# Non-negligible impacts of urbanization on spatiotemporal variations of infectious disease: a case study of hemorrhagic fever with renal syndrome epidemics in China

## TL;DR

This study explores how urbanization affects the spread of a kidney disease in China, finding that while climate and vegetation are main factors, urbanization also plays a notable role.

## Contribution

The study reveals that urbanization synergizes with climate factors to influence disease spread, a novel insight for public health planning.

## Key findings

- HFRS incidence in China showed an overall decline from 2005 to 2021, with regional variations.
- Urbanization factors alone explained only 3–5% of disease spread but synergized with climate factors to enhance explanatory power.
- Upward-trend cities were mainly in South China, with climate-urbanization interactions increasing explanatory capacity by 124–184%.

## Abstract

Hemorrhagic fever with renal syndrome (HFRS) poses a significant public health concern in China. However, the spatiotemporal patterns and underlying drivers of its transmission are not fully understood. This study aims to investigate spatiotemporal heterogeneity of HFRS incidence at the city level and explore its potential influencing factors.

Joinpoint regression was utilized to analyze city-level HFRS incidence data (n = 314 cities, 2005–2021) collected from the National Infectious Disease Surveillance System. Furthermore, we employed the Geodetector method to identify the potential driving factors from a set of meteorological, vegetation, and urbanization variables.

The results from Joinpoint regression analysis revealed an overall declining trend in city-level HFRS incidence across China from 2005 to 2021. Of the cities analyzed, 126 showed an upward trend [the average annual percent change,(AAPC) > 0], 176 a downward trend (AAPC < 0), and 12 remained stable (AAPC = 0). Notably, upward-trend cities were predominantly concentrated in South China. Geodetector analysis indicated that selected climatic and vegetation factors accounted for 19–56% of the spatiotemporal heterogeneity in HFRS incidence, whereas urbanization factors explained only 3–5%. However, synergistic interactions between temperature and urbanization-related variables (i.e., land-use, economic, and demographic dimensions) significantly enhanced their explanatory power, particularly in upward-trend cities, where the combinations increased explanatory capacity by 124–184%.

In summary, while climatic and vegetation factors remain the primary drivers of the spatiotemporal heterogeneity of HFRS epidemics in China, urbanization also exerts non-negligible influence on city-level incidence. This research offers valuable insights for public health authorities to strengthen their intervention capabilities against this disease.