Excerpt:

This study was undertaken to determine which rodent species serve
as primary reservoirs for the Lyme disease spirochete Borrelia
burgdorferi in commonly occurring woodland types in inland areas
of northwestern California, and to examine whether chaparral or
grassland serve as source habitats for dispersal of B.
burgdorferi- or B. bissettii-infected rodents into adjacent
woodlands. The western gray squirrel (Sciurus griseus) was
commonly infected with B.
burgdorferi in oak woodlands, whereas examination of 30
dusky-footed woodrats (Neotoma fuscipes) and 280 Peromyscus spp.
mice from 13 widely spaced Mendocino County woodlands during 2002
and 2003 yielded only one infected woodrat and one infected deer
mouse (P. maniculatus). These data suggest that western gray
squirrels account for the majority of production by rodents of
fed Ixodes pacificus larvae infected with B. burgdorferi in the
woodlands sampled.