Parasitology I – Flashcards
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| What are the two major groups of parasites? |
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| protozoa and helminths |
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| What percentage of the world's population has amebiasis? |
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| 10% |
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| What are examples of sporozoa? |
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| cryptosporidium hominis, toxoplasma gondii (plasmodium species) |
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| What are examples of Rhizopods? |
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| naeglaria and acanthamoeba (entamoeba histolytica) |
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| What are examples of the flagellates? |
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| trichomonas vaginalis, giardia lamblia, leishmania, trypanosoma |
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| What are the diferent types of protozoa? |
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| sporozoa, rhizopods and flagellates |
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| Where are the oocysts of crptosporidium hominis found? |
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| worldside in poop of domestic animals and people. Can enter drinking water supply, causing outbreaks |
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| Cryptosporidium hominis is resistent to.... |
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| chlorine treatment and freezing |
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| What do the infective oocysts of cryptosporidium hominis do once they are ingested? |
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| land in microvilli and sporozoites excyst and invade epithelial cells |
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| What are the symptoms of cryptosporidium hominis? |
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| week of watery, profuse diarrhea with mild malabsorption/weight loss |
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| how do you treat cryptosporidium hominis? |
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| self-limiting in immunocompetent. Fluid and electrolytes in immunocompromised patients |
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| Where is toxoplasma gondii found? |
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| cat poop and raw meat |
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| What is the prevalence of toxoplasma gondii? |
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| 50% of adults in US |
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| What are the symptoms of toxoplasma gondii? |
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| self-limiting febrile adenopathy; usually chronic, assymptomatic can mimic infectious mononucleosis. Can be highly lethal: AIDS patients develop encephalitis |
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| What does toxoplasma gondii do to fetuses? |
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| malformations, chorioretinitis, stillbirths |
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| How do you diagnose toxoplasma gondii? |
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| primary method: agglutination IFA with antibodies to toxoplasma PCR in congenital or AIDS pts histopathology via lymph node biopsy |
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| What is the treatment for toxoplasma gondii? |
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| no treatment for normal people. For immunocompromised/pregnant you use pryimthamine and sulfonamides (Pryimethmamine is teratogenic and spiramycin should be used in place of pyrimethmamine in the first trimester |
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| What organism causes malaria? |
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| plasmodium |
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| In what form does plasmodium enter a liver cell? leave a liver cell? after it enters the RBC? |
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| sporozoite; merozoite; trophozoite |
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| What are the symptoms of plasmodium infection? |
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| fevers, h/a, sweats, dark urine (hemoglobinuria) |
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| What might you find on physical exam of a person with malaria? |
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| splenomegally |
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| Which is the most dangerous type of plasmodium and what are the mechanism by which it causes morbidity/mortality? |
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| P. falciparum; anemia depressed bone marrow function, capilliary blockage in the brain and reduced blood flow to vital organs |
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| How do you diagnose plasmodium? |
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| parasitized RBCs usually visualized by microscopic examination of blood smears stained with Wright's or Giemsa stain ALSO, card-based antigen detection test: OptiMAL |
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| How do you treat plasmodium infection? |
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| chloroquine, antifolate-sulfonamide combinations, mefloquine, halofantrine, artemisinin-based combination therapy (ACT) with mefloquine |
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| How do the Negleria and Acanthamoeba cause disease? |
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| enters nasal mucosa, cribiform plate into central nervous system, severe hemorrhagic inflammation |
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| What are the symptoms of naegleria and acanthamoeba infection? |
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| high fever, bi-frontal h/a, stiff neck, smell/taste anomalies, seizures, coma, death |
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| What does the CSF look like in Naegleria infection? |
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| bloody with neutrophils and Naegleria trophozoites |
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| How do you treat naegleria and acanthamoeba infections? |
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| amphotericin B, miconazole and rifampin |
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| Entamoeba histolytica cysts can survive ______ treatments used in municipal water supplies. |
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| chlorine |
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| Where in the human body do entamoeba histolytica live? |
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| lumen or wall of colon |
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| What do entamoeba histolytica eat? |
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| bacteria and tissue cells in colon |
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| What are the symptoms of entamoeba histolytica infection? |
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| minimal/asymptomatic. Intermittant diarrhea, flatulence Ameobic dysentary can occur (abdominal cramping, high fever, blood and mucus in stool) |
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| Besides inhibiting the colon, what other organs can the entamoeba histolytica infect? |
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| -can infect liver, lung, spleen heart and brain |
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| An abscess in the liver that produces "anchovy paste" aspiration is most likely caused by which protozoan? |
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| the rhizopod, entomoeba histolytica |
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| What does the entamoeba histolytica rhizopod do to the mucosa? |
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| causes flask shaped mucosal ulceration |
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| How do you diagnose Entamoeba histolytica? |
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| identify it in stool! (harder to diagnose when disease is extra intestinal) E. histolytica antigen tests and enzyme immunoassays now available to aid diagnosis |
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| What is the treatment for Entamoeba histolytica? |
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| metronidazole combined with diloxanide Dehydroemetine for severe extra intestinal infections |
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| What are the symptoms of trichomonas vaginalis in women? |
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| discharge, itching/burning, unpleasant odor, painful intercourse/urination, reddening of vagina and endocervical mucosa, petechial hemorrhages (red/purple spots) |
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| What are the symptoms of trichomonas in men? |
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| usually asymptomatic, dysuria, nonpurulent d/c, urethra and prostate are involved (soemtimes involves seminal vesicles and epididymis) |
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| How do you diagnose trichomonas vaginalis? |
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| unstained wet mounts of vaginal d/c or urethral exudate in men. Could see jerky parasite cell movements. H and E stain, IFA antibody stain, PCR |
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| How do you treat trichomonas vaginalis? |
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| metronidazole (flagyl) and tinidazole (but never use that in first trimester of pregnancy--teratogenic) |
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| Where in the human body does Giardia lamblia live? |
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| duodenum and jejunum. Form infectious cysts in colon |
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| Which protozoa are resistant to chlorine treatment? |
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| cryptosporidium hominis, entamoeba histolytica, giardia lamblia |
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| What is the most commonly identified intestinal parasite in the U.S.? |
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| giardia lamblia |
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| What are the symptoms of giardia lamblia? |
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| usually symptomatic: diarrhea lasting up to 4 weeks (foul-smelling, greasy stool), abdominal pain, nausea, and vomiting. Intestinal malabsorption with heavy parasite burden |
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| What does giardia do do the intestines? |
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| damages microvilli brush border |
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| How do you diagnose Giardia lamblia? |
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| identify cysts in stool, intestinal biopsies by iodine or Giemsa stain (sample weekly because organisms might be intermittant in chronic infection) reliable commercial immunoassays to detect parasites in stool |
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| What are the treatments ofr giardia lamblia? |
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| quinacrine hydrochloride and metronidazole less effective: furazolidone (liquid for children) and paromomycin (pregnant women in first trimester) |
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| What are the three different types of leishmania sp. infection? |
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| cutaneous (least severe), mucocutaneous, visceral (most severe) |
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| Cutaneous leishmania is characterized by... |
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| ulcers; painless craters with raised erythematous edges, usually self-heals |
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| Mucocutaneous leishmania is usually characterized by... |
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| painful, destructive, metastatic mucosal lesions of mouth, nose (weeks to years); fever, anemia, weight loss, and secondary bacterial infections |
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| Visceral leishmania is characterized by... |
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| delayed onset: fever, enlarged lymph nodes and liver, massively enlarged spleen, edema; usually fata if untreated |
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| How do you diagnose leishmania? |
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| microscopic evaulation of parasites. Smears from these samples are stained with Giemsa, H and E oor immunoperoxidase PCR is a sensitive test too. |
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| What is the treatment for Leishmania? |
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| pentavalent antimonials (glucantime, pentostam), amphotericin B (liposomal formulation), paromomycin, azoles (fluconazole) for cutaneous leishmanias DRUG TOXICITY TO PT IS PROBLEMATIC |
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| What causes leishmania infection? |
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| infection via sandfly bites |
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| How does trypanosoma cruzi get into the human body? |
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| triatomine bug bites and defecates. T cruzi parasites in bug feces are inoculated when host scratches bite site |
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| What are the symptoms of Trypanosoma cruzi? |
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| flu-like symptoms |
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| What tissues does trypanosoma cruzi infect? |
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| myocarditis, encephalitis, lymphadenopathy |
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| What might you find on physical exame of a patient with Trypanosoma cruzi? |
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| spleen and liver enlargement |
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| What are the sequale of a chronic form of trypanosoma cruzi (10-30 yrs)? |
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| heart disease, megacolon, megaesophagus |
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| How do you diagnose trypanosoma cruzi? |
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| detection of parasites in blood smear, parasite culture, complement fixation test, xenodiagnosis, PCR |
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| How do you treat trypanosoma cruzi? |
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| nifurtimox, benznidazole, allopurinol toxic side effects, not always successful |
