Dynamics of Plasmodium falciparum genetic diversity in symptomatic and asymptomatic children in three endemic areas of Gabon

Background Malaria cases in Gabon vary, from asymptomatic infection to severe malaria. The present study explores the allelic diversity of the merozoïte surface protein genes Pfmsp1 and Pfmsp2 among Plasmodium falciparum isolates in three endemic areas, and their potential correlation with virulence. Methods This cross-sectional study involved elementary schools in Gabon's urban, semi-urban and rural areas. 102 samples were analysed using PCR to examine Pfsmp1 and Pfmsp2. Results Forty-seven allele types were identified in the Pfmsp1 block, K1 allele type was the most prevalent (72.2%), followed by the RO33 allele type (49.5%) and the Mad20 allele type (36.6%). Forty-four alleles were detected in Pfmsp2 ; the FC27-like allele was the most prevalent (74.6%), followed by the 3D7-like allele (50.7%). The Mad20 allelic family was more prevalent in symptomatic isolates than in asymptomatic ones. Some Mad20, K1 and RO33 genotypes were found only in symptomatic patients, while other genotypes were found only in asymptomatic patients. The number of Pfmsp-1 and Pfmsp-2 genotypes per isolate ranged from 1 to 5 and 1 to 4, respectively. The MOI ranged from 1.95 to 2.78. The diversity index ( He ) ranged from 0.6 to 0.9 for both genes and was higher for Pfmsp_2 than for Pfmsp-1. The estimated fixation index (Fst) per site was 0.08202, 0.10413 and 0.13634 between Franceville/Lastoursville, then between Lastoursville/Makokou and finally between Franceville/Makokou. Conclusion The study revealed genetic diversity in the area, with some genotypes being asymptomatic and others symptomatic. ​This data could help develop a vaccine to reduce the disease.