THE DISTRIBUTION OF CANINE EXPOSURE TO BORRELIA-BURGDORFERI IN A LYME-DISEASE ENDEMIC AREA

Objectives. A serosurvey of canine exposure to Borrelia burgdorferi, t he causative agent of human Lyme disease, was conducted in Westchester County, New York, to determine the distribution of exposure in an are a endemic for Lyme disease. Methods. A total of 1446 blood samples was collected from resident dogs and tested by modified enzyme-linked imm unosorbent assay. Equivocal samples were further tested by immunoblot. A mean number of 57.8 samples was collected from each of 25 towns and cities. Results. Seroprevalence rates for municipalities ranged from 6.5% to 85.2%. County seroprevalence was 49.2%. There was a significan t difference among the rates for the northern (67.3%), central (45.2%) , and southern (17.3%) regions. Multiple range analysis indicated homo geneity between the southern and central regions and the central and n orthern regions. Conclusions. Canine exposure to B burgdorferi increas es in a south to north gradient within the county. Intensity of exposu re, measured by enzyme-linked immunosorbent assay titers, indicates a similar pattern. The close association between dogs and humans suggest s that human risk of acquiring Lyme disease within Westchester County is equally disparate and is inversely related to the degree of urbaniz ation.