B3-090 Protozoal Infections Flashcards
main species causing 95% of malaria
plasmodium faciparum
plasmodium vivax
a majority of malaria in the US comes from
imported from visiting friends and relatives
risk factors for malaria
living in an endemic area
why are VFRs the highest risk causing malaria?
travel to more rural areas
poor adherence to propyhlaxis
how is malaria most often transmitted?
anopheles mosquito bite
less common transmissions of malara
blood transfusion
transplacental
needlestick
incubation time of malaria
2 ish weeks
which strains of malaria become hypnozoities and remain in the liver?
P. ovale
P. vivax
sporozoites penetrate the hepatocyte via attachment of the sporozoitie surface protein coat to the hepatocyte heparan sulfate glycoproteins and LDL receptor
malaria
diagnosis is really in thinking about it and having a low threshold of suspicion
malaria
clinical presentation of malaria
fever, chills, headache, splenomegaly
**almost any symptom has been reported.
3 stages of malarial paroxysm
- cold or chilling stage
- hot stage
- sweating stage
cyclic fevers are a hallmark of ________ caused by ___________
malaria; lysis of RBCs
tertian malaria is caused by what organisms?
P. vivax, P. ovale
Fevers occur every 48 hours
Quartan malaria is caused by what organisms?
P. malariae
fevers occur every 72 hours
P. falciparum causes _________ fevers
continuous
w/ intermittent irregular spikes
**on 48 hour cycle
laboratory findings: malaria
anemia
WBC fluctuation
thrombocytopenia
evidence of hemolysis
Sequestration is caused by __________ and results in ___________
P. faciparum; endothelial margination and stickiness
why is P. falciparum the most virulent strain of malaria?
infects all RBCs
sequestration
cerebral malaria
hypoglycemia
lactic acidosis
severe anemia
pulmonary edema
tropical splenomegaly
blackwater fever
are complications of which malarial organism
P. falciparum
late splenic rupture is a complication of which malarial organism
P. vivax
immune complex glomerulonephritis is a complication of which malarial organism
P. malariae
a parasitemia >5% indicates
severe malaria
risk factors for severe malaria
children 6 months-3 years
children and traveler’s who are not immune
malaria immunity requires
repeated exposure
**wanes with lack of exposure
in endemic areas, children are usually protected from malaria after ________ years
three
gold standard for diagnosis of malaria
parasites in RBC on peripheral blood smear
what kind of stain do you use to visualize malaria parasites in RBCs?
Giemsa stain
disadvantage: giema stain
requires expertise and can’t be done STAT
patient deteriorate rapidly
antigen detection has _________ sensitivity for non-falciparum species
decreased
**always back up with smear
a PCR test can be performed for suspected malaria but
not commercially available, and not run STAT
the thick portion of a peripheral blood smear is for
a screening test
**sensitive
the thin portion of a peripheral blood smear is for
species identification and %parisitemia
how should you draw peripheral blood smears for optimal sensitivity?
3 spaced draws over 12-24 hours
a lateral flow assay done for malaria is detecting
HRP-1
con of lateral flow assay for malaria
less sensitive, must be backed up by thick smear
what drug is tissue schizonticidal for malaria?
primaquine
**P. ovale, P. vivax
what drug is the best choice for blood schizonticidal for malaria?
atovaqunone/proguanil
**resistance to chloroquine and mefloquine is growing
if you have clinical suspicion of malaria
perform thick and thin blood smears AND read them within hours (STAT)
if quindine is unavailable, contact CDC malaria hotline for
artesunate
what is malaria related mortality so high?
lack of prevention
diagnostic failure
management failure
“looks like malaria, acts like Lyme disease”
babesia
most common babesia species
B. microti
babesia is usually transmitted by
ixodes tick (NE, MN, WI)
rare routes of transmission for babesia
blood transfusion
transplacental
pathogenesis: malaria and babesia
invade RBCs
cytokine and TNF-a release
fever
causing anemia, thrombocytopenia, splenomegaly
incubation period: babesia
1-4 weeks
may-september seasonality
(75% June-August)
babesia
most babesia infections are
asymptomatic
symptoms of babesia
febrile illness with anemia
shaking, chills, fever, headache, myalgia