Mapping the Spread of Malaria Drug Resistance

Drug resistance is a recurrent theme in the history of infectious disease control. In the case of malaria, resistance to all but one of the five major classes of drugs is widespread [1]. Such resistance occurs because of the strong selection pressure associated with giving patients antimalarial drugs. The most effective way to stall resistance would therefore be to eliminate selection by halting drug treatment [2], but this is rarely a feasible option. Hence alternative approaches to managing resistance are needed. First of all, we need to better understand the manner in which resistance evolves and spreads within populations. Molecular methods provide the tools needed for investigating the evolution and the spread of resistance genes. These methods can be used to answer a multitude of pertinent questions: Do resistance alleles have few or many origins? Do they spread locally or globally? Do parasites form a single pan-African population, or are there barriers to gene flow? In turn, the answers to these questions can be used to make rational decisions about drug treatment policy.