Malaria Flashcards
How common are P. vivax infections?
~45% of malaria cases
Explain the difference between short-prepatent & long-prepatent sporozoites & how one of these is related to replapse. ( P. vivax)
short prepatent: invade heptocytes develop into metzoites leave hepatocytes & invade RBCs
long prepatent: invade heptocytes develop into metozoites remain in heptocytes = hypnozoites
relapse bc hypnozoites leave liver & invade RBCs
Where are Duffy antigens found & why are they significant in P. vivax infection? ( P. vivax)
surface of RBCs
merozoites can only penetrate RBCs with Duffy antigen on surface
What people are resistant to vivax malaria?
Duffy negative
What are Schnuffner’s dots?
stipplies on RBCs in P. vivax
How often do the fevers occur in P. vivax infection?
every 48 hours
How common are P. malariae infections?
~7% of cases
How often do the fevers occur in P. malariae infection?
every 72 hours
What is the band form in P. malariae?
mature ring stage
elongates and bnad forms
How does recrudescence differ from relapse? (P. malariae)
sick, recover, sick again
bc of sudden increase in persistant undetected population in blood
can never donate blood again
How common are P. ovale infections?
rare
How often to the fevers occur in P. ovale?
mild fevers every 48 hrs
How did the parasite get its name? (P. ovale)
Mature schizout and RBC are oval shaped
How common are P. falciparum infections?
> 50% of all malaria cases
What symptoms occur in cerebral malaria?
heaches coma high fever (108 degrees F) convulsions fatal within 24-72 hrs
How does the mechanical hypothesis explain cerebral malaria?
bind to endothelial cells
block capillaries
reduce blood flow
hypoxia
How does the humoral hypothesis explain cerebral malaria?
malarial toin stimulates macrophages to release cytokines
stimulate production of nitric oxide
diffuses across BBB & effect synaptic function
similar to general anesthetics & high ethanol concentration
What happens in Blackwater fever?
acute massive lysis of RBCs infected & uninfected high levels of Hb & hemozoin in blood urine very dark kidney failure autoimmune
Why is there a difference in pathology between P. falciparum & the other human Plasmodium species?
P.v. = young RBCs R.m. = old RBCs P.o. = young RBCs P.f. = all
How does sickle cell Hb differ from normal Hb?
B chains have one glutamic acid replaced by valine
What happens to sickle cell Hb during oxygen stress?
sickle shape
reduce flexibility
What is the heterozygote advantage and what can happen to homozygotes?
~60% RBC - normal Hb
~40% RBC - sickle Hb
level of parasitemia is 1%
homozygotes die young from Plasmodium f. infection
How does quinine function?
acts on blood stages
How does chloroquine function?
blocks heme polymerase
against blood stages
How does pyrimethamine function?
against liver stage
inhibits dihydrofolate reductase necessary for folic acid synthesis
What adverse events are associated with mefloquine?
adverse CNS effects -
depression, anxiety, paranoia, aggression, seizures, birth defects
What drugs are found in ACTs?
Artmenisimin based combination therapies
- one drug is derivate of artemisinin related to Artmenisia annina (plant)
- partner drug used in combination (ex: Mefloquine)
The derivative of artmenisinin is based on what compound?
Artmenisia annina (plant)
How do the derivative & the partner drug differ in ACTs? Why is this difference significant?
The partner drugs use different modes of action to wipeout parasite. THis prevents the development of resistance to the drugs.
What is premunition?
resistance to super infection
What are children so susceptible to Plasmodium infections?
no longer breastfeeding
immune system is not fully developed
What does the RTS,S vaccine stimulate and how does this affect the parasite?
stimulates antibody production & T cell response
parasite doesn’t develop in the liver
Where was the PfSPZ vaccine developed?
Rockville, MD
How is the PfSPZ vaccine produced?
weakened form of sporozoite from salivary glands of irradiated mosquitos are harvested
How can mosquitos be controlled?
destruction of breeding sites
mosquito predators
insecticides
bed nets
