Micro: Vector Borne Inf 2 - Malaria Flashcards
What are the areas of chloroquine resistant P. falciparum?
ALL of sub-saharan Africa
basically everywhere EXCEPT Haiti and central America north of Panama canal
What is the infectious form of malaria?
sporozoite - goes to liver and undergoes schizogony before young trophozoite stages enter bloodstream and infect erythrocytes
What are the developmental stages of malaria apparent in peripheral blood?
rings - early, asexual stage in erythrocytes
trophozoites - asexual, larger and less ring shaped, start to accumulate malarial pigment
schizonts - asexual, begun dividing into merozoites w chromatin
gametocytes - sexual, necessary for inf of mosquitos where further sexual dev happens
What are the different appearances of trophozoites for different species of malaria?
p. vivax - ameboid, larger erythrocytes affected, contain pink dots = Schuffners dots
p. ovale - oval, teardrop, elongated erythrocytes, pulled out fimbriated cell membranes, James’s dots
Which malaria species affect the liver differently and how?
p. vivax and p. ovale have hypnozoite resting forms in liver than can later mature and cause relapse
need to treat peripheral blood stages AND primaquine for liver forms
How is malaria diagnosed?
thick blood film - RBCs lysed, more sensitive b/c larger volume, giemsa stains, pH of 7.2-7.4 or no dots
thin blood film - can differentiate species, p. falciparum may have small dark slits = Maurer’s clefts
EIA, PCR and Ab tests in some labs
After merozoites invade RBCs, what is the pathogenesis of malaria?
feed on hemoglobin and mature into trophozoites - undergo nuclear division to form 16-32 schizonts per RBC - RBC ruptures and schizonts release merozoites that infect new RBCs
What are the clinical manifestations of malaria?
*fever, may be cyclical, ab discomfort, cough, SOB, jaundice, renal failure, altered consciousness (cerebral malaria), seizures (cerebral malaria, hypoglycemia)
anemia, hepatosplenomegaly
hypoglycemia and lactic acidosis w p. falciparum
What is the prophylaxis for malaria in travelers?
chloroquine if area not resistant
if resistant: mefloquine (childrens dose depends on weight), doxy (NOT for pregnant or lactating), malarone (not for small children, pregnant or lactating), primaquine (NOT for pregnancy or G6PD def), tafenoquine (experimental)
What is the treatment for malaria?
chloroquine phosphate (PO) or sulfate (IV/IM) for uncomplicated (i.e. not falciparum) chloroquine resistant p. vivax - atovaquone-proguanil = malarone chloroquine resistant falciparum - quinine sulfate + doxy + pyrimethamine-sulfadoxine, or + clinda (or mefloquine, malarone, or mefloquine + doxy)
What is recrudescence?
controllable number of parasites remain in bloodstream latent in RBCs due to inadequate immune response or antimalarial therapy
reactivate upon physical trauma or immunosuppression
What causes the cerebral malaria and kidney failure seen w p. falciparum?
inf RBCs produce knobs on surface - sticky and bind to endothelial cell lining of microvasculature in brain, kidney, lung, other organs
leads to aggregation or rosetting of uninfected RBCs = sequestration - clogs up capillary microvasculature in CNS and kidneys