Geographic distribution of white-tailed deer with ticks and antibodies to Borrelia burgdorferi in Connecticut.

Ticks and blood specimens were collected from white-tailed deer (Odocoileus virginianus) in Connecticut and analyzed to identify foci for Lyme borreliosis. Males and females of Ixodes scapularis, the chief vector of Borrelia burgdorferi, were collected from deer in five of eight counties during 1989-1991. Analysis by indirect fluorescent antibody (IFA) staining of midgut tissues showed that prevalence of infection was highest (9.5% of 367 ticks) in south central and southeastern Connecticut. Infected I. scapularis also were collected from southwestern regions of the state (12.1% of 99 ticks), but prevalence of infection in northern counties was considerably lower (0.8% of 124 ticks). Deer sera, obtained in 1980 and 1989-1991, were analyzed by an enzyme-linked immunosorbent assay or by IFA staining methods. Antibodies to B. burgdorferi were detected in sera collected from all eight counties in Connecticut. Deer had been infected by this spirochete in at least 50 towns, 17 (34%) of which are in south central and southeastern parts of the state. Borrelia burgdorferi is widely distributed in I. scapularis populations in Connecticut.