Malaria

Malaria parasites have been with us since the dawn of time. They probably originated in Africa (along with mankind) and fossils of mosquitoes up to 30 million years old show that the vector for malaria was present well before the earliest history. The Plasmodium parasites are highly specific, with man as the only vertebrate host and Anopheles mosquitoes as the vectors. This specificity of the parasites also points towards a long and adaptive relationship with our species.

At present, at least 300,000,000 people are affected by malaria globally, and there are between 1,000,000 and 1,500,000 malaria deaths per year . Malaria is generally endemic in the tropics, with extensions into the subtropics. Malaria in travellers arriving by air is now an important cause of death in non malarious areas, and this is not helped by the common ignorance or indifference of travellers to prophylaxis. Distribution varies greatly from country to country, and within the counties themselves, as the flight range of the vector from a suitable habitat is fortunately limited to a maximum of 2 miles, not taking account of prevailing wind etc. The map indicates current distribution of indigenous malaria according to the World Health Organization:

In 1990, 80% of cases were in Africa, with the remainder clustered in nine countries: India, Brazil, Afghanistan, Sri-Lanka, Thailand, Indonesia, Vietnam, Cambodia and China. Current data for Africa is unavailable. The disease is endemic in 91 countries currently, with small pockets of transmission in a further eight. Plasmodium falciparum is the predominant species, with 120,000,000 new cases and up to 1,000,000 deaths per year globally. It is the Plasmodium falciparum species which has given rise to the formidable drug resistant strains emerging in Asia.

Adapted from a page on Malaria, 1996.

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