Transmission epidemiology and spatial characteristics of 1305 Chikungunya cases in Guangzhou, China from July to November 2025

From July to November 2025, Guangzhou, the capital city of Guangdong Province of China, went through a large-scale Chikungunya outbreak that 1305 cases were reported to Guangzhou Center for Disease Control and Prevention (Guangzhou Health Supervision Institute) by November 11. The epidemic presented two waves and was influenced by the public health control measures, population mobility and climate change. This study utilized the detailed epidemiological investigation report of each reported case, and presented in-depth analyses based on these data. Symptoms and viral load were found to be differed by age groups, rash occurred more in younger age groups while joint ache occurred more in older age groups; within 0–1 day of developing symptoms, 18–25 years had lowest viral load while > 65 years had highest viral load. Mean intrinsic incubation period was 4.58 days (95%CI: 3.87-5.32), while mean serial interval was 8.41 days (95% CI: 5.36-11.95). The Chikungunya cases at spatial-temporal scale were clustered rather than randomly distributed, high incidence areas were closely located. The odds of case dependence (>0.6) was highest within 0.25 km and decreased with extended distance. These findings from a metropolitan city in Southern China provided insightful information for future vector-borne disease outbreak control.