November 29, 2015
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Travel Medicine (cont.)

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Malaria is an infection caused by a protozoan that enters red blood cells and multiplies until the cells burst open. The broken cells release the young protozoa into the bloodstream where they infect more red blood cells. This release of young protozoa causes high fevers that can last for several hours, as well as anemia due to the destruction of red cells. The fever of malaria often comes and goes, coinciding with when the infected red cells burst open. With some types of malaria, the protozoa can hide in the liver and cause episodes of fever over many years. In serious cases, malaria can cause the kidneys to shut down, can infect the brain (cerebral malaria), or cause death.

Malaria is spread to people by mosquitoes. The mosquitoes bite between dusk and dawn. Malaria occurs in many tropical areas and a few areas that have a milder climate. Travelers to sub-Saharan Africa, South America, and Asia may be at risk for the disease. Some countries in Central America and the Caribbean also have malaria. Not every area of a country will be affected. The people who have lived all their lives in the area with malaria typically have some immunity, but travelers are at much higher risk for severe infection, especially with some types of malaria. Malaria is serious enough to see a doctor about possible preventive medication if your itinerary suggests you might be exposed. The CDC has a web page that tells where malaria occurs ( Many public-health departments and some private travel clinics provide pre-travel evaluations. CDC also offers a "Find a Clinic" web page to help you find one ( The American Society for Tropical Medicine and Hygiene also has a list of clinics that specialize in travel medicine ( should visit these clinics at least four to six weeks before you travel in case you need vaccines, but especially with malaria it is better to go later than not at all to avoid traveling unprotected.

Malaria can be prevented by avoiding mosquito bites (see "What can I do to avoid insect bites?") and by taking preventive medications. Travelers who will be exposed to malaria should take medications starting before travel to the area and continuing for a time after they leave the area. Several different medicines are available. Some are taken only once a week, and others are taken daily. In some countries, malaria has become resistant to older medicines. Your physician or travel clinic will choose which medicine to use based on what countries you are visiting. Some medicines must be started two weeks before departure, so you should plan to go to the doctor or travel clinic well in advance. It is very important to take every last dose of preventive medication that may be prescribed to take after you return home, especially with types of malaria that hide in the liver and can return months later.

Medically Reviewed by a Doctor on 8/19/2015


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