Sex, Age, and Urban Context: Modeling Social and Demographic Drivers of Mumps Transmission in Chengdu, China (2008–2019)

Objectives This study investigates mumps epidemiology in Chengdu (2008–2019), focusing on sex and age-specific transmission characteristics. Methods A sex- and age-specific Susceptible – Exposed – Pre-symptomatic – Symptomatic Infected – Asymptomatic Infected – Recovered (SEPIAR) model, adjusted for seasonal variations, was employed to categorize the population and analyze transmission dynamics. Results Over the study period, 40,087 mumps cases were reported in Chengdu, with an annual incidence of 21.72 per 100,000, peaking in 2011 at 40.83 per 100,000. Incidence rates were highest among male students aged 5–14, with significant seasonal peaks in May-July and November-December. District-wise, Wenjiang and Jinniu had the highest rates (45.45 and 43.25 per 100,000), while Jianyang city had the lowest (3.26 per 100,000). The SEPIAR model demonstrated robust fitting across demographics ( R ² = 0.13–0.73, P  < 0.001). Notably, females aged 10–14 exhibited the highest transmission risk to males aged 0–14, with all mean time-varying reproduction numbers ( R _t ) exceeding 1. The median R _t for females aged 10–14 to males aged 5–9 was 1.18, to males aged 0–4 was 0.75, and within the same age group was 0.55. Conclusions This study underscores the critical role of sex and age in mumps transmission and validates the utility of the SEPIAR model for outbreak analysis. To mitigate transmission, we recommend: 1) targeted vaccination campaigns during seasonal peaks, 2) prioritizing booster doses for females aged 10–14, 3) strengthening surveillance in high-incidence districts, and 4) improving healthcare reporting in rural regions. These strategies are vital for achieving sustained mumps control in megacities.