease (WATERY diarrhea) in immunocompetent
How is Cryptosporidium transmitted?
Oocysts in water
What is unique about Cryptosporidium lifecycle?
Does not need to use an insect host and can complete an entire lifecycle inside a single host which results in cyst stages that are excreted and can be transmitted to a new host
How do you diagnose Cryptosporidium?
Oocysts on acid-fast stain
What is the treatment for a Cryptosporidium infection?
Mainly symptomatic (hydration therapy, electrolyte management, pain management, etc.)
Prevent by filtering city water supplies
Use Nitazoxanide in immunocompetent patients
What are the 3 protozoan CNS infections?
1) Toxoplasma gondii
2) Naegleria fowleri
3) Trypanosoma brucei
What are the symptoms of Toxoplasma gondii infection?
Brain abscess in HIV (ring enhancing lesions on CT/MRI)
What are the symptoms of congenital toxoplasmosis? (another triad…)
“Classic triad” of
1) Chorioretinitis
2) Hydrocephalus
3) Intracranial calcifications
How is toxoplasmosis transmitted?
Cysts in meat or oocysts in cat feces; Crosses placenta (classic presentation is a pregnant woman who is taking care of a cat)
How do you diagnose toxoplasmosis?
Serology, biopsy (see tachyzoite)
How do you treat toxoplasmosis?
Sulfadiazine + Pyrimethamine
What happens with a Naegleria fowleri infection?
Rapidly fatal meningoencephalitis
How is Naegleria fowleri transmitted?
By swimming in freshwater lakes
Nalgene bottle filled with Fresh Water contains Naegleria
What part of the body does Naegleria fowleri enter through?
Cribiform plate
How do you diagnose a Naegleria fowleri infection?
Amoebas in spinal fluid
How do you treat Naegleria fowleri?
Amphotericin B (effective for few)