Prevalence of the K76T mutation in the putative Plasmodium falciparum chloroquine resistance transporter (pfcrt) gene and its relation to chloroquineresistance in Mozambique

K76T, a mutation in the Plasmodium falciparum chloroquine (CQ) resistance t ransporter protein, has been implicated in resistance to CQ. A modified 14- day in vivo test to estimate the CQ resistance level was done in southern M ozambique: 21 (42%) of 50 subjects who completed the follow-up were CQ susc eptible. Use of msa2-restriction fragment length polymorphism (RFLP) genoty ping to differentiate new from recrudescent infections made little differen ce in the estimated prevalence of resistance. The K76T mutation prevalence was estimated by RFLP-polymerase chain reaction and sequencing, and its rel ation to parasitological CQ resistance was explored on day 0 samples: 51 of 56 pretreatment samples presented the T76 codon, and it was present in 100 % of children with parasitological resistance. T76 also was present in 18 o f 23 subjects in whom the infection resolved after CQ treatment. These find ings show a high prevalence of the K76T mutation among wild isolates but al so suggest additional factors responsible for CQ resistance.