48 / 2025-03-13 20:43:08

The Epidemiological Characteristics and its Associated Driving Factors of Tuberculosis Among Migrant Populations in Zhejiang Province

Tuberculosis; Migrant Populations; Boosted Regression Trees Model; Epidemiological Characteristics; Driving Factors

Background

Tuberculosis (TB) remains a global health priority, with increased population mobility exacerbating its transmission risks. As a major immigration hub in China, Zhejiang Province has become a critical region for the importation of TB cases. This study aims to explore the epidemiological characteristics of TB in Zhejiang and identify the key driving factors associated with its transmission.

Methods

TB surveillance data sourced from the TB Information Management System (TBIMS) in Zhejiang Province (2005–2023) was analyzed using joinpoint regression, age-period-cohort modeling, and spatial autocorrelation to examine incidence trends and disparities between migrant and local cases. The Boosted Regression Trees (BRT) model identified key socioeconomic and demographic driving factors of TB among migrant populations.

Findings

Between 2005 and 2023, Zhejiang Province experienced declining TB incidence (average yearly incidence 61.35 per 100,000), yet migrant cases comprised 34.48% of reported cases. Migrant cases exhibited younger age (36.0 ± 15.2 vs. 51.4 ± 19.6 years) and higher worker proportion (51.4% vs. 8.6%). The incidence initially increased during 2005–2007 at an annual percent change (APC) of +2.76%, followed by sustained decline thereafter (APC = -4.12%), while migrant proportions demonstrated steady growth until 2019 (APC = +5.83%) followed by accelerated reduction during 2019–2023 (APC = -17.62%). There were bimodal age effects (peaks aged 15–19 and 80–84 years) and declining period effects on TB incidence, and a birth cohort effect with elevated risk in the 1954–1958 cohort and significantly reduced risks in the post-1974 cohorts. The incidence hot spots transitioned from Hangzhou to Quzhou. The hot spots for local cases persisted in Quzhou and Lishui, whereas the hot spots for migrant cases shifted to Ningbo and Jiaxing. The per capita gross regional product (GRP; 56.82%, 95%CI: 56.19–57.44), tertiary industry proportion (8.98%, 95%CI: 8.66–9.27) and emigration index (7.38%, 95%CI: 7.16–7.67) were identified as the primary driving factors of TB among migrant populations.

Interpretation

Although a sustained decline in TB incidence was observed among the local population in Zhejiang, migrant proportions demonstrated steady growth. Epidemiological patterns of TB incidence exhibited a bimodal age distribution and elevated risks in early birth cohorts. The incidence hot spots transitions showed divergent patterns between migrant and local cases. GRP, tertiary industry, and emigration index need to be considered as the primary driving factors to targeted screen among the origin-stratified migrant populations to mitigate transmission.