Landscape wetness and beaver wetlands enhance environmental prevalence of Francisella spp.

Abstract

Identifying the contributions of biotic and abiotic factors in pathogen transmission is essential to mitigate vector‐borne and zoonotic disease risk. Francisella tularensis is the etiological agent of the infectious disease tularemia in wildlife and humans. Environmental factors driving transmission in wildlife, including the role of hares and beavers, are largely unknown, as are causes of increasing human incidence of tularemia in Europe. We tested whether the degree of wetness in the landscape is related to tularemia status in hares, found dead in 2016–2021 ( n  = 428), and whether the occurrence of F. tularensis in water varies between beaver wetlands ( n  = 14) and non‐beaver wetlands ( n  = 14). Latitude, landscape coverage of lakes, streams, and open wetlands, as well as soil moisture, contributed to explaining infection in hares. Notably, F. tularensis and/or Francisella spp. was polymerase chain reaction (PCR)‐detected in water of three beaver wetlands, but not in non‐beaver wetlands. Our results suggest that wetlands, especially beaver wetlands, play an important role in the transmission cycle of F. tularensis . This finding raises concern regarding the potential role of wetland rewetting and beaver wetlands in amplifying tularemia transmission in wildlife and humans.