Objective To analyze the epidemiological and etiological characteristics of hand-foot-and-mouth disease (HFMD) in Jinjiang District of Chengdu City from 2014 to 2024, and to provide a reference basis for HFMD prevention and control.

Methods A retrospective study was conducted to collect confirmed and clinically diagnosed cases of HFMD in Jinjiang District from January 1, 2014 to December 31, 2024. Descriptive epidemiological methods were used to analyze the distribution of cases by person, time, and place. Joinpoint regression models were applied to examine trends for incidence and severe case rates, while seasonal patterns were analyzed using the seasonal index method. Chi-square tests were used for comparing rates, Mann-Whitney U tests were applied for comparing two groups with skewed distributions, and Kruskal-Wallis H rank-sum tests were used for multiple groups with skewed distributions. Pathogen characteristics were primarily analyzed using descriptive statistics.

Results A total of 15 561 HFMD cases were reported from 2014 to 2024. The annual crude incidence rate ranged from 51.32/100 000 to 502.50/100 000, the age-standardized incidence rate ranged from 55.56/100 000 to 721.07/100 000, peaking in 2018, and the overall epidemic intensity generally showed an alternating-year pattern of intensification. A total of 85 severe cases were reported, showing a declining trend in the severe case rate (APC=AAPC=-37.57%, 95%CI∶ -51.49%‒21.33%， P<0.01). Severe cases were most common in the 1‑year‑old age group (43.53%), with a median age of 1.88 years. Recurrent infections accounted for 1 245 cases (8.00%), with 96.73% of these being reinfections. The median age at first infection for recurrent cases was 1.98 years, significantly lower than that of single-infection cases (2.69 years, P<0.001), and the median interval between consecutive infections was 1.19 years. The disease exhibited a bimodal seasonal pattern, with epidemic peaks occurring from May to July and from October to December, however, summer peaks extending into autumn were observed in 2018 and 2023. There were statistically significant differences in age distribution across different years (H=467.51, P<0.001), with the median age increasing from 2.25 years in 2018 to 4.18 years in 2024, and the interquartile range widening from 1.84 to 3.78 years. Since its initial detection in 2017, CVA6 has been identified annually, showing a peak proportion of 87.50% in 2023 and a second peak of 68.18% in 2018. CVA10 was detected during 2021‒2023, peaking at 18.75% in 2021 and decreasing to 14.29% in 2022. Male incidence rates were consistently higher than female rates each year (P<0.05). The proportion of males in the reinfection group was significantly higher than that in the single-infection group (χ²=9.951, P=0.002). Pathogen analyses showed that CVA16 was detected annually, EV71 detection declined fluctuantly and was not detected after 2022. CVA6 was first detected in 2017 and rapidly increased in prevalence, reaching 87.50% in 2023 and becoming the dominant strain. Among severe cases, EV71 accounted for the highest proportion (52.63%), while CVA16 was most common in non-severe cases (41.60%). There was a statistically significant difference in pathogen composition between severe and non-severe cases (χ²=10.402,P=0.011).

Conclusion The epidemiological profile of HFMD undergoes continuous changes over time. It is necessary to strengthen routine surveillance, with particular attention to changes in the pathogen spectrum and age distribution, so as to provide evidence for precise prevention and control measures and the adjustment of vaccination strategies.