Abstract
BACKGROUND: Scrub typhus is an important zoonotic disease with rising incidence globally. Meteorological factors may influence its transmission dynamics. However, inconsistencies across studies and limited quantitative evidence highlight the need for further investigation. OBJECTIVE: To systematically evaluate the linear and nonlinear associations between various meteorological factors and scrub typhus incidence, explore lagged effects and potential sources of heterogeneity, and analyze inconsistencies in existing findings. METHOD: We searched PubMed, Scopus, Web of Science, and Embase for studies published up to February 2025. Relevant articles were identified based on predefined inclusion and exclusion criteria. We conducted linear meta-analyses to assess the effects of unit changes in meteorological factors and dose-response meta-analyses to evaluate cumulative lagged risks across different exposure levels. Subgroup and sensitivity analyses were conducted to explore sources of heterogeneity and assess result robustness. RESULTS: Seventeen studies were included, covering China, Korea, Laos, and India. Eleven studies contributed to linear meta-analyses, and six to dose-response analyses. Ambient temperature (RR 1.08, 95% CI 1.02-1.16), land surface temperature (RR 1.06, 95% CI 1.02-1.09), precipitation (RR 1.01, 95% CI 1.01-1.02), relative humidity (RR 1.07, 95% CI 1.04-1.11), and atmospheric pressure (RR 1.06, 95% CI 0.91-1.23) were positively associated with the risk of scrub typhus. Wind speed (RR 0.59, 95% CI 0.49-0.71) and sunshine duration (RR 0.92, 95% CI 0.77-1.10) exhibited negative associations. Dose-response meta-analysis revealed inverted U-shaped relationships for ambient temperature and relative humidity, and a unimodal pattern for precipitation, with risk increasing continuously at high levels. Significant lag effects were observed: precipitation had the most immediate effect (lag0: RR 1.05), while ambient temperature (lag1: RR 1.18) and relative humidity (lag2: RR 1.28) peaked with a 1- to 2-month delay. Geographic variation was identified as a major source of between-study heterogeneity. CONCLUSION: Although this study has certain limitations, including the small number of included studies, their concentration mainly in China, and the presence of substantial heterogeneity, the results provide evidence of linear and nonlinear associations between meteorological factors and scrub typhus incidence, and highlight the roles of geographical variation and lag effects. These findings offer quantitative evidence and scientific support for disease prevention and control in the context of climate change.