Each year, malaria causes an estimated 500,000 deaths worldwide. Most of these deaths occur in Africa and disproportionally affect children younger than five years worldwide. Human malarial disease is caused by protozoan parasites of the genus Plasmodium. The primary means of infection is through the bite of a female Anopheles mosquito. The incidence of malaria in the United States has increased since 2011, in conjunction with the increase in worldwide travel. An estimated 2,000 cases of malaria occur annually in the United States. All travelers to malaria-endemic regions should be prescribed prophylaxis. Malaria has a broad range of clinical presentations. Travelers who have symptoms of malaria should seek medical attention as soon as possible. All febrile travelers who have recently returned from a malarious area should be evaluated for malaria. The accurate, timely, and species-specific diagnosis of malaria is essential for successful treatment. Direct microscopy of Giemsa-stained blood smears is the reference standard for laboratory diagnosis. Rapid testing for malaria has emerged as an important adjunctive diagnostic modality. Malaria treatment is determined by individual patient factors and geography. The World Health Organization recommends treating uncomplicated cases of malaria with artemisinin combination therapy. [corrected] Severe malaria is mainly caused by Plasmodium falciparum. Children, pregnant patients, and people who are not from endemic regions are at highest risk of severe malaria. Intravenous artesunate is the treatment of choice for severe malaria.