MALARIA DIVERSITY IN THE SAHELO-SAHARAN REGION - A REVIEW OF THE SITUATION IN NIGER, WEST AFRICA

The concept of epidemiologic facies of malaria underlines the diversity in the expression of the disease in areas where important ecological variations interfere largely with transmission. Niger is quite a border region between the afrotropical fauna from the south and the palearctic fauna from the north. The last one filters through the mountains where it maybe represents a relict of ancient paleoclimates. Annual variations of the northern limit of Anopheles arabiensis, in the sahelo-saharian region including some oases, are related to temporary breeding places produced by seasonal rainfall, after estivation during the dry season or after a long migration with the wind. An. gambiae s.s is present in the south and along the Niger river, with An. funestus, even till Zinder. The northern limit of An. nili is the Niger river. The permanent variations of the environment induce great differences in the level of transmission between an intermediate stable situation in the south to an unstable one in the north. Epidemic outbreaks appear some years in vulnerable populations, The implementation of a malaria program supposes to take account of the various eco-epidemiologic situations all over the country. Even if mortality and morbidity became lower, natural premunition of some groups of people must be preserved.