Selection of pfmdr1 and pfcrt alleles in amodiaquine treatment failure in north-western Burkina Faso

In 111 children under five years of age and with uncomplicated malaria in Nouna, north-western Burkina Faso, amodiaquine treatment failed in 75% (after PCR-based exclusion of new infections, 32%). In these, we assessed the role of Plasmodium falciparum pfmdr1 and pfcrt polymorphisms in amodiaquine resistance. Except for pfmdr1 1246Y (prevalence, 5%), no P. falciparum allele predicted treatment outcome. Pfcrt 76T as well as pfmdr1 86Y, 86Y-184F-1246D, and 86Y-184Y-1246Y were positively selected in treatment failures, and pfmdr1 86N-184F-1246D negatively. The weak association of pfmdr1/pfcrt alleles with amodiaquine treatment outcome suggests further factors to be involved in the unsatisfactory low efficacy of the drug and limits the usefulness of these markers in this area.