Every year 300-500 million people suffer from this disease. It is found in some 90 countries in Africa, Asia, Oceania and South America and in the islands on Hispaniola in the Caribbean. Malaria in man is caused by 4 distinct species of malaria parasite - Plasmodium vivax Plasmodium falciparum Plasmodium malariae Plasmodium ovale Plasmodium vivax has the widest geographic distribution throughout the world and causes much debilitating disease. P. falciparum is also wide spread, results in the most severe infections and is responsible for nearly all malaria-related deaths. P. ovale is very rare parasite of man, mostly confined to tropical Africa .
Malaria is spread by the bite of the female anopheles mosquito.
Malaria is often seasonal coinciding with the rainy season which provides water for mosquito breeding and increased humidity favoring mosquito survival. These gametocytes develop in the body of the mosquito and form sporozoites. The sporozoites fill the salivary glands of the mosquito. For transmission of malaria, the mosquito must live for at least 10 days after an infective blood meal during which it must bite a susceptible host. Rarely malaria can spread by inoculation of blood from an infected person to a healthy person if care is not taken during blood transfusion and during pregnancy from the mother to the growing fetus.