Figure 1

Observed and fitted (by logistic regression) frequencies of pfrt-76 and pfmdr1–86 through time in Kilifi, Kenya and a study in Malawi[3]. Observed (symbols) and predicted (lines) population frequencies through time of alleles pfcrt-76 (top panel) and pfmdr1–86 (bottom panel) involved in resistance to chloroquine in Kenya (solid line, closed symbols) and Malawi (dashed line, open symbols) before and after the official ban on the use of chloroquine (1999 and 1992, respectively). The P-value indicates whether the slope of the predicted line is significantly different from zero. The selection coefficient (s) of the resistant allele relative to the wild-type allele is shown with its 95% confidence intervals for each location.