Systematic review of environmental factors associated with severe fever with thrombocytopenia syndrome occurrences in humans

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease with high fatality risk in older adults, posing a growing public health threat in East Asia and potentially beyond. Yet, the role of environmental drivers in its transmission remains poorly understood, limiting effective control strategies. We systematically reviewed evidence on associations between environmental factors and SFTS occurrence in vectors, animals, and humans. Our review suggests that temperature, humidity, precipitation, elevation, and land cover are linked to human SFTS occurrence through non-linear—often reverse U-shaped—relationships, underscoring the need for analytical approaches that capture such dynamics. Notably, no study has examined environmental impacts on SFTS occurrences in vectors or non-human reservoirs, nor disentangled impacts across different stages of the transmission cycle. With the potential for geographic expansion under global climate change, addressing these gaps is essential to developing ecologically grounded surveillance and intervention strategies to mitigate the escalating threat of SFTS.