Malaria Flashcards
Classic morphological picture of malaria infected RBC?
ring form
Four species of malaria causing parasites?
Plasmodium
- vivax
- ovale
- malariae
- falciparum
Two most common species of Plasmodium?
vivax
falciparum
Most deadly species of Plasmodium?
falciparum
Two species of Plasmodium that can cause relapses:
vivax and ovale
**dormant in liver
Lifecycle stage of P. falciparum that enters human from mosquito? What cells does it infect first?
Sporozoites
hepatocytes
What stage of the parasite lifecycle is present in hepatocytes?
Hepatic schizonts
After hepatic shizonts, what stage of the parasite infects RBCs?
Merozoites
When a merozoite infects an RBC it undergoes three phase changes before becoming multiple merozoites able to infect more RBCs. What are the tree stages?
Ring form—> trophozoite—> schizont—> back to merozoites
Characteristic of P. falciparum in trophozoite stage?
lots of rings
shape of P. falciparum gametocytes?
crescent or banana
Characteristic of P. malariae schizonts?
rosette arrangement of merozoites
**apparently falciparum also forms rossetes by binding uninfected RBCs
Enlarged red cells in the trophozoite phase?
P. ovale
Schuffner’s dots in the trophozoites?
P. ovale or vivax
Enlarged red cells in the schizont phase?
P. vivax
Key characteristic of why falciparum is so bad:
able to infect red cells of any age
Red cell pathology from P. falciparum infx: (4 of them)
- rosettes-caused by infected cell binding normal RBCs
- abnormal RBC binding to epithilium
- blood flow impedance
- main cause of death in children: cerebral ischemia
What’s a PFEMP?
knob on outside of infected RBC that binds vascular endothelial cells
Clinical sx of falciparum infx?
Splenomegaly
- parasites in RBCs
- super-active macrophages
- if chronic: fibrosis, grayish color
Liver enlarged and pigmented
Brain vessels get plugged:
- red cell rosettes
- perivascular hypoxia
- ischemia
Heart and lungs may also be involved
Incubation period?
1-2 weeks
Prodrome sx?
Flu-like
Fever comes and goes how often with each bug?
falciparum:
vivax/ovale:
malariae:
Quotidian (daily)
Tertian (every 48 hours)
Quartan (every 72 hours)
Host resistance occurs in?
hemoglobinopathies
ie: sickle cell, G6PD def, thalassemias, ABO antigens
How does falciparum evade partial host immune mediated resistance in endemic areas?
antigenic variation of PFEMS (the little bumps)
Gold standard for dx:
blood smear
other dx basis:
clinical sx + hx (travel, contact with infected blood)
rapid immunochromatographic tests
