Malaria Prophylaxis

Excerpt

Malaria is an infection caused by one of five species of Plasmodium and is one of the leading causes of fever in the returning traveler. The Plasmodium species that cause disease in humans are Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi. The infected Anopheles mosquito, most active in the morning and evening, transmits the protozoa to humans. After transmission by an infected mosquito, the Plasmodium sporozoite infects and multiplies within liver cells. These schizonts then get released from liver cells, where they infect red blood cells and again multiply. Clinical disease results from the release of Plasmodium merozoites from the red blood cell. Also, Plasmodium vivax and Plasmodium ovale can remain dormant in the liver (hypnozoites) and can cause disease weeks to years later.

Malaria is endemic to most parts of Africa, South America, East Asia, and parts of Europe and the Middle East. Approximately 125 million visitors travel to these areas, and estimates of malaria infections in travelers range between ten to thirty thousand though the actual number of cases is likely far higher. All travelers to endemic areas should, therefore, receive counseling on areas with a malaria risk, mosquito bite avoidance, and chemoprophylaxis.