Malaria Module Flashcards
(54 cards)
In what areas of the world is malaria endemic?
AFRICA
but also part of Asia and Latin America
The few cases that occur annually in the US are generally from what source?
contaminated blood transfusions - malaria is a disease we don’t screen for
What causes malaria?
a protozoa called plasmodium
What is hemozoin?
It’s a crystallized pigment that the plasmodium creates as a byproduct when it eats hemoglobin
WHY does the parasite form hemozoin?
the first break down product of eating hemoglobin is hematin, which is toxic. So it turns hematin to hemazoin which is nontoxic.
How is malaria spread?
the anopheles mosquito
What’s the stereotypical histology picture of malaria?
A RBC with ring strucutres = trophozoites
What are the four species of plasmodium we’re concerned about for humans?
- plasmodium vivax
- plasmodium ovale
- plasmodium malariae
- plasmodium falciparum
Which species causes the worst disease/is most deadly? Why?
falciparum - it causes the highest parasite burden because it doesn’t care what stage the RBCs are in. Leads to severe anemia - it’s capable of entering the brain and has multi-organ symptoms
very high fatality rate
Why are the three other species less deadly?
they don’t cause as high a parasite load, so the anemia is much milder
Which two species can cause relapse? How?
vivax and ovale
They form hypnozoite forms that lay dormant in the liver for years
What two species are most common? Where?
vivax = everywhere but africa falciparum = africa
What form is the parasite in when the mosquito injects it into the human?
sporozoites
What’s the first cell the sporozoites infect?
hepatocytes
What does the parasite do in the hepatoctes?
proliferates and forms a schizont
What eventually happens to the schizont?
When it’s large enough, it will rupture, releasing the “babies” as merozoites
Merozoites re-enter the blood and infect what cells?
RBCs
What do the merozoites form in the RBCs?
trophozoites = the ring structures
What does the trophozoite develop into?
Another schizont with merozoites inside
Some of the merozoites that are released from the schizont will then go to infect other RBCs, but others will do what?
Form gametocytes, which will be picked up in the blood by another anopheles mosquito that comes along - then they will undergo sexual reproduction in the mosquito
How can you differentiate the falciparum species from the others?
In the gametocyte stage, they aren’t round like the others - they’re shaped more like a banana
How can you differentiate vivax and ovale from the other two?
vivax and ovale have dark schuffner’s dots in the cytoplasm
What two red cell pathologies are caused by a falciparum that leads to blocked capillaries?
- they form rosettes - an infected RBC surrounded by three healthy RBCs - these clump together and block capillaries
- Proteins secreted by the parasite make the outside of the cell all “bumpy” and they exhibit abnormal binding tot he endothelial walls, causing blockage as well
What’s the main cause of death with falciparum infection in children?
cerebral ischemia
