JMIR Publications

ABSTRACT

Background:

Scrub typhus (ST), also known as tsutsugamushi disease, is a common febrile vector-borne illness in South Korea, with rodents being the main host. Previous studies have often lacked integrated spatiotemporal analyses covering disease dynamics, vectors, and environmental shifts.

Objective:

We aimed to explore spatiotemporal high-risk areas and risk factors of ST by simultaneously incorporating host and environmental information.

Methods:

ST cases were extracted from 2013–2019 Korea National Health Insurance Service data at 250 municipal levels. Spatial and temporal clusters were assessed using Getis-Ord G_i^* and Hot and cold spot trend analyses. Bayesian hurdle models with spatiotemporal interaction term identified associations between ST incidence and diverse regional factors, including rodent suitability, human, and environmental factors. Stratification by gender and age group (0–39, 40–59, 60–79, and ≥80 years) was performed.

Results:

Between 2013 and 2019, 95,601 ST patients were reported. ST incidence had positive spatial autocorrelation (I=0.600, p=0.01), with spatial expansion from southwestern to northeastern regions. Municipalities with higher rodent suitability (coefficient=0.225, 95% credible interval=0.118–0.330), forest area (coefficient=0.261, 95% credible interval=0.121–0.403), and worse financial independence against central government (coefficient=-0.258, 95% credible interval=-0.323 to -0.193) had higher likelihoods of increased ST incidence, even after adjusting for spatiotemporal autocorrelation. However, risk factors varied by age group: incidences in those ≥40 age groups were positively associated with rodent suitability, while the 0–39 group showed no association and was negatively associated with the women farmer population (coefficient=-0.115, 95% credible interval=-0.223 to -0.006).

Conclusions:

We elucidated the critical role of spatiotemporal dynamics in scrub typhus distribution, highlighting rodent suitability, forest coverage, and economic independence as key factors. Our findings lay the groundwork for evidence-based strategies to tackle ST, integrating both a holistic One Health and spatiotemporal perspective.