Parasitology Flashcards
Giardia lamblia
GI infection
bloating, flatulence, foul-smelling, fatty diarrhea (often seen in campers/hikers)
Transmission: cysts in water
Diagnosis: trophozoites or cysts in stool
Treatment: metronidazole
Entamoeba histolytica
GI infection
bloody diarrhea, liver abscess (“anchovy paste” exudate), RUQ pain (histology shows flask-shaped ulcer if submucosal abscess of colon ruptures)
Transmission: cysts in water
Diagnosis: serology and/or trophozoites (with RBC in cytoplasm) or cyst with multiple nuclei in stool
Treatment: metronidazole; iodoquinol for asymptomatic cyst passers
Cryptosporidium
GI infection
severe diarrhea in AIDS
mild disease (watery diarrhea) in immunocompetent
Transmission: cysts in water
Diagnosis: cysts on acid-fast stain
Treatment: prevention (filtering water); nitazoxanide in immunocompetent hosts
Toxoplasma gondii
CNS infection
brain abscess in HIV (ring-enhanced lesions)
congenital toxoplasmosis = chorioretinitis, hydrocephalus, intracranial calcification
Transmission: cysts in meat or cat feces; crosses placenta (pregnant women should avoid cats)
Diagnosis: serology, biopsy
Treatment: sulfadiazine + pyrimehamine
Naegleria fowleri
CNS infection
rapidly fatal meningoencephalitis
Transmission: swimming in freshwater lakes; enter via the cribriform plate
Diagnosis: amoebas in spinal fluid
Treatment: amphotericin
Trypanosoma brucei, T. gambiense, T. rhodesiense
CNS infection
African sleeping sickness: enlarged lymph nodes, recurring fever (due to antigenic variation), somnolence, coma
Transmission: tsetse fly, painful bite
Diagnosis: blood smear
Treatment: suramin for blood-bourne or melarsopol for CNS penetration
Plasmodium
hematologic infection
fever, headache, anemia, splenmegaly
P. vivax/ovale - 48 hour cycle; dormant form in liver
P. falciparum - severe; irregular fever patterns; parasitized RBCs occulde capillaries in brain (cerebral malaria), kidneys, lungs
P. malariae - 72 hr cycle
Transmission: mosquito (Anopheles)
Diagnosis: blood smear, trophozoite ring form, RBC schizont with merozoites
Treatment:
chloroquine (blocks Plasmodium heme polymerase); if resistant use mefloquine;
if life-threatening –> IV quinidine
Vivax/ovale - add primaquine for hyponozoite
Babesia
hematologic infection
fever and hemolytic anemia; predominately in NE US
asplenia increases risk of severe disease
Transmission: Ixodes tick
Diagnosis: blood smear, ring form, “Maltese cross” (X); PCR
Treatment: atovaquone + azithromycin
Trypanosoma cruzi
visceral infection
Chagas’ disease; dilated cardiomyopathy; megacolon, megaesophagus; predominantly in South America
Transmission: Reduviid bug, painless bite
Diagnosis: blood smear
Treatment: nifurtimox
Leishmania donovani
visceral infection
visceral leishmaniasis: spiking fevers, hepatosplenomegaly, pancytopenia
Transmission: sandfly
Diagnosis: macrophages containing amastigotes
Treatment: sodium stibogluconate
Trichomonas vaginalis
STD
vaginitis: foul-smelling, greenish discharge, itching and burning
Transmission: sexual
Diagnosis: trophozoites (motile) on wet mount
Treatment: metronidazole for patient and partner
Enterobius vermicularis
intestinal pinworm
intestinal infection cause anal pruritus (diagnosed by Scotch Tape test)
Transmission: food contaminated with eggs
Treatment: bendazoles or pyrantel pamoate
Ascaris
intestinal giant roundworm
intestinal infection
Transmission: fecal-oral; eggs visible in feces under microscope
Treatment: bendazoles or pyrantel pamoate
Strongyloides stercoralis
intestinal roundworm
intestinal infection causing vomiting, diarrhea, anemia
Transmission: larvae in soil penetrate skin
Treatment: ivermectin or albendazole
Ancylostoma duodenale, Necator americonus
intestinal hookworms
intestinal infection causing anemia by sucking blood from intestinal walls
Transmission: larvae penetrate skin
Treatment: bendazoles or pyrantel pamoate
Dracunculus medinensis
tissue roundworm
skin inflammation and ulceration
Transmission: in drinking water
Treatment: slow extraction of worm
Onchocerca volvulus
tissue roundworm
hyperpigmented skin and river blindness; allergic reaction to microfilaria possible
Transmission: female blackfly bite
Treatment: ivermectin
Loa loa
tissue roundworm
swelling in skin, worm in conjunctiva
Transmission: deer fly, horse fly, mango
Treatment: diethylcarbamazine
Wuchweweia bancrofti
tissue roundworm
blocks lymphatic vessels: elephantiasis; takes 9 months-1 years after bite to become symptomatic
Transmission: female mosquito
Treatment: diethylcarbamazine
Toxocara canis
tissue roundworm
visceral larva migrans
Transmission: food contaminated with eggs
Treatment: albendazole or mebendazole
Taenia solium
tapeworm
ingestion of larvae encysted in undercooked pork –> intestinal infection
ingestion of eggs –> cysticerosis; neurocysticerosis
Treatment: praziquantel; bendazoles for neurocysticercosis
Diphyllobothrium latum
tapeworm
Vitamin B12 deficiency –> anemia
Transmission: ingestion of larvae from raw freshwater fish
Treatment: praziquantel
Echinococcus granulosus
tapeworm
cysts in liver, causing anaphylaxis if antigens released (surgeons preinject with ethanol to kill cysts before removal)
Transmission: ingestion of eggs from dog feces
Treatment: bendazoles
Schistosoma
flukes
liver and spleen granulomas, fibrosis, and inflammation; chronic infection can lead to squamous cell carcinoma of the bladder
Transmission: snails are host; cercariae penetrate skin of humans
Treatment: praziquantel
