Objective To describe the epidemiological characteristics of recurrent cases of hand, foot, and mouth disease (HFMD) in Yunnan province from 2008 to 2022 to inform the development of prevention and control strategies.

Methods Records of HFMD cases diagnosed by various medical institutions in Yunnan province between May 8, 2008, and December 31, 2022, were collected via the Chinese Center for Disease Control and Prevention's Infectious Disease Information Reporting Management System. After cleaning and verifying the data, a database of recurrent HFMD cases was created. Then, we analyzed the temporal, regional, demographic, and pathogen distributions of the cases.

Results A total of 899 455 HFMD cases were registered during the study period, including 54 138 recurrent cases (cumulative recurrence rate: 6.02%). Of these recurrent cases, 97.84% involved two episodes, with a male-to-female ratio of 1.61:1. The median age was 3.74 years for cases involving two episodes and 4.43 years for cases involving three episodes. The peak season occurred from May to July. Second episodes were prevalent in 15 counties and districts, while third episodes were concentrated in Kunming′s urban area. Most recurrences involved different pathogens; only 4.97% of cases involved two consecutive infections of the same pathogen. Patients with severe symptoms in the first episode were at an increased risk of recurrent HFMD compared to patients without severe symptoms (relative risk = 1.80, 95% confidence interval: 1.71 - 1.91).

Conclusions The HFMD recurrence rate in Yunnan province was high and increased over time, exhibiting distinct temporal, demographic, and regional patterns. Improving pathogen surveillance is crucial for developing multivalent vaccines, and targeted measures should focus on severe cases and high-incidence areas.