Risk to U.S. Travelers
It is important that people who intend to travel to areas where malaria is endemic talk to their healthcare provider about malaria protection before they travel. Their risk of exposure to malaria can be evaluated and proper precautions taken before, during, and after their trip. Even people who have had malaria previously can become reinfected. Similarly, people who originally come from endemic areas are at risk when they return for a visit.
For travelers, the risk of contracting malaria depends on the time of year, the country or countries visited, including specific areas visited within a country, the length of visit, and the type of activities. For example, a traveler to West Africa who will be backpacking and sleeping in tents for several weeks is at greater risk than a traveler who will spend a day or two in a country with relatively low malaria frequency and stay in a hotel with closed windows and air conditioning. According to the Centers for Disease Control and Prevention (CDC), the parts of the world with highest estimated relative risk of infection to U.S. travelers are West Africa and the tropical islands of the Pacific.
For details, see the CDC web page on Malaria Risk Information and Prophylaxis, by Country.