World malaria situation 1990. Division of Control of Tropical Diseases. World Health Organization, Geneva.

Malaria risk of varying degree exists in 99 countries or areas. However, falciparum malaria does not exist or its relative prevalence is less than 1% in 13 of these countries. Accurate information on the global incidence of malaria is difficult to obtain because reporting is particularly incomplete in areas known to be highly endemic. The global incidence of malaria is estimated to be nearly 120 million clinical cases each year, with nearly 300 million people carrying the parasite. 90% of the total number of cases reported annually to WHO are from 19 countries only. This does not include the WHO African Region where reporting of cases remains fragmentary and irregular despite improvements in recent years. Some 75% of cases are concentrated in 9 countries (in decreasing order): India, Brazil, Afghanistan, Sri Lanka, Thailand, Indonesia, Viet Nam, Cambodia and China. Furthermore, within these countries malaria is concentrated in certain areas. Of a total world population of about 5.3 billion people, 3.1 billion (59%) live in areas free of malaria (it never existed, disappeared or was eliminated by antimalaria campaigns and the malaria-free status has been maintained). 1.7 billion people (32%) live in areas where endemic malaria was considerably reduced or even eliminated but transmission was reinstated and the situation is unstable or deteriorating. These latter areas include zones with the most severe malaria problems which developed following major ecological or social changes, such as agricultural or other economic exploitation of jungle areas, sociopolitical unrest, etc.; these zones comprise only about 1% of the world population. Areas where endemic malaria remains basically unchanged, and no national antimalaria programme was ever implemented, are inhabited by 500 million people (9%), mainly in tropical Africa. Severe malaria and mortality are caused by Plasmodium falciparum which is the predominant species of malaria in tropical Africa. In the rest of the world it is far less common. WHO receives very limited and irregular reports on malaria deaths. The vast majority of malaria deaths occur in Africa; estimates vary greatly: a figure of 800,000 deaths per year in African children has been quoted in 1991 by the WHO African Region. There are indications that mortality in children has fallen in some areas because of the widespread use of antimalarials, of social development and of better education. Countries in tropical Africa are estimated to have more than 80% of all clinical cases and more than 90% of all parasite carriers.(ABSTRACT TRUNCATED AT 400 WORDS)