Temperature effect on scrub typhus incidence in South Korea: the projection for climate change.

Objective: The influence of climate change on infectious disease dynamics is a subject of interest, but it demands robust scientific evidence. This study explores the short-term and long-term relationships between meteorological factors and the incidence of scrub typhus (ST) in South Korea.

Methods: From 2001 to 2018, data on meteorological conditions and weekly ST cases were sourced from national databases. A generalized additive model was used to visualize the relationship, while a generalized linear model was applied to measure the association's strength. Mean annual temperature change was used as a proxy for climate change in long-term analysis. Despite the small sample size, generalized and mixed-effect models were employed to minimize geographical effects.

Results: The number of ST cases was linearly related to the mean temperature 13 weeks prior, above a threshold temperature of 13.3-18.5°C. A 0.1°C increase in mean temperature was associated with a 25% increase in ST cases (OR 1.25, 95% CI: 1.21, 1.29). In line with the short-term trend, the annual incidence of ST increased by 33% (OR 1.33, 95% CI: 1.26, 1.41) for every 0.1°C increase in annual mean temperature compared to the previous 30 years.

Conclusions: Higher mean temperatures during summer were associated with the increased ST cases in the following autumn. Annual mean temperature increases compared to 30 years ago were also associated with higher annual incidence of ST. These findings suggest that global warming has influenced the incidence of ST.