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Abstract Background Resistance of Plasmodium falciparum to anti-malarial drugs has hampered efforts to eradicate malaria. Recent reports of a decline in the prevalence of chloroquine-resistant P. falciparum in several countries, including Malawi and Zambia, is raising the hope of reintroducing chloroquine in the near future, ideally in combination with another anti-malarial drug for the treatment of uncomplicated malaria. In Côte d’Ivoire, the decrease in the clinical efficacy of chloroquine, in addition to a high proportion of clinical isolates carrying the Thr-76 mutant allele of the pfcrt gene, had led to the discontinuation of the use of chloroquine in 2004. Previous studies have indicated the persistence of a high prevalence of the Thr-76 mutant allele despite the withdrawal of chloroquine as first-line anti-malarial drug. This present study is conducted to determine the prevalence of the Thr-76T mutant allele of the Pfcrt gene after a decade of the ban on the sale and use of chloroquine in Côte d’Ivoire. Results Analysis of the 64 sequences from all three study sites indicated a prevalence of 15% (10/64) of the Thr-76 mutant allele against 62% (40/64) of the Lys-76 wild-type allele. No mutation of the allele Thr-76 was observed at Anonkoua Kouté while this mutant allele was in 31% (5/16) and 25% (5/20) of isolate sequences from Port-Bouët and Ayamé respectively. Conclusion More than a decade after the discontinuation of the use of chloroquine in Côte d’Ivoire, the proportion of parasites sensitive to this anti-malarial seems to increase in Anonkoua-kouté, Port-bouët and Ayamé.

Artemisinin-resistant malaria has not been reported from Africa, but resistance can possibly spread from Asia or arise independently in Africa. The emergence of artemisinin resistance in Africa can be monitored by molecular assay of Kelch 13 (K13) propeller sequences. A total of 251 archived DNA samples of Plasmodium falciparum isolates collected in 2002, 2003, and 2006 in Yaounde, Cameroon, and 47 samples collected in 2006 and 2013 in Abidjan, Côte d'Ivoire, were analyzed for K13-propeller sequence polymorphism. Only one isolate carried a mutant K13-propeller allele (E602D). None of the isolates carried the key mutant alleles (Y493H, R539T, I543T, and C580Y) associated with artemisinin resistance in Cambodia. The presence of the mutant allele was not correlated with in vitro response to dihydroartemisinin determined by the classical hypoxanthine incorporation assay. There was no evidence of K13 mutations associated with artemisinin resistance before and soon after the introduction of artemisinin-based combination therapies in Cameroon and Côte d'Ivoire.