0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:16
942 MalariaMALARIA
SARAH STAEDKE, MD
history & physical
History
■Malaria is caused by one (or more) of the plasmodial species that
infect humans: P. falciparum, P. vivax, P. ovale, and P. malariae. P.
knowlesi, an agent of malaria in monkeys, has been recently shown
to cause human disease.
■P. falciparum causes >90% of all deaths.
■Malaria is primarily transmitted by infected female anopheles
mosquitoes that bite from dusk to dawn.
■Other modes of transmission: blood transfusion, needlestick injury,
IVDA, organ transplantation, congenital
■Risk factors: non-immune host (children <5 years); pregnant women;
travel to endemic region; mosquito exposure; chemoprophylaxis and
compliance. P. knowlesi associated with travel to forested tropical
regions with infected monkeys.
■Drug resistance (particularly P. falciparum) is a major problem.
■Important features of P. falciparum: infects RBCs of all ages, produc-
ing high-level parasitemia; infected RBCs adhere to endothelial cells
and sequester in peripheral vasculature, contributing to microvas-
cular disease
■P. vivax and P. ovale form dormant intrahepatic hypnozoites, which
may produce relapses years after initial infection and require specific
therapy.
■Complete immunity does not develop after infection; semi-
immunity develops after years of exposure but wanes in the absence
of exposure to malaria parasites.Signs & Symptoms
■Incubation period usually 7–21 days; onset may be delayed for years
■Fever is primary symptom; classic malaria paroxysm=chills, high
fever, and sweating; cyclical fevers occur only in well-established
infections, and fever pattern is usually not helpful; tertian – fever
every 48 h=P. vivax and P. ovale; irregular tertian=P. falciparum;
quartan – fever every 72 h=P. malariae
■Other symptoms: headache, malaise, backache, arthralgias, myal-
gias, nausea and vomiting, abdominal pain, diarrhea, cough
■Signs: pallor, jaundice, splenomegaly; no rash