Flashcards in Micro - Parasitology (Protozoa) Deck (55):
Which 3 protozoa cause GI infections? How is each transmitted?
(1) Giardia lamblia - Cysts in water (2) Entamoeba histolytica - Cysts in water (3) Cryptosporidium - Oocytes in water
What disease does Giardia lamblia cause? How does it present, and in patients with what kind of exposures?
Giardiasis: bloating, flatulence, foul-smelling, fatty diarrhea (often seen in campers/hikers); Think: "FAT-rich GHIRARDELLI chocolates for FATTY stools of GIARDIA"
How is Giardiasis diagnosed?
Trophozoites or cysts in stool
What organism causes Giardiasis? What is its treatment?
Giardia lamblia; Metronidazole
What disease does Entamoeba histolytica cause? How does it present?
Amebiasis: bloody diarrhea (dysentery), liver abscess ("anchovy paste" exudate), RUQ pain (histology shows flask-shaped ulcer if submucosal abscess of colon ruptures)
How is Amebiasis diagnosed?
Serology and/or trophozoites (with RBCs in the cytoplasm) or cysts (with multiple nuclei) in stool
What organism causes Amebiasis? What is its treatment?
Entamoeba histolytica; Metronidazole, Iodoquinol for asymptomatic cyst passers
What condition/disease(s) does Cryptosporidium cause, and in what patient population(s)?
Severe diarrhea in AIDS; Mild disease (watery diarrhea) in nonimmunocompromised
How is Cryptosporidium infection diagnosed?
Cysts on acid-fast stain
How is Cryptosporidium prevented? How is Cryptosporidium treated, and in what patient population(s)?
Prevention (by filtering city water supplies); Nitazoxanide in immunocompetent hosts
Which protozoa cause CNS infections?
(1) Toxoplasma gondii (2) Naegleria fowleri (3) Trypanosoma brucei, T. gambiense, T. rhodesiense
What major sign/symptom does Toxoplasma gondii cause in HIV patients?
Brain abscess in HIV (seen as ring-enhancing brain lesions on CT/MRI)
What are the signs/symptoms associated with congenital toxoplasmosis?
"Classic triad" of chorioretinitis, hydrocephalus, and intracranial calcifications
How is Toxoplasma gondii transmitted? What is an important implication of T. gondii transmission?
Cysts in meat or oocytes in cat feces; Crosses placenta (pregnant women should avoid cats)
How is Toxoplasma gondii diagnosed?
How is Toxoplasma gondii treated?
Sulfadiazine + Pyrimethamine
What condition/disease does Naegleria fowleri cause?
Rapidly fatal meningoencephalitis
How is Naegleria fowleri transmitted?
Swimming in freshwater lakes; Enters cribriform plate; Think: "NALGENE bottle filled with FRESHWATER containing NAEGLERIA";
How is Naegleria fowleri diagnosed?
Amoebas in spinal cord
What is a possible treatment for Naegleria fowleri?
Amphotericin has been effective for a few survivors
What disease does Trypanosoma brucei/T. gambiense/T. rhodesiense cause? What are its associated symptoms?
African sleeping sickness: enlarged lymph nodes, recurring fever (due to antigenic variation), somnolence, coma
How is Trypanosoma brucei/T. gambiense/T. rhodesiense transmitted?
Tsetse fly, a painful bite
What protozoa causes African sleeping sickness?
Trypanosoma brucei, T. gambiense, T. rhodesiense;
How is Trypanosoma brucei, T. gambiense, and T. rhodesiense diagnosed?
What is the treatment for Trypanosoma brucei, T. gambiense, and T. rhodesiense?
Suramin for blood-borne disease or Melarsoprol for CNS penetration; Think: "it SURe is nice to go to sleep, MELAtonin helps with sleep"
What disease does Plasmodium cause? What are its general symptoms?
Malaria; Fever, headache, anemia, splenomegaly
What are the different species of Plasmodium that can cause different kinds of malaria?
(1) P. vivax/ovale (2) P. falciparum (3) P. malariae
What characterizes malaria due to P. vivax/ovale?
48-hr cycle (tertian; includes fever on first day and third day, thus fevers are actually 48 hr apart); Dormant form (hypnozoite) in liver
What characterizes malaria due to P. falciparum?
Severe; Irregular fever patterns; Parasitized RBCs occlude capillaries in brain (cerebral malaria), kidneys, lungs
What characterizes malaria due to P. malariae?
72-hr cycle (quartan)
What protozoa causes Malaria? How is it transmitted?
Plasmodium (P. vivax/ovale, P. facliparum, P. malariae); Mosquito (Anopheles)
How is Malaria diagnosed?
Blood smear, trophozoite ring form, RBC schizont with merozoites
How is Malaria treated, and why? More specifically, explain treatment protocols in the following contexts: (1) First line therapy (2) If resistant to first line therapy (3) If life threatening (3) Vivax/Ovale.
Begin with chloroquine, which blocks Plasmodium heme polymerase; If resistance, use mefloquine or Atovaquone/Proguanil; If life-threatening, use intravenous quinidine (test for G6PD deficiency); Vivax/ovale - Add primaquine for hypnozoite (test for G6PD deficiency)
Which protozoa cause hematologic infections?
(1) Plasmodium (P. vivax/ovale, P. falciparum, P. malariae) (2) Babesia
What disease does Babesia cause? What are its symptoms?
Babesiosis: Fever and hemolytic anemia
Where is Babesiosis predominately found? What increases risk of severe disease?
Predominately in northeastern United States; Asplenia increases risk of severe disease
How is Babesia transmitted? What other pathogen has this same mode of transmission, and what disease does it cause? What is an important implication behind this commonality?
Ixodes tick; Same as Borrelia burgdorferi of Lyme disease, may often coinfect humans
How is Babesiosis diagnosed?
Blood smear, ring form, "Maltese cross"; PCR
What is the treatment for Babesiosis?
Atovaquone + Azithromycin
Which protozoa cause visceral infections that are NOT considered GI, CNS, or hematologic infections?
(1) Trypanosoma cruzi (2) Leishmania donovani
Which protozoa causes STDs?
What disease/condition does Trypanosoma cruzi cause? What are its associated symptoms?
Chagas' disease: Dilated cardiomyopathy, megacolon, megaesophagus
What pathogen causes Chagas' disease? Where is it predominately found? How is it transmitted?
Trypanosoma cruzi; Predominately in South America; Reduviid bug ("kissing bug"), a painless bite (much like a kiss)
Again, what pathogen causes Chagas' disease? How is it diagnosed?
Again, what disease/condition does Trypanosoma cruzi cause? What is its treatment?
Chagas' disease; Benznidazole or Nifurtimox
What condition/disease does Leishmania donovani cause? What are its associated symptoms?
Visceral leishmaniasis (kala-azar): Spiking fevers, hepatosplenomegaly, pancytopenia
What pathogen causes visceral leishmaniasis (kala-azar)? How is it transmitted?
Leishmania donovani; Sandfly
Again, what condition/disease does Leishmania donovani cause? How is it diagnosed?
Macrophages containing amastigotes
What is another name for visceral leishmaniasis? What pathogen causes it? How is it treated?
Kala-azar; Leishmania donovani; Amphotericin B, Sodium stibogluconate
What condition/disease does Trichomonas vaginalis cause? What are its associated symptoms?
Vaginitis: Foul-smelling, greenish discharge; Itching and burning
What other pathogen should you be careful not to confuse with Trichomonas vaginalis? How is this other pathogen characterized, and what disease/condition does it cause?
Gardnerella vaginalis, a gram-variable bacterium that associated with bacterial vaginosis
How is Trichomonas vaginalis transmitted? What is important to remember about its transmission?
Sexual (cannot exist outside human because it cannot form cysts)
Again, what condition/disease does Trichomonas vaginalis cause? How is it diagnosed?
Vaginitis; Trophozoites (motile) on wet mount; "Strawberry cervix"
What protozoa causes vaginitis? What is the treatment protocol for this condition?
Trichomonas vaginalis; Metronidazole for patient and partner (prophylaxis)