Evolution of Plasmodium falciparum strains and resistance markers in pregnant women in Cameroon: 2008 - 2018 Acho FA1, Esemu LF1, Yukie LS2, Njobe BK1, Meyahnwi D1, Belanquale CA1, Bigoga J1, Mbacham W1, Leke FGR1 1Biotechnology Centre, University of Yaoundé I, 2Department of Tropical Medicine, University of Hawaii
The genetic diversity of Plasmodium falciparum and the prevalence of antimalarial drug resistance markers have been extensively studied in various parts of the world. However, limited data is available on the genetic diversity of parasite infections in pregnant women and the temporal trend in the prevalence of these drug resistance markers. Blood samples were collected from 60 pregnant women in 2018 who had not received IPTp-SP. Sixty more samples, collected during a previous clinical trial carried out in 2008, from pregnant without a history of IPTp-SP use were included to compose a total sample size of 120. K1, MAD20 and RO33 allelic families of Pfmsp-1 were genotyped by nested PCR amplification. The prevalence of Pfdhfr N51I, C59R, S108N and Pfdhps A437G, K540E point mutations was determined by RFLP - PCR. A high genetic diversity was observed at both time points with 31 genotypes observed in the 2008 group and 34 genotypes in 2018. In contrast to studies in the general adult population, no single allelic family predominated. There was a significant increase in overall multiplicity of infection (MOI) from 4.42±1.819 in 2008 to 5.35±1.74 in 2018 and a marginal increase in Expected Heterozygosity (HE) from 0.8733 in 2008 to 0.897 in 2018. We found an increase in prevalence of the Pfdhfr/Pfdhps N51I, C59R, S108N/A437G quadruple mutation from 52.2% in 2008 to 75.5% in 2018 (p = 0.05319). There was a complete absence of Pfdhfr/Pfdhps quintuple mutants at both time points. No significant association was found between parasite strain and drug resistance markers (p = 0.852). The genetic diversity of Plasmodium falciparum populations in pregnant women was high. There was a marginally higher MOI and HE in 2018 than in 2008. The MOI was higher in pregnant women than reported MOI values in the general population. Our study confirms a fixation of N51I and C59R mutations in Pfdhps and Pfdhfr genes. The increase in prevalence of Pfdhfr/Pfdhps N51I, C59R, S108N/A437G quadruple mutations could herald a gradual loss in effectiveness of IPTp-SP.