Epidemiology of Hand, Foot, and Mouth Disease and Genetic Evolution Dynamics of Coxsackievirus A6 in Taiyuan, Shanxi, China From 2017 to 2024.

Hand, foot, and mouth disease (HFMD) is a common infectious disease in children, primarily caused by human enteroviruses (EVs). This study describes the epidemiological characteristics of HFMD in Taiyuan, China (2017-2024), also the genetic features of Coxsackievirus A6 (CVA6). The incidence of HFMD showed significant variations during this period. Male cases outnumbered females, with children aged 0-6 years accounting for 81.88% of all cases and exhibiting a distinct seasonal distribution pattern. Real-time reverse transcription polymerase chain reaction was performed on 4389 clinical specimens, identifying 1,920 human EVs-positive specimens. Positive cases included 690 CVA6, 530 CVA16, 65 CVA10, 152 Enterovirus A71, and 483 other human EVs. Pathogen spectrum analysis revealed that CVA6 maintained high prevalence from 2017 to 2023 but declined in 2024. Phylogenetic analysis of 194 complete VP1 sequences revealed all strains belonged to sub-genotype D3 within genotype D. Nucleic acid homology ranged from 91.4% to 100%, and amino acid similarity from 97.0% to 100%. A persistent, continuously circulating lineage existed within the D3a branch. The GH loop within VP1 revealed high sequence conservation and structural stability, confirming its suitability as a vaccine target. These findings enhance genetic data on CVA6, thereby providing crucial scientific basis for prevention and vaccine development.