Molecular Epidemiology of Plasmodium falciparum Chloroquine Resistance Transporter Genes among School Children in Kwara State, Southwestern Nigeria

Background: Plasmodium falciparum existence continues to develop resistance to conventional antimalaria drugs in malaria endemic areas. Plasmodia often prevent drugs from interacting with the target site, hence, developing resistance to antimalaria drugs. Mutations in the Plasmodium falciparum chloroquine resistance transporter (Pfcrt), are the major determinant of chloroquine resistance in human malaria parasite.

Methodology: Malaria infection, Pfcrt and Pfmdr1 genes of isolates among school students within the age range of 11-22 years from four selected rural communities of Kwara state were studied. One hundred and eighty seven subjects (187) were selected for the study. Blood samples were collected by finger prick method for malaria screening. Nested PCR and restriction fragment length polymorphism (RFLP) were done to detect alleles of pfcrt at codon 76 and pfmdr1 at codon 86. DNA of isolates was appropriately extracted from the filter paper blots using the methanol fixation method. Logistic regression was performed on the binary observations obtained while linear regression was conducted on the fifty (50) subjects that tested positive to malaria.

Results: Out of 187 subjects screened, 26.7% (50) were positive to P. falciparum. Highest malaria parasite count of 36.4% was recorded in 14-16 years age group while 20-22 years age group had the least malaria parasite count (15.4%). The result of the studied isolates indicated that out of 50 isolates analyzed for Pfcrt gene, wild type alleles accounted for 32% (16) while mutant alleles accounted for 68% (34). Alakuko Community accounted for the least number of T76 mutant alleles 10% (5) while Apado community recorded the highest number of T76 mutant gene 22% (11). For Pfmdr1 gene analysis at codon 86, isolates from Apado community showed the highest mutant type alleles (Y86) of 22% (11), while Igbonla community in Ifelodun local government had the least mutant alleles, 6% (3).

Conclusion: The overall result revealed existence of mutant alleles in both the Pfcrt and Pfmdr1 genes which was higher than the wild type gene in both cases. The presence of chloroquine resistance genes among the studied population implies that alternative antimalaria drugs should be designed by pharmaceutical industry.