The in Vitro Assessment of Drug Resistant Malaria in Makurdi, North Central Nigeria

Abstract

Multi-drug resistant malaria parasite strains have spread to new areas that were once free of such strains. This study evaluated the specific in vitro sensitivities of some standard antimalarial drugs, against Plasmodium falciparum isolates in Makurdi, North Central Nigeria. The standard schizonts growth inhibition assays was used to study the in vitro activities of quinine, artesunate, and amodiaquine against 146 isolates in children aged 2-14 years. 100 % of isolates were in vitro sensitive to quinine, geometric mean effective concentration (EC)₅₀ = 241.55 nM, EC₉₀ = 676.08 nM, and EC₉₉ = 993.12 nM; and artesunate, EC₅₀ = 1.05 nM, EC₉₀ = 2.42 nM, and EC₉₉ = 3.16 nM. 1.37 % of isolates were resistant to amodiaquine, EC₅₀ = 22.08 nM, EC₉₀ = 66.22 nM and EC₉₉ = 100.23 nM. Significant in vitro cross resistance was found at EC₅₀ values of quinine-amodiaquine drug pair (r = + 0.342, P < 0.05), but not quinine – artesunate (r = + 0.057, P > 0.05) or artesunateamodiaquine (r = + 0.088, P > 0.05). These results call for constant surveillance, to curb the spread of P. falciparum resistance to amodiaquine in Nigeria.