Effects of drug pressure and human migration on antimalarial resistance in circulating Plasmodium falciparum malaria parasites in Ecuador.

Antimalarial resistance in Plasmodium falciparum is a public health problem in the fight against malaria in Ecuador. Characterizing the molecular epidemiology of drug resistance genes helps to understand the emergence and spread of resistant parasites. In this study, the effects of drug pressure and human migration on antimalarial resistance in P. falciparum were evaluated. Sixty-seven samples from northwestern Ecuador from the 2019-2021 period were analyzed. SNPs in Pfcrt , Pfdhps , Pfdhfr , Pfmdr-1 , Pfk13 and Pfaat1 were identified by Sanger sequencing and whole-genome sequencing. A comparison of the frequencies of the haplotypes was made with data from the 2013-2015 period. Also, nucleotide and haplotype diversity were calculated. The frequencies of the mutant haplotypes, CVM ET in Pfcrt and C I C N I in Pfdhfr , increased. NED F S D F Y in Pfmdr-1 was detected for the first time. While the wild-type haplotypes, SAKAA in Pfdhps and MYRIC in Pfk13 , remained dominant. Interestingly, the A16 V mutation in Pfdhfr that gives resistance to proguanil is reported in Ecuador. In conclusion, parasites resistant to chloroquine ( Pfcrt ) and pyrimethamine ( Pfdhfr ) increased in recent years, while parasites sensitive to sulfadoxine ( Pfdhps ) and artemisinin ( Pfk13 ) prevail in Ecuador. Therefore, the current treatment is still useful against P. falciparum . The frequent human migration between Ecuador and Colombia has likely contributed to the spread of resistant parasites. Keys words : Plasmodium falciparum , resistance, antimalarial, selective pressure, human migration.