Abstract:

Objective To investigate the composition and prevalence of hand-foot-mouth disease (HFMD) in Shaanxi province from 2020 to 2022. Methods Nucleic acid detection results and case data of HFMD surveillance cases in cities of Shaanxi province were collected. Positive samples of enterovirus nucleic acid detection were isolated. PCR amplification, sequence determination and gene subtype identification of enterovirus VP1 region of epidemic dominant pathogen were performed. Results From 2020 to 2022, a total of 6 352 samples of HFMD cases were collected in Shaanxi province, and 4 417 samples tested positive for enterovirus nucleic acid, with a positive rate of 69.54%. In 2020 and 2021, other enteroviruses excluding EV-A71 and EV-A16 were the main epidemic types, with a composition ratio of 95.43% and 74.35%, respectively. In 2022, CV-A16 was the main epidemic type, with a composition ratio of 52.88%. CV-A6 and CV-A10 types of other enteroviruses were detected in 4 145 laboratory confirmed cases of HFMD in 8 cities. CV-A6 accounted for 75.31%, 62.56% and 61.15% of other enteroviruses, which was the dominant epidemic type of other enteroviruses in Shaanxi province. From 2020 to 2022, 239 isolates, 151 CV-A16 isolates, 72 CV-A6 isolates, 6 CV-A10 isolates, 2 CV-A4 isolates and 8 CV-B3 isolates were sequenced in Shaanxi province. CV-A16 and CV-A6 were the main epidemic types. According to phylogenetic analysis, the D3 subtype was the main epidemic subtype of CV-A6, while B1a and B1b coexisted for CV-A16. The proportion of B1a subtype increased year by year in 2021 and 2022, and it replaced B1b as the main epidemic subtype. Conclusion From 2020 to 2022, the prevalence of HFMD in Shaanxi province is at a lower level than that in previous years, and the main pathogens are other enteroviruses and CVA16.

Key words: hand, foot and mouth disease, enterovirus, pathogen composition, phylogenetic analysis, Shaanxi