2: malaria Flashcards
vector for malaria
anopheles freeborni mosquito
what areas of the world do you see malaria?
tropical climates
what map echoes the malaria map?
hemoglobinopathy - tells you selective pressures
describe the plasmodium species that cause disease in humans
5 species:
- falciparum (most severe disease)
- vivax
- ovale
- malariae
- knowlesi
key points of plasmodium lifecycle
- bite of infected mosquito
- plasmodium sporozoites have trophism for hepatocytes
- asexual reproduction in hepatocytes
- release into bloodstream
- hijacking of RBC and degradation of Hb, formation of ring forms
- lyse RBC and release merozoites to invade more RBC, or gametocytes to reinfect mosquitos [hemolytic anemia -> direct hyperbilirubinemia = jaundice]
- P vivax and P ovale can produce dormant hypnozoites in hepatocytes, can reactivate in 3-12 months
host response to malaria
splenic immune reaction and filtrative clearance -> leads to clinical appearance
clinical presentation of malaria:
- general
- what features suggest falciparum over others?
- what features suggest vivax or ovale over others?
- exposure to endemic area
- lack of prophylactic treatment used by travelers
- headache
- fatigue
- myalgias
- abdominal pain
- *fever!
falciparum: seizures
vivax/ovale: paroxysmal chills, fever, rigors (hepatic sequestration and re-release)
physical findings in malaria
- fever
- mild hepatomegaly
- palpable spleen
- mild icterus (jaundice)
-rash is very unusual
why can falciparum cause cerebral malaria?
can cause sequestration and agglutination in vasculature, including CNS capillaries
features of cerebral malaria
- seizures
- encephalopathy
- coma
what causes hypoglycemia in malaria? significance of this sign?
due to decreased hepatic gluconeogenesis and increased systemic glucose utilization - poor prognostic sign
what causes metabolic acidosis in malaria?
due to hypoperfusion, lactic acidemia
what does noncardiogenic pulmonary edema of malaria look like?
ARDS- adult respiratory distress syndrome
what causes renal impairment in malaria?
ATN (acute tubular necrosis)
what hematologic abnormalities do you see in malaria?
anemia
what liver dysfunction do you see in malaria?
- cholestasis
- acute hepatitis
diagnostic testing for malaria: stains
- LM of Giemsa-stained blood smear**
- thick and thin blood smears (to evaluate for ring forms and estimate parasite load)
- thick smears concentrate parasites -> increases diagnostic sensitivity
diagnosis of malaria: lab findings
- nonspecific
- normocytic normochromic anemia w/ evidence of hemolysis (high RDW - tells you size of RBCs)
- increased acute phase reactants (ESR, CRP)
- increased RDW (tells you the variability in size of the RBCs - increases with hemolytic anemia b/c get fragments along with regular red cells)
treatment of malaria - non falciparum
-chloroquine is treatment of choice, if in chloroquine sensitive area
treatment of malaria - falciparum
- if chloroquine sensitive, chloroquine
- if question chloroquine sensitivity, artemisinin-based combos preferred
malaria prevention options
- mosquito tents
- insect repellents
- preventive treatment in travelers (drug choice based on destination)
describe 4 drugs commonly used for malaria prophylaxis
- malarone (atovaquone-proguanil)
- doxycycline
- chloroquine phosphate
- mefloquine HCl
prophylaxis regimen for malarone
- 250 mg atovaquone + 100mg proguanil
- one tablet p.o. daily
- start 1-2d before, through 7d after
- don’t use in pregnancy (insufficient data)
- easy to tolerate, generic, inexpensive
prophylaxis regimen for doxycycline
- 100 mg
- one tablet p.o. daily
- start 102d before, through 4w after
- don’t use in pregnancy (teratogenic)
- used to be inexpensive
prophylaxis regimen for chloroquine phosphate
- 500 mg salt (300 mg base)
- one tablet p.o. weekly
- start 1-2w before, through 4w after
- safe for pregnancy
- generic, inexpensive, easy to tolerate
prophylaxis regimen for mefloquine HCl
- 250 mg salt (228 mg base)
- one tablet p.o. weekly
- start 2-3w before, through 4w after
- safe for pregnancy
- CNS side effects (hypersexual dreams/nightmares)
