Epidemiological, Clinical and Viral Genomic Features of Influenza Virus Infections Among Pilgrims During the Grand Magal of Touba Over 7 Years (2018–2024)

Résumé fourni par la source

Large international gatherings such as the Grand Magal of Touba in Senegal may favor influenza A/B virus (IABV) transmission. We analyzed IABV genomes from human samples collected during the event in 2018-2024. Next-generation sequencing was performed for 190 qPCR-positive nasopharyngeal samples. Bioinformatic analyzes were performed using MAFFT v7.505, IQ-TREE v2.2.0, iTOL, Nextclade, and PREDAV-FluA. 106 (55.8%) complete genomes were obtained, including 99 type A and 7 type B. IAV genomes were classified as A/H3N2 (N = 48) and A/H1N1 (N = 43), based on hemagglutinin/neuraminidase-encoding segments. A/H3N2 was not detected in 2021 and 2023; A/H1N1 was only detected in 2018, 2021 and 2023. Phylogenies classified A/H3N2 and A/H1N1 into distinct clades varying from 1 year to the next. A single A/H1N1 sequences was predicted to be antigenic divergence from the vaccine strain concomitantly used. All IBV genomes (clades V1A.3a or V1A.3a.2) were from 2020. Some IABV genomes from the GMT were clustered together while the most similar genomes from databases were from Senegal, Subsaharan Africa or other countries. Present data describes the circulation of IABV during the GMT over time in the population studied here shedding light on the viral dynamics in such setting of mass gathering.

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