Multihost Bartonella parasites display covert host specificity even when transmitted by generalist vectors

Many parasites infect multiple sympatric host species, and there is a general assumption that parasite transmission between co-occurring host species is commonplace. Such between-species transmission could be key to parasite persistence within a disease reservoir and is consequently an emerging focus for disease control.
However, while a growing body of theory indicates the potential importance of between-species transmission for parasite persistence, conclusive empirical evidence from natural communities is lacking, and the assumption that between-species transmission is inevitable may therefore be wrong.
We investigated the occurrence of between-species transmission in a well-studied multihost parasite system. We identified the flea-borne Bartonella parasites infecting sympatric populations of Apodemus sylvaticus (wood mice) and Myodes glareolus (bank voles) in the UK and confirmed that several Bartonella species infect both rodent species. However, counter to previous knowledge, ge...