Prevalence and Distribution of Chloroquine Resistance and Susceptible Alleles of Plasmodium falciparum from Selected Primary Health Centers in North-Western Nigeria: Implications for Malaria Treatment

Background: Since the detection of P. falciparum resistant to ACT in western Cambodia, malaria control and elimination efforts have become seriously threatened. The decline in the sensitivity of Plasmodium falciparum to Artemisinin Combination Therapy (ACT) in Nigeria has prompted the unofficial use of chloroquine (CQ) for self-medication. Due to the lost cost and effectiveness of CQ, this study was conducted to evaluate the prevalence and distribution of chloroquine resistance alleles Pfcrt and Pfmdr1 in Plasmodium falciparum isolates from north-western Nigeria to assess the possibility of reintroducing CQ in this region.

Methods: A cross-sectional study was conducted, across five states in north-western Nigeria. After collecting a total of 466 P. falciparum-positive blood samples from various primary health centres in the states. DNA was extracted from these samples and analysed for the presence of mutations in the Pfcrt (K76T) and Pfmdr1 (N86Y) genes using real-time polymerase chain reaction (RT-PCR). The prevalence of these mutations was determined and their distribution was analysed using chi-square, odds ratios, and paired t-tests.

Results: The drug-susceptible Pfmdr1 N86 alleles were the most prevalent, observed in 47.9% of the samples, while the drug-resistant 86Y alleles were found in 28.3%. Also, the Pfcrt K76 alleles, responsible for CQ susceptibility, were present in 17.4% of samples, whereas the 76T alleles, responsible for resistance, were found in 12.4%. Mixed infections (K76T) were the least common at 3.6%. Significant variations were observed in the distribution of these alleles across the different states. Demographic analysis also showed variations in allele prevalence based on gender and age but were not statistically significant.

Conclusion: The high prevalence of CQ-susceptible alleles, especially Pfmdr1 N86, suggests a reduction in CQ resistance in north-western Nigeria which aligns with trends observed in other regions where CQ-sensitive strains have resurfaced after the withdrawal of CQ. The results of this study suggest the possibility of (re)introducing CQ for malaria treatment in north-western Nigeria and provide insight into the genetic background of P. falciparum in the study area, especially if continuous surveillance and molecular monitoring are maintained. This is also a valuable tool in mitigating the threat posed by ACT resistance.