Great story by the Washington Post (reprinted in the Bangor Daily News here) about why the white-footed mouse is such a prolific carrier of Lyme disease:
What makes the mice such excellent carriers?
Lax grooming habits. Passive immune systems. Endless offspring that can potentially carry on disease, scientists say.
“For reasons we don’t understand, mice are what we call extremely tolerant of both tick infestations and Lyme bacteria in their bodies,” said Ostfeld. “The mice just aren’t fastidious. They just don’t really care about being bitten by lots of ticks.”
In addition, white-footed mice have bloodstreams that Ostfeld calls “a breeding ground for all kinds of infectious agents,” including pathogens that cause babesiosis and anaplasmosis, other tick-borne diseases.