Circulation patterns and molecular epidemiology of human respiratory syncytial virus over five consecutive seasons in Morocco

Abstract

BackgroundRespiratory syncytial virus (HRSV) is the leading cause of respiratory tract infections in infants and young children. we investigated the prevalence and characteristics of HRSV in Morocco and explored trends in circulating genotypes through partial G gene analysis of HRSV strains prevalent from 2012 to 2017.MethodsRespiratory samples were gathered from both outpatients and inpatients meeting ILI or SARI case definitions. The patients' ages varied from 1 month to 99 years old. Nucleic acids were extracted and HRSV type/subtype was detected by RT‐qPCR. A subset of positive samples was randomly selected in each epidemic year, the complete viral genome was sequenced, phylogenetic analysis was performed using the MEGA7 program and the genotypes were confirmed.ResultsThe 3679 specimens were collected from 2012 to 2017, of which 726 (19.7%) were positive for HRSV. The 35% (257/726) of HRSV‐positives were of the HRSV‐A subtype, while the HRSV‐B subtype accounted for 61% (442/726). The co‐infection rate was 3.7% (27/726). The virus circulates in a periodic pattern, where epidemics occur during the fall months through early spring. HRSV genotype was confirmed in 127 specimens (56 HRSV‐A and 71 HRSV‐B). Based on phylogenetic analysis, all HRSV‐A were ON1 genotype, and HRSV‐B were mostly BA9 genotype. HRSV‐B belonging to the BA10 genotype was detected in 2012 exclusively.ConclusionsBA9, BA10, and ON1 were the only HRSV genotypes detected between 2012 and 2017. Variations in the G gene amino acid chain were identified in local strains, which suggests an increased need for continuous genomic surveillance.

Resurgence of respiratory syncytial virus with dominance of RSV-B during the 2022–2023 season

“…Among all the studied respiratory viruses, RSV was the most frequently identified etiologic agent of ARIs during the 2022–2023 season and the second most commonly detected respiratory virus after SARS-CoV-2 during the previous two seasons. Temporal and geographic variations exist in the incidence of RSV infection, depending on the study population, detection methods, climate, and other factors ( Gimferrer et al, 2019 ; Valley-Omar et al, 2022 ; Bimouhen et al, 2023 ; Kim et al, 2023 ). During the COVID-19 pandemic, the intensity of the applied anti-epidemic measures has played a crucial role in determining the spread of seasonal respiratory viruses.…”