Malaria
Malaria is a Plasmodium infection acquired from Anopheles mosquito bites, most often diagnosed in returning travelers from sub-Saharan Africa, and severe Plasmodium falciparum disease is a medical emergency treated with IV artesunate.
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What this article covers
- Overview
Mosquito-borne protozoal infection: malaria is caused by Plasmodium parasites transmitted by the bite of an infected Anopheles mosquito; the parasite first matures in the liver and then infects erythrocytes.
- Epidemiology
Species-specific geography: P. vivax is tropical/temperate; P.
- Risk factors
Travel to or residence in an endemic area without effective chemoprophylaxis: the dominant risk factor; risk is highest in sub-Saharan Africa.
- Pathophysiology
Inoculation and hepatic maturation: sporozoites are injected by an infected Anopheles mosquito and travel to the liver, where the parasite matures before release into the bloodstream.
- Clinical features
Fever with paroxysmal pattern: classically every 48 or 72 hours depending on species, though fever may be continuous or irregular with P.
- Differential diagnosis
Incubation period narrows fever in a returned traveler: onset within 2 weeks of exposure fits dengue (4 to 7 days), Zika (3 to 14 days), or typhoid (1 to 2 weeks); hepatitis A (2 to 6 weeks) and…
- Diagnosis
Diagnosis is established by identifying malarial parasites on the peripheral blood smear, which is diagnostic; Giemsa-stained thick and thin smears are examined, and morphologic features on the smear help determine the infecting species.
- Management
First, determine the infecting species, the likely region of drug resistance, and whether severity criteria are met, because chemoprophylaxis and treatment both depend on possible drug resistance and individual contraindications.
- Complications
Cerebral malaria and multiorgan failure: mental status alterations, seizures, hepatic failure, disseminated intravascular coagulation, and shock in severe P.
- Prognosis
Species is the dominant prognostic factor: severe disease and death occur primarily with P.
- Prevention
Personal protective measures: limit outdoor exposure between dusk and dawn, use insecticide-impregnated bed nets, and use insect repellents containing 20% DEET.
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