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USMLE parasitology

Entamoeba hystolytica Amoebae-ingestion of cysts from water or sexual intercourse -> intestinal symptoms or extraintestinal such as liver abscess or pericardial disease. Dx with cysts in feces. Tx metronidazol+iodoquinol; diloxanide, furoate, tinidazole, paromycin.
Giardia Lamblia flagellate-ingestion of cysts in water->intestinal infection only->steatorrhea smell stools with diarrhea. Dx-cysts in feces. Tx-metronidazole or tinidazole
trichomonas vaginalis flagellate-transmitted sexually to infect the vagina and urethra causing pruritis, strawbery mucosa, greenish discharge, corkscrew motility on wet mount. Dx-trophozoites on wet mount. Tx- metronidazole+tinidazole
Naegleria fowleri Flagellate- infects nasal passage from diving in water. causes amoebic meningoencephalitis. Dx-trophozoites in CSF.
Acanthamoeba culbertsoni Flagellate- Infects skin, eyes, lungs, and other tissues; especially in immunocompromised persons that may cause granulomatous encephalitis.
Trypanosoma gambiense and trypanosoma rhodesiense Haemoflagellates- African Sleeping sickness w/ amastigotes (w/in cells) and trypomastigotes (w/in plasma) that may affect the CNS. vector-tsetse fly. Tx- suramin, melarsoprol (if encephalitis).
Trypanosoma cruzi haemoflagellate- chagas' disease w/ megacolon, dilated cardiomyopathy, megaesophagus. vector reduviid bug (kissing bug). dx-amastigotes in cells and trypomastigotes in plasma. Tx-nifurtimox(non-chronic), suramin
Leishmania brasiliensis Haemoflagellate- musculocutaneous form that causes ulcers on skin and necrosis of nasal mucosa. Vector- phlebotomine sandfly. Dx-amastigotes in cells and trypomastigotes in plasma. Tx- miltefosine, topical paromomycin.
Leishmania donovanii Haemoflagellate-visceral= Kala Azar w/ pancytopenia, high output HF/myocarditis/pericarditis/irregular fever, weight loss/ hepatosplenomegaly/high aminotransferases/hypoalbuminemia. Dx-amastigotes in cells. Tx-pentosan/glucantine/allopurinol/ miltefosine
intestinal parasites associated with myocarditis, percarditis, pericardial effusions or cardiac tamponade. trichonella spiralis (trichinosis), Echinococcus granulosus (hydatid cyst), Taenia solium (cystocercosis)
Hookworm or tapeworm associated with anemia that may also cause cardiac pathology. Necator americanus (Fe), Acylostoma duodenale (Fe), Dyphyllobothrium latum (Vit B12)
endomyocardial fibrosis Helminth-associated chronic eosinophilia may lead to restrictive cardiomyopathy.
Babesia sporozoa Vector-Ixodes tick. Found in blood as schizogony (asexual cycle) in the intermediate host w/ maltese cross in RBCs. Presents w/ fever and hemolytic anemia. co-infection with borrelia burgdorferi
Toxoplasma gondii undercooked meat, fecal-oral cat feces, organ transplant are vectors. transplancental TORCH. Presents w/ flu like signs w/ latency. HIV encephalitis/chorioretinitis /myocarditis/pericarditis/CHF. schizogony in tissue. Tx- pyrimethonine/sulfadiazine
Wuchereria bancrofti & Brugia malayi vector-mosquitto. adult in lymphatics->produce microfilariae-> travel in blood & lymph->inflammatory Rx=elaphantitis. Dx-PBS, high eosinophils/IgE/antifilarial ab/IgG4/microfilariae, ELISA. co-infect wolbachia bacteria. Tx- DEC/albendazole/ivermectin
Loa Loa W. Africa. Vector-deer fly (chrysops). larva infect subdermal CT->mature->migrating worm RX->across eye. Rx to migrating and dead worms. chronic abcess-> granuloma-> fibrosis. Tx-Ivermectin/Albendazole
Onchocerca Volvulus Africa/S.America. largest cause of blindness. Vector-Black fly. Larvae infect subcutaneous CT-> nodules-> microfilariae cause skin dermititis and blindness. Dx-nodulectomy. Tx-DEC/ivermectin, suramin
Dracunculus medinensis Vector-Water flea (cyclops). larvae infect from contaminated water-> larvae develop to adults in subcutaneous CT-> skin eruptions. Dx-radiology or PE. Tx-metronidazole and/or thiabendazole.
Mansonella Ozzardi S. America/caribbean. Vector-Simulium black fly/culicoides midges. mild/asymptomatic headache, joint pains, pruritis, inguinal adenitis. No sheath.
Mansonella Perstans Africa/S America/Caribbea. Vector Culcoides midges. Mild/asymptomatic abdominal pain or transient skin swellings. No sheath.
Plasmodium Vivax Vector F. anopholes mosquito. 48 hr relapsing fever with relapsing latent infections due to hypnozoites. requires duffy antigen (FyaFyb). Dx-PBS, HRP2 detection, parasite LDH. Tx-quinine, artemisinin
Plasmodium Ovale Vector F. anopholes mosquito. 48 hr relapsing fever with relapsing latent infection due to hypnozoite. Dx-PBS (schizonts), HRP2 detection, parasite LDH. Tx-quinine, artemisinin
Plasmodium Malariae Vecotr F. anopholes mosquito. 72 hr relapzing fever and may cause recrudescence. Dx- PBS (schizonts/gametocytes, HRP2 detection, parasitic LDH. Tx- Quinine, artemisinin
Plasmodium falciparum Vector-F. Anopholes mosquito. Unpatterned relapsing fever w/ recrudescence. severe hemolytic anemia, jaundice, hepatosplenomegaly, pulmonary edema, CHF, hypoglycemia, dyserythropoiesis, blackwater fever, cerebral malaria. Tx-Quinine/artemisinin
Proquanil Prophylaxis and treatment with atovaquone (malarone). MOA-palsmodial dihydrofolate reductase inhbitor.
Malarone (atovaquone) Prophylaxis and treatment with of chloroquine-resistant multidrug resistant strains of P. falciparum and P vivax.
Primaquine Drug of choice for P vivax and P ovale latent infection w/ hypnozoites.exoerythrocytic schizonts, gametocytocidal, hypnozoitocidal (only one). G6PDHase deficiency contraindicated due to acute intravascular hemolysis and methemoglobinemia.
Severe P falciparum treatment Quinidine gluconate+antifolates or antibiotics (doxycyline or clindamycin)
Uncomplicated P falciparum treatment Chloroquine. If resistant than quinine and doxycycline or atovaquone/proguanil.
Chloroquine P vivax, P ovale, P malariae, and uncomplicated P falciparum. prophylaxis safe during pregnancy. MOA-intraerthrocytic forms only by increasing pH in food vacoules, prevents polymeization of heme, inhibits TNF-a. Resistance-transporter, pump
Chloroquine Side effects High doses can lead to hypotension, cardiac arrhythmias, and cardiac arrest. Confusion, convulsions, coma. retinopathy and ototoxicity when high doses are given w/o plasmodium infection.
Quinine/Quinidine alkaloids that concentrate in food vacuoles of plasmodium in RBCs to prevent formation of hemozoin. Resistance- pfmdr1 efflux pump. SE-tinnitus, high tone deafness, visual disturbances, dysphoria, N&V, postural hypotension, hypoglycemia, thrombocytopenia
Pyrimethamine Antifolate prophylaxis antimetabolite parasitic dihydrofolate reductase inhbitor to tx-mildly chloroquine resistant, and uncomplicated multi-drug resistant malaria (w/quinine). Resistance-DHFR target change.
sulfadioxine combinations (fansidar) Antifolate prophylaxis parasitic dihydrofolate reductase inhbitor to tx-mildly chloroquine resistant, and uncomplicated multi-drug resistant malaria (w/quinine). Resistance-DHFR target change.
Artemisinin (artesunate, artmether) standard tx of uncomplicated P falciparum and multi-drug resistant malaria, but not monotherapy. combo w/ amodiaquine, sulfadioxine-pyrimethamine & lumafantrine. Rapid schizonticide. MOA- inhbit Ca++/ATPase. SE- type I hypersensitivity. no pregnancy
Metronidazole Tx-Amebiasis, trichomoniasis, giardiasis, balantiasis, hepatic and extrahepatic amebic infections. diloxanide added 2 increase log-kill. prodrug w/ active metabolite depriving anaerobes of reducing equivalents. resistance-up [O2] or alter [redox molecule]
Nifurtimox Tx-Acute chagas disease, but not chronic disease states. MOA-Produces ROS's intracellularly. AE-common, dose-related and reversible uncluding seizures, polyneuritis, N&V, abdominal pain, and insomnia.
Sodium Stibogluconate heavy metal pentavalent antimonial compound used to treat cutaneous, mucosal and visceral leishmaniasis. SE- Cardiotoxiic
Paromomycin sulphate aminoglycoside antibiotic. luminal amebicide (superior to diloxanide if asymptomatic), cryptosporidiosis in AIDs, Giardia lamblia during pregnancy (metronidazole is usual)
Prophylaxis malarial treatment Chloroquine (not for resistant strains), mefloquine (not for resistant strains), doxycycline, proguanil+atovaquone (malarone), pyrimethamine-sulfadioxine (fansidar)
Treatment of Acute attacks of severe malaria Quinidine gluonate, quinine sulfate (most common), doxycycline, pyrimethamine-sulfadioxide, mefloquine.
Treatment of less severe but acute attacks of malaria Chloroquine (especially P. ovale and P. vivax), tetracycline, clindamycin
Treatment of liver staged malaria. Primaquine (best), proquanil, tafenoquine, tetracycline.
hypnozoite stage malarial treatment Primaquine and tefenoquine
Active against trematodes and cestodes. Praziquantel.
Microsporidium (life cycle, spores are ingested, inject sporoplasm in host cell, develop meronts, multiplies, forms spores, ruptures host cell. pigs/dogs/ chickens/ rabbits/ primats. water-borne. AIDs associated. Giemsa & chromotrope 2R stain.
Pinworms enterobius vermicularis most common helminth in US; Presents in young children w/ perianal itching
Ascaris lumbarcoides 5-12 inches long; fecal-oral transmission; eggs ingested, hatch in intestine; larvae cross bowel-> reach blood; larvae migrate to lung/trachea-> swallowed-> adult worms develop after 14 days in warmer areas; slower in cooler temps; adults live 1-2 yrs
Hookworm- Ancylostoma duodenale
Created by: 45203472



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