Potential role of native and exotic deer and their associated ticks (Acari: Ixodidae) in the ecology of Lyme disease in California, USA.

The relationship of native Columbian Black-tailed Deer, two species of exotic deer (Axis and Fallow), and their ticks to the Lyme disease spirochete, Borrelia burgdorferi, was studied in coastal and inland areas of northern California, USA. Spirochetemias were detected in 27% of Black-tailed Deer, 50% of Axis Deer, and 56% of Fallow Deer collected in late fall and winter. Antibody prevalence was 38% in Black-tailed Deer, 24% in Fallow Deer, and 6% in Axis Deer. One to 3 tick species were collected from each species of deer, and 2 tick species were flagged from vegetation; of these, only the Western Black-legged Tick, Ixodes pacificus, was found to contain spirochetes. These findings suggest that all 3 deer species may be important hosts of spirochetes, possibly B. burgdorferi, and reconfirm that I. pacificus is the primary vector of the latter in California.