Malaria is a parasitic disease caused by four species of Plasmodium protozoa (single-cell parasites): Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae. Of the four species, Plasmodium falciparum is responsible for the most deaths. The parasite transmission by Anopheles mosquitoes, the vector, is affected by climate and geography, and is often highest during the rainy season.
When a malaria-infected Anopheles mosquito bites a human, the parasite passes into the person's bloodstream, where it multiplies and can cause illness or even death. When this person is bitten by another mosquito, the parasite travels from human back to insect and the cycle continues.
Symptoms of malaria include fever, shivering, pain in the joints, headaches, repeated vomiting, convulsions and coma. If left untreated, the disease - particularly that caused by P. falciparum - may progress to severe malaria and sometimes death.
In areas where the disease is endemic, repeated bouts with the disease are common. African children can get malaria many times each year. Such repeated exposure can have grave health consequences: chronic anaemia, malnutrition, retarded physical and cognitive development, and potential increases in vulnerability to other diseases.
Malaria is curable, but so many people in Africa are dying because they are not getting treatment that works.