microbio parasitology Flashcards
giardia
bloating, flatulence, foul-smelling, fatty diarrhea (often seen in campers/hikers); transmitted by cysts in water; diagnose by trophozoites or cysts in stool; treat with metronidazole
entamoeba histolytica
cause of amebiasis; bloody diarrhea (dysentery), liver abscess (anchovy paste exudate), RUQ pain; histology shows flask-shaped ulcer; transmitted by cyst in water; dx in serology and/or trophozoites or cysts in the stool; treat with metronidazole (or iodoquinol for asymptomatic cyst passers)
cryptosporidium (DIFFERENT from cryptococcus)
severe diarrhea in AIDS; mild disease (watery diarrhea) in immunocompetent hosts; dx by oocytes on acid-fast stain; transmitted by oocysts in water; prevent by filtering city water supplies; treat with nitazoxanide in immunocompetent hosts
toxoplasma gondii
congenital toxo has classic triad of chorioretinitis, hydrocephalus, and intracranial calcifications; reactivation in AIDS leads to brain abscess seen as ring enhancing lesions on CT/MRI; transmitted by cysts in meat, oocytes in cat feces (crosses placenta); diagnosis by serology, bx (tachyzoite); treat with sulfadiazine and pyrimethamine
naegleria fowleri
rapidly fatal meningitis; get by swimmin in freshwater lake; enters via cribiform plate; dx by amoebas in spinal fluid; treat with amphotericin B (but usually they die)
trypanosoma brucei
African sleeping sickness; enlarged lymph nodes, recurring feer, somnolence, coma; carried by the tsetse fly, a painful bite; dx on blood smear; treat with suramin fro blood-borne disease or melarsoprol for CNS penetration
plasmodium (vivax, ovale, falciparum, malariae)
malaria (fever, HA, anemia, splenomegaly); p.vivax/ovale has 48 hr cycle for fever, dormant form in liver; p. faliparium has severe disease, irreg fever patterns, parasitized RBCs occlude capillaries in brain (cerebral malaria), kidney, lungs; p. malariae has a 72 hr cycle for fever
p vivax/ovalle
48 hr fever
p. falciparum
irreg fever patterns
p. malariae
72 hours cycle patterns
how are the plasmodium transmitted
anopheles mosquito
how is malaria diagnosed?
blood smear showing trophozoite ring form within RBC, schizont containing merozoites; red granules throughout RBC cytoplasm seen in P. vivax/ovale
treatment of malaria
chloroquine (for sens species); if resistant, use mefloquine or atovaquone/proguanil
babesia
babesiosis (fever and hemolytic anemia; predominanlty in northeast US; asplenia increases risk of severe disease); transmitted by the Ixodes tick (so often coinfected with Lyme disease); bood smear shows ring form or maltese cross; treat with atovaquone and azithromycin
trypanosoma cruzi
Chagas disease (dilated cardiomyopathy with apical atrophy, megacolon, megaesoph predomnantly in south america); unilateral periorbital swelling characteristic of acute stage; transmitted by the Reduviid bug (kissing bug) feces, deposited in a painless bite (much like a kiss); diagnose on blood smear; treat with benznidazole or nifurtimox
leishmania donovani
Visceral leishmaniasis (spiking fevers, hepatosplenomegaly, pancytopenia); sandfly; diagnose by macrophages containing amastigotes; treat with amphotericin B, sodium stibogluconate
trichomonas vaginalis
vaginitis (foul-smelling, greenish discharge; itching and burning); do not confuse with Gardnerella vaginalis (bacterium assoc with bacterial vaginosis); transmitted by sexual contact; diagnose by trophozoites on wet mount; “strawberry cervix”’ treat with metronidazole for patient and partner (prophylaxis)
what are the nematodes (roundworms)?
enterobius vermicularis (pinworm), ascaris lumbricoides (giant roundworm), strongyloides stercoralis, ancylostoma duodenale and necator americanus (hookworms), trichinella spiralis, onchocerca volvulus, loa loa, wuchereria bancrofti, toxocara canis
enterobius vermiculars
fecal-oral transmission; intestinal infection causing anal pruritis (diagnosed by seeing egg on the tape test); treat with bendazoles
ascaris lumbricoides (giant roundworm)
fecal-oral; eggs visible in feces under microscope; intestinal infection with possible obstruction at the ileocecal valve; treat with bendazoles
strongyloides
larvae in soil penetrate the skin; intestinal infection causing vomitting, diarrhea, epigastric pain; treat ivermectin or bendazoles
ancylostoma duodenale and necator americanus (hookworms)
transmitted by larvae penetrating the skin; intestinal infection causing anemia by sucking blood from the intestinal walls; treat with bendazoles or pyrantel pamoate
trichinella spiralis
fecal-oral; undercooked meat (esp pork); intestinal infections; larvae enter the bloodstream and encyst in striated muscle cells (leading to inflamm of muscle); trichinosis is fever, vomiting, periorbital edema, myalgia; bendazoles
onchocera volvulus
get from the female blackfly bite; causes hyperpigmented skin and river blindness; treat with ivermectin
loa loa
get from the deer fly, horse fly, or mango fly; causes swelling in the skin, worm in conjunctiva; tx with diethylcarbamazine
wuchereria bancrofti
get from the female mosquito; causes elephantiassis (worms block lymphatic vessels, takes 9 mos after bite to become symptomatic); treat wth diethylcarbamazine
toxocara canis
fecal-oral; visceral larva migans; treat with bendazoles
nematode (round worm) routes of infection
ingested are enteribius, ascaris, toxocara, trichinella; cutaneous are strongyloides, ancylostoma, necator; bites are loa loa, onchocerca volvulus, and w. bancrofti
what are the cestodes (tapeworms)?
taenia solium, diphyllobathrium latum, echinococcus granulosus
taenia solium
two types of infection; the first is from ingestion of the larvae in undercooked pork, which is an intestinal infection that is treated with praziquantel; the second is ingestion of eggs that causes cysticercosis and neurocystercicosis and is treated with praziquantel also but albendazole fro neurocysticercosis
diphyllobothrium latum
get from ingestion of larvae from raw freshwater fish; causes a vit B12 def (tapeworm competes from B12 in intestine) leads to megaloblastic anemia; treat with praziquantel
echinococcus granulosus
ingestion of eggs from dog feces (sheep are intermediate host); causes hydatid cysts in liver, causing anaphylaxis if antigens released (so the cyst must be injected with ethanol or hypertonic saline to kill daughter cysts before removal); treat with albendazole
what are the trematodes (flukes)?
schistosoma and clonorchis senensis
schistosoma
snails are host; penetrate skin of humans; liver and spleen enlargment (s. mansoni), fibrosis and inflamation; chronic infection with s. haematobium can lead to squamous cell carcinoma of the bladder (painloess hematuria) and pulmonary hypertension; treat with praziquantel
clonorchis sinensis
get from undercooked fish; biliary tract inflamm leads to pigmented gallstones; assoc w cholangiocarcinoma; treat with praziquantel
parasite assoc with biliary tract disease, cholangiocarcinoma
clonorchis sinensis
parasite assoc with brain cysts and seizures
taenia solium
parasite assoc with hematuria, squamous cell carcinoma of the bladder
schistosoma haematobium
parasite assoc with liver (hydatid) cysts
echinococcus granulosus
parasite assoc with microcytic anemia
ancylostoma, necator
parasite assoc with myalgias, periorbital edema
trichinella spiralis
parasite assoc with perianal pruritis
enterobius
parasite assic with portal hypertension
schisto mansoni, schisto japonicum
parasite assoc with vit B12 def
diphyllobothrium latum
