Spatiotemporal dynamics and pathogen spectrum of other infectious diarrhea in Kunming, China from 2011 to 2025

Other infectious diarrhea (OID) is one of the most frequently reported notifiable infectious diseases in China. As the capital of Yunnan Province, Kunming serves as an important regional hub in Southwest China and a gateway to the Greater Mekong Subregion. Its patterns of regional population mobility and local disease transmission are complex and region-specific, making Kunming an informative setting for sentinel surveillance and epidemiological investigations. This study investigated the long-term epidemiological characteristics and pathogen spectrum changes of OID in Kunming from 2011 to 2025. Temporal, spatial, demographic and pathogen-related patterns were assessed using descriptive epidemiological analyses, time-series and trend analyses. Seasonal-trend decomposition using Loess (STL) was utilized to characterize long-term temporal trends and seasonal patterns of OID. Continuous wavelet transform was applied to identify periodic fluctuations and temporal changes in epidemic patterns. The Shannon-Wiener diversity index was used to evaluate changes in pathogen diversity. Joinpoint regression was performed to assess long-term incidence trends across different population groups. From 2011 to 2025, Kunming reported 152,090 OID cases, with a mean annual incidence of 134.3 per 100,000 population (range: 62.7-273.2 per 100,000). Incidence increased significantly over the surveillance period (AAPC = 11.2%, 95% CI 3.5 to 19.3), showing a marked acceleration after 2023. OID cases occurred across all age groups, with those aged 0-4 years accounting for the largest proportion (67.0%, 101,899/152,090), while incidence increased across all age groups (all P < 0.001). Among 38,902 laboratory-confirmed cases, viral infections predominated (99.2%). Rotavirus remained the most prevalent pathogen (69.7%), followed by norovirus (26.7%). Both were mainly concentrated among children aged 0-4 years (89.1% and 72.0%, respectively). Spatially, OID incidence varied across counties and districts, with increasingly synchronized regional increases observed in recent years, particularly after 2024. Our findings from routinely collected surveillance data indicate that OID epidemiology in Kunming has shifted from traditional epidemic fluctuations toward broader structural changes, characterized by expanding affected populations, evolving pathogen composition, and changing spatial epidemic patterns. Although the observed changes in pathogen composition may have been influenced by testing practices, the findings highlight increasing epidemiological complexity and emerging control challenges. Accordingly, prevention strategies should integrate population diversity, spatial differences, and pathogen composition.