Bartonella species were isolated from 49% of 128 cattle from California and
Oklahoma, 90% of 42 mule deer from California, and 15% of 100 elk from Cal
ifornia and Oregon. Isolates from all 63 cattle, 14 deer, and 1 elk had the
same polymerase chain reaction/restriction fragment length polymorphism pr
ofiles. Our findings indicate potential for inter- and intraspecies transmi
ssion among ruminants, as well as risk that these Bartonella spp, could act
as zoonotic agents.