In vitro susceptibility of Plasmodium falciparum to monodesethylamodiaquine, quinine, mefloquine and halofantrine in Abidjan (Cote d'Ivoire)

Background: Malaria is the primary cause of hospitalization in Cote d'Ivoire. Early treatment is one of the strategies to control this illness. However, the spread of resistance of Plasmodium falciparum to antimalarial drugs can seriously compromise this strategy. Objectives: The aim of this study was to assess the in vitro susceptibility of P. falciparum to monodesethylamodiaquine and aminoalcohols in Abidjan (Cote d'Ivoire). Methods: We assessed the in vitro susceptibility of isolates collected from patients with uncomplicated malaria by using the WHO optical microtest technique. Results: The proportions of resistance to monodesethylamodiaquine, mefloquine and halofantrine were 12.5%, 15.6% and 25.9%, respectively. For quinine, none of isolates showed evidence of in vitro resistance. However, two isolates (6.1%) had IC(50) values above 300 nM. The IC(50) of each drug was positively and significantly correlated to that of the other three drugs, and the correlation was higher between halofantrine and mefloquine. Conclusions: Our results showed that the in vitro chloroquine resistance reported in previous studies has been extended to other antimalarial drugs investigated in this study except for quinine. Therefore, it is necessary to implement a long-term monitoring system of antimalarial drug resistance.