[Drug resistance of Plasmodium falciparum. Analysis of factors in its appearance and spread].

After recalling the biochemical and genetic mechanisms of P. falciparum chemo-resistance, the authors report on an analytic study of the factors ruling the apparition and diffusion of resistant strains. The phenomenon is of chromosomic origin. The repetitive and high doses of drugs exert a pressure on the strains which is the main factor for revealing the selecting resistant mutants. Other facilitating factors may operate such as a lack of immunity of the considered population, a possible particular efficiency of some anopheles (more specially A. balabacencis) in the transmission of chloroquino-resistant strains, transfers of population acting either by a massive arrival of persons receptive or carrying resistant plasmodia. The most serious concern is the recent apparition of polyresistant cases in the Indochina Peninsula. The geographical distribution of chloroquino-resistance suggests the existence of two distinct stocks of P. falciparum: one indigenous to Africa and the Atlantic skirt of the American continent, the other to south-est Asia and deep tropical America. Prophylactif consequences, though difficult to apply, are proposed.