Pathogenic Protozoa Flashcards
Describe the transmission, symptoms and treatments for: Giardia Lambdia
Tsm: unfiltered water, fecal/oral spread;
Cx: Backpacker’s Diarrhea;
Tx: Metronidazole
Define the diagnostic tools to detect Giardia in stool of infected patients?
ELISA stool antigen, IFA or Iodine staining
Describe the transmission, symptoms and treatments for: Entameoba histolytica
Tsm: fecal/oral spread by water/food;
Cx: Amoebic Dysentery; “anchovy paste abscesses” (no need to drain them)
Tx: Metronidazole, Paramycin, Chloroquine
Describe the diagnostic features someone might find in abscesses of someone infected with Entamoeba?
Ingested RBCs within trophozoites under a microscope; ELISA stool antigen or serology for ABs against infection
Describe the transmission, symptoms and treatments for: Toxoplasma gondii
Tsm: oocytes shed in cat feces, transplacentally to fetus;
Cx: Severe neurological and ocular disease in fetus;
Tx: Sulfadiazine, Pyrimethamine
An HIV patient presents with chronic watery diarrhea. Specialized microscopy of his stool revealed acid-fast cysts. What parasite is he suspected to be infected with?
Cryptosporidium, treated with Nitazoxinide
Briefly describe a key feature of each of the subspecies of Trypanosoma brucei.
- T. b brucei = disease in livestock, recurrent fevers;
- T. b. rhodesiense = East African RAPID-progressing disease;
- T. b. gambesiense = West African slowly-progressing disease
Describe the transmission, symptoms and treatments for: Trypansoma brucei
Tsm: tsetse fly;
Cx: Cervical and Axillary lymphadenopathy, recurrent fevers;
Dx: Trypomastigotes in blood smear;
Tx: Melarsoprol (CNS infection), Suramin (peripheral blood infection)
What key feature about Trypanosoma brucei enables it to escape the immune system to cause chronic infection?
Variable surface glycoprotein coats (VSGs) that undergo constant antigenic variation.
What are the 2 treatments recommended for African Sleeping Sickness?
Treatments for Trypanosoma brucei include:
- Suramin - peripheral “serum” blood infection
- Melarsoprol - CNS infection
Describe the transmission, symptoms and treatments for: Trypanosoma cruzii “Chagas Disease”
Tsm: scratched feces of Kissing bug;
Cx: Megacolon, Dilated cardiomyopathy;
Dx: Blood smear, serology, muscle biopsy, PCR;
Tx: Benznidazole, Nifurtimox
What are the 2 treatments recommended for Chagas Disease?
Treatments for Trypanosoma cruzii include:
- Benznidazole - nitroimidazole derivative;
- Nifurtimox - increase oxidative stress
What are the symptoms of Chagas Disease? What of the diagnostic features?
- Megacolon, Mega-esophagus, Dilated Cardiomyopathy
2. Intracellular amastigotes in heart muscle
Describe the transmission, symptoms, diagnostics and treatments for: Leishmaniasis
Tsm: Female sandfly;
Cx: Cutaneous, visceral or mucosal symptoms, hepatosplenomegaly;
Dx: Leishman-Donovan bodies (amastigotes in tissue);
Tx: Miltefosine, Amphotericin B
Describe the transmission, symptoms, diagnostics and treatments for: Naegleria
Tsm: freshwater exposure, sinuses to brain via olfactory nerves;
Cx: SEVERE keratitis, FATAL amoebic meningoencephalitis;
Dx: trophozoites in CSF, brain biopsy, immunoflourescence;
Tx: Amphoterecin
Describe the transmission, symptoms, diagnostics and treatments for: Babesia
Tsm: Ixodes Tick;
Cx: hemolytic anemia, jaundice; irregularly cycling fevers
Dx: Ring form cell, Maltese-cross RBCs from trophozoites.
Tx: Azithromycin, Atovaquone
A patient presents in the clinic with jaundice from a tick bite he got some weeks ago. He’s been feeling fatigued and feverish lately. What disease might he have if Lyme disease is ruled out? What are the recommended treatments?
Babesiosis - marked by Maltese-cross RBCs in blood smear. Atovaquone and Azithromycin are recommended treatments.
What human alleles result to some resistance against malarial symptoms? (List at least 3).
- Sickle cell disease (HbS)
- G6PD deficiency (heterozygotes)
- Duffy-negative (lack of blood group antigen for P. vivax)
Out of the 4 plasmodium subspecies, which one is the deadliest and why? Which one has 72-hour interval fevers?
- P. falciparum = most severe with cerebral involvement
2. P. malariae = 72-hour fever intervals (compared to the other 48-hour intervals)
What are the 2 recommended treatments for Plasmodium falciparum?
Artemisins and Atovaquone
Describe the effect of chloroquine phosphate as an anti-malarial drug.
Chloroquine is a low-cost, oral drug that is effective for blood schizonts but not liver stage parasites, P. vivax or P. ovale hypnozoites. “Beaded necklaces” = prevent polymerization of hemoglobin breakdown + heme buildup that’s toxic to parasite.
Describe the effect of Primaquin as an anti-malarial drug.
Primaquin is effective against the liver stage of ALL 4 PLASMODIA SPECIES, even hypnozoites of P vivax and P ovale. “Fierce primal queen” = Forms quinoline metabolites that acts as cellular oxidants in combo with chloroquine
Describe the effect of Mefloquin as an anti-malarial drug.
Mefloquin is recommended for CHLOROQUINE-RESISTANT strains of P falciparum. It is not effective against hepatic stages of gametocytes. “Me-fly-queen on the palanquin”
What antimalarial drug acts as a First-line drug for P falciparum?
Quinine and Quinidine from the Cinchona tree = highly effective against blood schizonts of all 4 types of plasmodia and gameticidal against P vivax and ovale. Prevents DNA replication and RNA transcription.
Describe the effect of Malarone as an anti-malarial combination drug.
Malarone = atovaquone + proguanil that is highly effective against persistent liver stages of P vivax or P ovale. Disrupts mitochondrial electron transport of the parasite.
What are the 5 antibiotics used to treat all erythrocytic forms of all species.
- Tetracycline
- Doxycycline
- Clindamycin
- Azithromycin
- Fluoroquinolones
What stage of the malaria lifecycle is most susceptible to the host’s immune response, which involves the release of antibodies? What is the clinical significance of this?
Sporozoite stage which starts the initial round of infections within RBCs only lasts 30 minutes at a time but is most susceptible. Malarial vaccines are impractical (since sporozoites cannot grow well in culture)
Describe the transmission, symptoms, diagnostics and treatments for: Cyclospora
Tsm: fecal/oral, outbreaks from contaminated fruits/veggies;
Cx: Diarrhea (hospitalization if severe);
Dx: Acid-fast stained cysts
Tx: TMP-SMX, supportive care
Describe the transmission, symptoms, diagnostics and treatments for: Cryptosporidium parvum
Tsm: contaminated water;
Cx: chronic watery diarrhea in AIDS patients, fever and GI pain;
Dx: Acid-fast oocysts in fecal smear
Tx: Nitazoxinide, Spiramycin, chlorination/filtration removes cysts from water
Describe the transmission, symptoms, diagnostics and treatments for: Microsporidia
Tsm: contaminated water, in compromised patients;
Cx: intestinal, eye and systemic infections;
Dx: stained specimens, hard to detect/distinguish;
Tx: Albendazole (MT inhibitor), Fumigillin (methionine aminopeptidase inhibitor)
Describe the transmission, symptoms, diagnostics and treatments for: Trichomonas vaginalis
Tsm: most common pathogenic protozoan in industrialized countries;
Cx: Vaginitis in females; Urethritis/ Epididymitis in males;
Dx: Motile trophozoite on wet mount (no cyst stage!)
Tx: Metronidazole, Tinidazole (treat both partners)
Describe the mode at which Chloroquine works as an anti-malarial drug.
Kills erythrocytic schizonts/ merozoites. Administer 4 weeks after leaving endemic area so ALL stages revert to more sensitive forms (sporozoites) in the blood.
