Drug resistance in malaria—A perspective

Abstract

One of the major technical problems facing malaria eradication in certain areas is the development of drug resistance. Resistance presents difficulties mainly in relation to P. falciparum infection. Proguanil and pyrimethamine resistance have seldom been reported in other species in the field and chloroquine resistance so far is restricted to P. falciparum malaria. The distribution of chloroquine resistance and multiple resistance in P. falciparum in South America and South-east Asia is reviewed and figured in two maps. The history of the development of resistance is discussed. The main predisposing conditions to resistance appear to be the influx of people with low levels of immunity into an area of continuing transmission, the presence there of resistant mutant parasites and free availability of the respective antimalarials. It is suggested that the underlying mechanisms by which resistant strains emerge are essentially the same for chloroquine as for folic reductase inhibitors. It is suggested moreover that chloroquine resistance may emerge in time in Africa where, until now, no proved foci of such strains have been recorded. The main weapon against drug resistance is the interruption of malaria transmission by residual spraying but in certain problem areas this is not possible. In these areas little can be done when multiple-resistant parasites are present until better drugs are available. A brief reference is made to the treatment of chloroquine-resistant P. falciparum malaria.