Abstract
BACKGROUND: Herpangina is an acute pediatric illness caused by enteroviruses, yet the predominant circulating serotype in mainland China has not been well characterized. In this study, Coxsackievirus A2 (CV-A2) emerged as the dominant serotype among herpangina cases in Yuhuan City, Zhejiang Province. These findings underscore the importance of further research into the epidemiological distribution and molecular features of CV-A2 in this region. METHODS: A total of 133 child herpangina cases were included during May and June 2024. Enteroviruses were detected using RT-PCR, followed by serotyping and sequencing. Phylogenetic and recombination analyses were performed to assess genetic diversity and evolutionary relationships. RESULTS: Among the 133 cases (median age: 3 years), 88.7% tested positive for enteroviruses. CV-A2 was predominant (78.0%), followed by CV-A4, CV-A5, CV-A10, CV-A16, and CV-B4. Fever (95.5%) and oral vesicles (98.5%) were the most common symptoms. Compared to other serotypes, CV-A2 cases had a higher incidence of fever (P = 0.008) and peak temperature (P = 0.042), with significantly elevated neutrophil percentages (> 70.0%) and reduced lymphocyte percentages (< 20.0%). Phylogenetic analysis identified genotype D accounted for 97.8% (90/92) of CV-A2 strains; two genotype C strains clustered with European isolates. Recombination analysis revealed intra- and inter-serotype events involving CV-A2, A4, and A5. CONCLUSION: CV-A2 has re-emerged as the dominant herpangina-associated enterovirus in Eastern China, demonstrating distinct clinical and hematological features. This shift in serotype prevalence underscores the need for continued surveillance to monitor its spread and interactions with other serotypes.