Additional bugs (those not provided by sketchy) Flashcards
What is unique about plasmodia reproduction?
Sexual reproduction in arthropod vs asexual reproduction in humans RBCs
Asexual repro in RBCs resulting in bursting of the RBC and thus causes cyclical symptoms of fever and anemia
What are the 3 characteristic features that allow ID of plasmodia (in general) in a blood smear?
1) red nuclear chromatin
2) blue cytoplasm
3) brownish-black malarial pigment (hemozoin)
What is the identifying quality of P. vivax and P. ovale infected RBCs on a smear?
Pale, Enlarged, w/ many Schuffner’s dots.
- all asexual stages (trophozoite, schizont, merozoite) can be seen simultaneously*
- P. ovale are more elongated and irregularly shaped (fimbriated)*
What is unique about RBCs infected with P. malariae?
not enlarged and contain no granules…
merozoites arranged in rosettes around a clump of central pigment
What do RBCs infected w/ P. falciparum look like?
Rings are very small and contain 2 chromatin dots rather than one (headphone appearance)
often more than 1 parasite per cell
intracytoplasmic granules known as Maurer’s dots may be present
gametocytes are large and banana shaped
Which strains of malaria cause hepatic dormancy?
P. vivax & P. ovale
How are some people (west african descent) immune to P. vivax?
P. vivax RBC receptor is the Duffy antigen. Most persons of West African descent Duffy negative so there is no way for P. vivax to enter the RBC
What genetic factor limits the parasitemia of P. falciparum?
Sickle cell anemia. RBCs heterozygous for hemoglobin S appear to retard parasite growth and may induce phagocytosis of the misshapen RBC and thus parasite too.
What is a different between the malaria parasite and vertebrate cells that is very useful to selectively target parasites?
Malarial parasites synthesize folates de novo whereas our cells require vitamin intake to make folic acid. SO… an antifolate drug like pyrimethamine is effective antimalarial
Epi… where are each species of malaria found?
P. vivax = most widely distributed… and together with the more uncommon P. malariae they are found in temperate and subtropical areas.
P. falciparum = tropics
P. ovale = rare and found only in Africa
Which strain of malaria can impair microcirculation and precipitate tissue hypoxia, lactic acidosis, and hypoglycemia?
P. falciparum… It causes the most severe parasitemia and thus the RBCs can deposit on the endothelium causing mirco-blockages which also cause cerebral malaria
What is the average time to onset of malaria symptoms? and what are the exceptions?
normally within 2 weeks…
25% of falciparum can take a month
25% vivax can take 6 months!
What is treatment of acute malaria infection?
Treatment for dormant malaria infection (radical cure)?
Acute = chloroquine (inhibits the degradation of hemoglobin which is the malarial source of iron for survival)
Dormant (radical) = primaquine for those pesky P. vivax and P. ovale that like to hang out forever in hepatocytes. Gotta check for G6PD deficiency before treating otherwise you will cause RBC lysis!
Which strain of malaria should be assumed to be chloroquine resistant?
P. vivax acquired in * New Guinea or Sumatra* and should be treated with mefloquine
(some p. falciparums are not resistant to chloroquine and should be treated with artemisinins in combo w/ quinines)
What are characteristic E. Coli properties that allow you to identify it?
G- bacilli (thus it has LPS endotoxin)
Lactose fermenter
Oxidase –
