Malaria remains a life-threatening parasitic infection endemic throughout much of the world. It is estimated that in 2010 there were 216 million infections and 655 000 deaths due to malaria, with the majority of deaths among African children. In nonendemic countries, it is one of the most common causes of fever in returned travelers and recent immigrants, and several thousand people with malaria arrive in nonendemic countries yearly.

Malaria is a mosquito-borne protozoal infection caused by one of four human Plasmodium species (Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, and Plasmodium malariae), or with the monkey parasite, Plasmodium knowlesi, which has been increasingly described in parts of Southeast Asia. Malaria endemic countries are shown in Figure 200.1. Given the risk of rapid progression to severe disease in nonimmune individuals, a high index of suspicion is critical when evaluating patients with febrile illness following travel to malarious areas, especially those endemic for P. falciparum. Proper treatment of malaria requires knowledge of the infecting species and where it was acquired, since drug resistance patterns vary geographically. Widespread chloroquine-resistant P. falciparum (CRPF) malaria and emergence of resistance to other drugs have complicated treatment and prophylaxis.

CLINICAL ASPECTS

Fever in a patient who has recently traveled to an area endemic for malaria should be considered a medical emergency. The minimum incubation period is generally considered to be 7 days after inoculation, and of greatest concern is the patient who has traveled to a P. falciparum endemic area within 2 months of presentation, since an incubation period of 2 to 4 weeks is typical for falciparum malaria.