Introduction

Malaria is by far the world's most important tropical parasitic disease, and kills more people than any other communicable disease except tuberculosis. In many developing countries, and in Africa especially, malaria exacts an enormous toll in lives, in medical costs, and in days of labour lost. Malaria is a disease caused by protozoa (single - celled parasites) carried by Anopheles mosquitoes. There are four species of malaria parasite. Plasmodium falciparum causes the most severe infections, which can often be fatal. It also accounts for the majority of infections. Plasmodium vivax causes a lower-grade infection that is rarely fatal, but can occur long after the person has left the malaria risk area. Plasmodium ovale and Plasmodium malariae are rarely diagnosed in travellers. Travellers are at higher risk of severe malaria infection, because people living in a malaria region gradually develop a partial degree of immunity. Malaria is a curable disease if promptly diagnosed and adequately treated.