The prevention of relapses in malaria remains largely an unsolved problem despite the development of new and more potent antimalarial drugs. The probability of radical cure in an individual, or of cures in a group, Sapero1 believes is determined by the factor of drug efficacy plus the factor of host immunity. The net effect of these is reduced or augmented by a third factor, the inherent characteristics of the species or strains of malaria concerned. Thus the attainment of radical cure either in an individual or the percentage of such cures in any group is not solely a matter of exact therapeutic method, as is commonly believed.
The variability of immune response is demonstrated by the fact that some persons who acquire malarial infection may experience complete cure without the benefit of drug therapy. while others fail to attain a radical cure despite the curative effects of both treatment