[Epidemiological and etiological characteristics of herpes pharyngitis in 3 prefectures in Jiangsu Province]

Objective: To analyze the epidemiological and etiological characteristics of herpes pharyngitis (HA) in three prefectures of Jiangsu Province, and provide evidence for the prevention and control of HA in Jiangsu. Methods: Three surveillance sentinel hospitals in Wuxi, Suzhou and Yancheng were selected from May 2018 to December 2022, and information related to HA visits and hospitalized cases was regularly collected from the hospital inpatient management system by age groups. Enterovirus nucleic acid detection was performed by RT-PCR, and sequencing analysis, identification of genotype subtypes, and phylogenetic analysis were performed on the sequences of the gene encoding the coat protein VP1 of the main prevalent strains. Results: A total of 57 709 HA cases were recorded in the sentinel hospitals in in Wuxi, Suzhou and Yancheng, which was 1.76 times higher than the reported cases of hand, foot and mouth disease during the same period (57 709/32 831).The percentage of HA hospitalizations was 1.35% (781/57 709), and the percentage of hospitalizations showed an increasing trend from year to year (χ²=62.79, P<0.001 ).The incidence peak of HA was during May-July. The cases were mainly children aged 12-59 months (67.07%, 38 708/57 709), with the highest case number in age group 36-59 months (34.40%, 19 852/57 709). The HA positivity rate was 33.82% (644/1 904); enterovirus A was predominant (54.04%, 348/644); of these, Coxsackievirus (CV)A6 accounted for the highest percentage (52.59%, 183/348), while CVA16 and CVA4 accounted for 24.71% (86/348) and 15.23% (53/348), respectively. All 10 CVA4 HA endemic strains belonged to the C2 gene subtype, and all 6 CVA6 HA endemic strains belonged to the D3a gene subtype; and were genetically closer to and related to the strains in some areas of China (Fujian Province, Guangzhou City, Jiangxi Province, Yunnan Province, Tianjin City, etc.). Conclusions: The disease burden of HA was heavy in 3 areas in Jiangsu, children in age group 12-59-month were mainly affected, and the annual incidence peak of HA was during May-July. The pathogens causing HA varied, but predominated by enterovirus A and had low intra-typical differentiation, and no new evolutionary branches were found, suggesting that it is necessary to include HA in foot and mouth disease surveillance or regarded as a notifiable communicable disease.