Background: Artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) are first- and second-line treatments for uncomplicated Plasmodium falciparum malaria in Gabon. AL remains highly efficacious, but its widespread use has led to molecular selection of the NFD haplotype on Pfmdr1 and K76 in Pfcrt. In this study, plasmodial infection characteristics and the distribution of the Pfmdr1 and Pfcrt genotypes involved in reduced efficacy of artemisinin-based combination therapy (ACT) were investigated in four Gabonese localities. Methods: A cross-sectional study was conducted in the paediatric units of rural (Lastourville and Fougamou), semi-urban (Koula-Moutou) and urban (Franceville) areas. Malaria was diagnosed with the rapid diagnostic test Optimal-IT^® and confirmed by blood smear. Pfmdr1 codons 86, 184 and 1246 and Pfcrt codon 76 were genotyped by PCR–RFLP and sequencing. Results: Among 1129 included children, the prevalence of plasmodial infection was 79.5 % at Lastourville, 53.6 % at Fougamou, 36.1 % at Koula-Moutou, and 21.2 % at Franceville. The prevalence was significantly higher among children over 60 months of age in both semi-urban (p = 0.01) and urban (p = 0.004) areas. The prevalence of Pfmdr1 wild-type N86 differed significantly between Lastourville (57.8 %) and Koula-Moutou (45.4 %) (p = 0.039). No difference in 184F-carrying parasites was found between Lastourville (73.8 %), Fougamou (81.6 %), Koula-Moutou (83.2 %), and Franceville (80.6 %) (p = 0.240). The prevalence of wild-type D1246 was significantly different between Lastourville (94.1 %), Koula-Moutou (85.6 %) and Franceville (87.3 %) (p = 0.01). The frequency of wild-type K76 was not significantly different across the four sites: Lastourville (16.5 %), Fougamou (27.8 %), Koula-Moutou (17.4 %), and Franceville (29.4 %) (p = 0.09). The mixed genotypes were only found in Lastourville and Franceville. The NFD, YFD and NYD haplotypes were mainly Lastourville (46.6, 25.8, 14.0 %), Fougamou (45.5, 9.1, 42.4 %), Koula-Moutou (35, 6.7, 40.4 %), and Franceville (40.0, 16.0, 32.0 %). Conclusion: This study shows an increase in the prevalence of childhood plasmodial infection in Gabon according to the low socio-economic level, and a high frequency of markers associated with AL treatment failure. Close monitoring of ACT use is needed.

Objective: To characterize the profiles of resistance mutations to HIV reverse transcriptase inhibitors in Gabon. Design: Cross-sectional study conducted over 37 months, from October 2019 to October 2022, at the IST/HIV/AIDS Reference Laboratory, a reference center for the biological monitoring of people living with the human immunodeficiency virus (PWHIV) in Gabon. Methods: Plasma from 666 PWHIV receiving antiretroviral treatment was collected, followed by RNA extraction, amplification, and reverse transcriptase gene sequencing. Statistical analyses were performed using Stata^® 14.0 software (USA). Results: Six hundred and sixty-six (666) PWHIV plasma collected from 252 male and 414 female patients were analyzed and 1654 mutations were detected in 388 patients, including 849 (51.3%) associated with nucleoside reverse transcriptase inhibitors (NRTIs) and 805 (48.7%) with non-nucleoside reverse transcriptase inhibitors (NNRTIs). Three of the most prescribed treatment regimens were associated to the appearance of both NRTIs and NNRTIs resistance mutations: TDF + 3TC + EFV (24.02%; 160/666); TDF + FTC + EFV) (17.2%; 114/666) and AZT + 3TC + EFV (14.6%; 97/666). Additionally, stage 3 of CD4 T-lymphocyte deficiency, the higher viral load, and treatment duration are risk factors influencing the appearance of virus mutations. Also, treatment containing TDF-3TC + DTG is more protective against mutations. Conclusions: Drug resistance mutations are common in Gabon and compromise the efficacy of ART. Further study must search for other causes of therapeutic failure in Gabon in PWHIV.