A paradigm change
It was always believed that resistance is provoked by antimalarial drugs; they cause plasmodium to evolve and become tougher. Consequently it was important to kill the last parasite to avoid recrudescence. But Andrew Read (Conference Evolution, Utah, June 21-25 2013) finds that in a weakened immune system parasites multiply to extremely high densities. This pool of parasites contains a larger number of mutants, upping the chances of some having greater virulence potential.