Antimalarial Drug Resistance

Malaria is a hematoprotozoan parasitic infection transmitted by certain species of anopheline mosquitoes. Four species of Plasmodium commonly infect humans, but Plasmodium falciparum, accounts for the majority of instances of morbidity and mortality. There has been a resurgence of interest in malaria in recent years because the efforts at control have foundered after the failure of the global eradication campaign in the 1960s. The control of malaria depends on two strong arms: the first is control of the anopheline mosquito vector through removal of breeding sites, use of insecticides and prevention of contact with humans via the use of screens and insecticide impregnated bed nets and the second is effective case management. A long hoped third arm, an effective malaria vaccine, has not materialized and is not expected for another decade. The antimalarials used in case management has largely relied on chloroquine, and sulfadoxinepyrimethamine [SP], which are inexpensive and widely available and are eliminated slowly from the body. Antimalarials are among the most commonly used medications in tropical areas of the world and its misuse is also widespread. In many parts of the tropics, the majority of the population has detectable concentrations of chloroquine in the blood. The extensive deployment of these antimalarial drugs, in the past fifty years, has provided a tremendous selection pressure on human malaria parasites to evolve mechanisms of resistance. The emergence of resistance, particularly in P. falciparum, has been a major contributor to the global resurgence of malaria in the last three decades and it is the most likely explanation for a doubling of malariaattributable child mortality in eastern and southern Africa.