Southern tick-associated rash illness is a Lyme-like syndrome that occurs in the 
southern states. Borrelia lonestari, which has been suggested as a possible 
causative agent of southern tick-associated rash illness, naturally infects 
white-tailed deer (WTD; Odocoileus virginianus) and is transmitted by the lone 
star tick (Amblyomma americanum). To better understand the prevalence and 
distribution of Borrelia exposure among WTD, we tested WTD from 21 eastern 
states for antibodies reactive to B. lonestari using an indirect 
immunofluorescent antibody assay and Borrelia burgdorferi using the IDEXX SNAP 
4Dx test. A total of 107/714 (15%) had antibodies reactive to B. lonestari, and 
prevalence of antibodies was higher in deer from southern states (17.5%) than in 
deer from northern states (9.2%). Using the SNAP 4DX test, we found that 73/723 
(10%) were positive for B. burgdorferi, and significantly more northern deer 
(23.9%) were positive compared with southern deer (3.8%). Our data demonstrate 
that WTD are exposed to both Borrelia species, but antibody prevalence for 
exposure to the two species differs regionally and distributions correlate with 
the presence of Ixodes scapularis and A. americanum ticks.