Epidemiological Characteristics and Spatiotemporal Cluster Analysis of Scrub Typhus - China, 2006-2023

Scrub typhus, also known as jungle typhus, is a vector-borne disease transmitted to humans through the bite of infected chiggers carrying Orientia tsutsugamushi. In recent years, it has reemerged as a significant public health concern in China, with cases being identified in an increasing number of previously unaffected regions.

Data were obtained from the China Information System for Disease Control and Prevention (CISDCP). We employed Joinpoint 5.1.0 for trend analysis and RStudio 4.4.1 for statistical analyses, including Mann-Whitney U tests (non-parametric), Cochran-Armitage tests, and binary logistic regression. SaTScan 9.1.1 and ArcGIS 10.7 were utilized to identify high-risk spatial clusters.

Scrub typhus incidence in China increased dramatically from 0.095/100,000 to 2.357/100,000 between 2006 and 2023. The epidemic trend was categorized into 3 distinct phases: a rapid increase period [APC_2006-2013=37.1%, 95% confidence interval (CI): 31.4%, 43.0%], a slow increase period (APC_2014-2018=13.4%, 95% CI: 4.6%, 23.0%), and a peak-plateau period (APC_2019-2023=-0.2%, 95% CI: 3.2%, 3.0%), with annual cases ranging from 24,870 to 33,229. The proportion of individuals aged ≥45 years demonstrated an increasing trend (AAPC=2.0%). We identified 3 distinct seasonal patterns across China: summer, autumn, and summer-autumn patterns. This study revealed distinct spatiotemporal characteristics of scrub typhus in China, with the primary cluster concentrated in Yunnan Province and geographic expansion from southwestern, southern, and eastern regions toward central and northern China.

Scrub typhus incidence in China has increased substantially and has reached a peak plateau phase. The disease exhibits distinct spatiotemporal distribution patterns, necessitating targeted control measures in affected regions.