Malaria

A serious disease caused by parasitic protozoa called plasmodia. The infection is spread by the bite of anopheles mosquitoes and is prevalent throughout the tropics. Malaria causes severe fever, and, in some cases, fatal complications affecting the kidneys, liver, brain, and blood. There are 4 species of plasmodia that cause malaria:,,, and. When a mosquito carrying any of these species bites a human, the plasmodia enter the bloodstream. They invade the liver and red blood cells, where they multiply. The red cells then rupture, releasing the new parasites. Some of them infect new red cells, and the others develop into forms that can infect more mosquitoes. Falciparum malaria infects more red cells than the other species and therefore causes a more serious infection. Most cases of this form occur in Africa. Symptoms of malaria include fever, shaking, and chills. There may also be severe headache, general malaise, and vomiting. The fever often develops in cycles, occurring every other day (in vivax and ovale infections) or every 3rd day (in malariae infections). Falciparum malaria can be fatal within days. Infected red cells become sticky and block blood vessels in vital organs. The spleen becomes enlarged and the brain may be affected, leading to coma and convulsions. Destruction of blood cells causes haemolytic anaemia (see anaemia, haemolytic). Kidney failure and jaundice often occur. A diagnosis is made by examining a blood sample under a microscope to view the parasites. Chloroquine is the usual treatment for species other than falciparum. Falciparum malaria is treated with quinine, mefloquine, or with proguanil and atovaquone. People with vivax or ovale malaria must also take the drug primaquine. In severe cases, blood transfusions may be needed. Preventive antimalarial drugs should be taken by all visitors to malarial countries. Doctors should be consulted for up-to-date advice on the choice and dosages of drugs to be taken.