Spatial and temporal distribution of Pfmsp1 and Pfmsp2 alleles and genetic profile change of Plasmodium falciparum populations in Gabon.

Plasmodium population dynamics analysis may help to assess the impact of malaria control strategies deployment. In Gabon, new strategies have been introduced, but malaria is still a public health problem marked by a rebound of the prevalence in 2011. The aim of the study was to investigate the spatial and temporal distribution of P. falciparum strains in different areas in Gabon during a period of malaria transmission transition, between 2008 and 2011. A total of 109P. falciparum isolates were genotyped using nested-PCR of Pfmsp1 and Pfmsp2 genes. 3D7, FC27 and K1 allele frequencies were comparable between sites (p=0.9); those of Ro33 (93.6%; 44/47) and Mad20 (60%; 12/20) were significantly higher in isolates from Oyem (p<0.01) and Port-Gentil (p=0.02), respectively. The frequency of multiples infections (77%) and the complexity of infection (2.66±1.44) were the highest at Oyem. Pfmsp1 gene analysis highlighted a trend of a decreasing frequency of K1 family, in Libreville and Oyem between 2008 and 2011; while that of Ro33 (p<0.01) and Mad20 (p<0.01) increased. The prevalence of multiple infections was comparable between both periods in each site: 42.2% vs 47.6% (p=0.6) in Libreville and 57.7% vs 61.7% in Oyem (p=0.8). In contrast, in 2011, the COI tends to be higher in Libreville and did not vary in Oyem. These data confirm an extended genetic diversity of P. falciparum isolates over time and according to geographic location in Gabon. Nevertheless, the impact of the deployment of malaria control strategies on the parasites genetic profile is not clearly established here.