Peromyscus maniculatus (Rodentia: Cricetidae): An overlooked reservoir of tick‐borne pathogens in the Midwest, USA?

Mice belonging to the genus Peromyscus are one of the most important reservoirs of tick‐borne pathogens in the United States. However, the composition and abundance of Peromyscus species may vary geographically. The woodland deer mouse, Peromyscus maniculatus gracilis, is often abundant in the northern counties of Minnesota, Wisconsin, and Michigan. In these states, multiple pathogens transmitted by the blacklegged tick, Ixodes scapularis , are endemic. In comparison to the well‐studied white‐footed mouse, Peromyscus leucopus , little is known about the importance of P. maniculatus in maintaining natural cycles of tick‐borne pathogens. We conducted small mammal trapping in north‐central Wisconsin and compared the modified reservoir potential of P. maniculatus to P . leucopus . Based on mixed‐model regression analysis, individual P . maniculatus were 2.07 (1.07–4.01) times more likely to be infected with Borrelia burgdorferi compared with P. leucopus . We report the first detection of three emerging tick‐borne pathogens ( Babesia microti , Borrelia mayonii, and Ehrlichia muris eauclairensis ) in P. maniculatus . Additionally, P. maniculatus infected with Ba. microti were 4.8 (2.74–8.50) times more likely to be concurrently infected with Bo. burgdorferi compared with P. leucopus . While we found individual P. leucopus to be more infested with both larval and nymphal I. scapularis , P. maniculatus was the more abundant species. As a result, P. maniculatus had a higher modified reservoir potential in our study area and was likely responsible for feeding and infecting more ticks with pathogens than P. leucopus . Overall, our results illustrate that P. maniculatus is an important reservoir in areas of the Midwest, where it occurs in high abundance.