Abstract: Objective To describe the epidemiological characteristics of hand, foot, and mouth disease (HFMD) among children under seven years of age in Haining from 2009 to 2024 and to forecast the incidence trend for 2025, thereby providing a scientific basis for the formulation of prevention and control strategies. Methods Data on HFMD cases in children under seven in Haining from 2009 to 2024 were collected from the Information Management System for Infectious Disease Reporting of the Chinese Center for Disease Control and Prevention. Descriptive statistical methods and a Joinpoint regression model were employed to analyze the epidemiological characteristics of the disease. A Seasonal Autoregressive Integrated Moving Average (SARIMA) model was developed to model and forecast the incidence rate. Results A cumulative total of 20 847 HFMD cases were reported in Haining from 2009 to 2024 among children under seven, with an average annual incidence rate of 2 507.04 per 100 000 population. Regarding temporal distribution, the incidence exhibited a bimodal pattern with peaks occurring from May to July and from September to November. A statistically significant difference was observed in the average daily incidence across the week (χ²=60.786, P<0.05), with the highest incidence on Mondays, followed by a decreasing trend (χ² for trend=36.522, P<0.05). The annual incidence demonstrated an alternating pattern, with even-numbered years showing higher incidence from 2009 to 2018, whereas odd-numbered years exhibited higher incidence from 2019 to 2024. Cases were predominantly concentrated in infants and toddlers aged 1 to <4 years, accounting for 62.54% (13 037 cases) of the total. The 1 to <2 years age group had the highest incidence rate at 4 327.60 per 100,000, which subsequently decreased with advancing age (χ² for trend=3 143.740, P<0.05). The incidence rate in boys (2 865.06 per 100 000) was significantly higher than that in girls (2 124.34 per 100,000) (χ²=466.132, P<0.05). Enterovirus A71 (EV-A71) was identified as the predominant pathogen (38.38%). The SARIMA(2,0,0)(0,1,1)₁₂ model was determined to be the optimal fit, forecasting that the incidence in 2025 will exceed that of 2024 and will likewise display a bimodal distribution. Conclusion The incidence of HFMD in children under seven years of age in Haining demonstrates clear periodicity. Dispersed children aged 1 to <2 years constitute the highest-risk population, and EV-A71 is the dominant etiological agent. The SARIMA model proves effective for short-term forecasting of incidence trends. It is recommended that public health campaigns for the EV-A71 vaccine be intensified and that surveillance, prevention, and control interventions be enhanced for key populations and regions.

Key words: Hand, foot, and mouth disease, Children, Epidemiological characteristics, SARIMA model