Protozoa Flashcards
Cryptosporidium
Chronic watery D in AIDS
Transmitted by oocytes in H2O or person to person
Filtration removes oocytes in water
Oocytes on modified acid fast stain of stool – bright red/pink
Giardia lamblia
Ingested cysts trophozoites that interfere w/ fat absorption
Acute, fatty, foul smelling diarrhea
Flatulence
Abdominal bloating
Pear sheaped trophozoites or cysts in stool
- 4 flagella, double nucleas – owel eye appearance
- tumble motility
Tx: metronidazole, tinidazole
Entamoeba histolytica
Amebiasis -> bloody diarrhea
“amoebic dysentery”
invades colon -> tissue damage can perforate colon
Flask shaped ulcer – narrow opening w/ wide submucosal ulceration
Fecal oral route
Dx: trophozoites or cysts in stool
Ingested RBCs
Cysts – multiple nuclei
Serology – AB against Entamoeba
Stool Ag
Liver abscess w/ RUQ pain
Tx:
Trophozoites: metronidazole, tinidazole
Cysts: iodoquinol or paromomycin
Trichomonas vaginalis
MC protozoal infection in US
Vaginalitis and foul smelling greenish vaginal discharge
Transmission – sexual activity
Wet mount of vaginal discharge – pear shaped, very motile – twitching motion
3Fs: Foul smelling discharge, flagella, flagyl (metronidazole)
elevated vaginal pH
Toxoplasma gondii
Handling cat feces or litter
Eating cysts in infected meat
TORCH infection
Causes congenital toxoplasmosis
- chorioretinitis
- hydrocephalus
- intracranial calcifications
dormant for life unless immune system compromised -> reactivation
-ring enhancing lesions
Dx:
Serology – Ab
-Toxoplasma IgM – acute; IgG reactivation
Bx for definitive dx – differentiates from primary CNS lymphoma
Tx: sulfadiazine + pyrimethamine + folinic acid
Naegleria foweleri
Amoeba causing rapidly fatal meningoencephalitis
Swimming in fresh water lakes
-enters nose, passes through cribriform plate into brain
tx: amphotericin B
African sleeping sickness
Trypanosoma brucei rhodiesiense
Trypanosoma brucei gamblense
Tsetse fly
Protozoa in blood stream: fever, enlarged LN, somnolence
Late stage infection: CNS
- encephalitis
- coma and death
Blood smear – long wispy organisms
Tx: Suramin – early blood borne dz
Melarsoprol – CNS involvement
Trypanosoma cruzi
Chagas Dz
S America
Reduviid bug – kissing bug
-painless bite, feces scratched into skin
Everything is BIG
Dilated cardiomyopathy
Megaesophagus
Mega colon
Dx: blood smear
Tx: Benznidazole
Nifutimox
Leishmainia donovani
Visceral leishmaniasis
Cutaneous leishmaniasis – slow healing ulcerating papules
Sandfly transmission
Spiking fevers, HSM, pancytopenia
Dx: amastigotes inside M0, lacks flagella
Tx:
Visceral: liposomal amphotericine B
Cutaneous: sodium stibogluconate
Babesia microti
Babesiosis
Trophozoite – ring form in RBC
Merozoite – “maltese cross” in RBC
Fever and hemolytic anemia
NE US
Ixodes tick – can have coinfection w/ Lyme dz
Tx: severe – quinine + clindamycin
Malaria types and sx
P. vivax and P. ovale: 48 hr cycle, dormant in liver, tx: primaquine
P. falciparum – most severe, MC in Africa
- sequestration of RBCs -> occlusion of small vessels
- > cerebral malaria, kidney, lung
P. malariae – 72 hr cycle
Cyclic sx: fever when RBCs rupture -> release merozoites into circulation
HA, anemia, splenomegaly
Malaria life cycle
Mosquito injects sporozoite
Sporozoites enter hepatocyte
-> Exoerythrocytic cycle: Early schizont -> late schizont -> merozoites rupture hepatocyte
Enter RBC -> erythrocyte cycle
Early trophozoite resembles diamond ring
Trophozoite -> early schizont -> late schizont -> merozoites released triggering fever and chills
-> gametocytes – mosquito drinks gametocytes
Plasmodium falciparum has banana shaped gametocyte
Malaria treatment
Chloroquine + primaquine (P. vivax or P. ovale)
Chloroquine resistant (most P. falciparum) Quinine + doxycycline Atovaquone – proguanil Artemether – lumefantrine Mefloquine
