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Key Features

Essentials of Diagnosis

  • Residence in or travel to an endemic area (fever in the returning traveler)

  • Cyclic paroxysms of fever, chills, and intense sweating

  • Headache, backache, cough, abdominal pain, nausea, vomiting, diarrhea

  • Splenomegaly, anemia

  • Can progress to coma, seizures

  • Malaria parasites in peripheral blood smear

General Considerations

  • Human malaria is caused by five Plasmodium species

    • Plasmodium vivax (most common)

    • Plasmodium falciparum (most virulent)

    • Plasmodium ovale (similar to P vivax)

    • Plasmodium malariae

    • Plasmodium knowlesi (a primate parasite recognized as a cause of malaria in humans)

  • The female Anopheles mosquito transmits the parasites

  • In early stages of infection, asynchronous erythrocytic cycles of hemolysis commonly cause daily fevers

  • Eventually, synchronous erythrocytic cycles begin as parasites rupture the infected cells at more regular 48- or 72-hour intervals

  • Survival is associated with a progressive decrease in intensity of cycles

  • Relapses years later may occur from persistent hepatic infection, which occurs in P vivax and P ovale infections


  • Causes approximately 1 million deaths each year, over 80% of which occur in children younger than 5 years of age in sub-Saharan Africa

  • Global efforts toward prevention and treatment have led to declining mortality and morbidity

  • Approximately 1500 imported cases are diagnosed in the United States each year; local transmission may occasionally take place from imported cases

Clinical Findings

Symptoms and Signs

  • Fever and vomiting are the most common presenting symptoms in children

  • Common presenting symptoms in infants

    • Recurrent fever

    • Irritability

    • Poor feeding

    • Vomiting

    • Jaundice

    • Splenomegaly

  • Rash is usually absent

  • Classic symptoms in older children

    • Fever with chills

    • Rigors

    • Headache

    • Backache

    • Myalgia

    • Fatigue

  • Signs of severe malaria in children include

    • Altered mental status

    • Seizures

    • Respiratory distress

    • Hypoglycemia

    • Acidosis

    • Parasitemia > 5%

  • Fever may be cyclic (every 48 hours for all but P malariae infection, in which it occurs every 72 hours) or irregular (most commonly observed with P falciparum)

  • Infection during pregnancy often causes intrauterine growth restriction or premature delivery but rarely true fetal infection

  • Physical examination in patients with uncomplicated cases may show only mild splenomegaly and anemia

Differential Diagnosis

  • Clinical features may not reliably distinguish malaria from other infections in children, so a high index of suspicion in patients with exposure in endemic areas is necessary

  • Differential diagnosis of fever in a returning traveler should be based on diseases endemic to the region of travel and may include

    • Typhoid fever

    • Tuberculosis

    • Rickettsial disease

    • Brucellosis

    • Leptospirosis

    • Yellow fever

    • Dengue fever

    • Chikungunya

    • Borreliosis

  • However, other common causes of fever, such as influenza, Mycoplasma pneumoniae or enteroviral infection, and serious bacterial causes such as occult sinusitis, meningitis, pneumonia, or bacteremia should be considered

  • Malaria may also coexist with other diseases


  • One or more of the five ...

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