MB is an employee of IDEXX Laboratories, Inc. vertebrates on which immature ticks feed but that do not serve as qualified reservoirs for contamination in dogs and compare the estimated canine contamination risk to human case reports in the same region. Methods The study Calcium D-Panthotenate area (Fig. ?(Fig.1)1) focused on the New York City Metropolitan Statistical Area (NYC MSA) and included a total of 30 contiguous counties in New York (NY, = 13), New Jersey (NJ, = 13), Connecticut (CT, = 3), and Pennsylvania (PA, = 1). Counties and their corresponding two-letter abbreviations are provided in Additional file 1: Table S1. This region, referred to as the New York-Newark-Bridgeport Metropolitan Statistical Area, is usually highly interconnected and had a human population of more than 20 million by 2014 Census. When surrounding counties were also included, the entire population totaled approximately 22 million [29]. The region was selected for detailed analysis based on a number Calcium D-Panthotenate of factors, namely, large population, ample available data from testing dogs, diverse population density, and diverse environmental conditions. The region includes urban centers in New York City with high development, transitional counties with intermediate habitat types, and exurban, outer counties, that contain larger rural or forested areas. This relatively high diversity of social and environmental factors between contiguous counties allowed us to explore potential risk factors in a region where active transmission is known to occur to both people and dogs. Open in a separate window Fig. 1 Percent positive canine assessments for antibody to by county in the New York City Metropolitan Statistical Area. Counties are labeled with 2 letter abbreviations (full names provided in Additional file 1: Table S1) and were coded as follows: 0C5% (light blue), 6C10% (blue), 11C20% (dark blue), and 20% (very dark blue) A national veterinary reporting system created and supported by IDEXX Laboratories, Inc. (Westbrook, ME, USA) provided data by county and year to allow generation of percent positive canine test results for antibodies to to submit their results. To insure anonymity of both patients and practices, all test results were grouped by location (county, state) of the reporting veterinary practices and then summed and sorted [3, 4]. Data from testing 234,633 dogs for the last decade (2001C2010) in the study area were included in the present study. All qualitative testing was conducted using in-clinic SNAP?3Dx? Test kit or SNAP?4Dx? Test kit (IDEXX Laboratories, Westbrook, ME, USA), in-clinic ELISA assays that simultaneously detect antigen and canine antibodies to and AIGF results were used in the present study. These in-clinic assays employ a C6 peptide-based system to detect antibodies Calcium D-Panthotenate to and have been documented to have a specificity of 99.6% on field samples [24] and a sensitivity of 94.4% when compared to a combination of immunofluorescence assay (IFA) and Western blot (WB) [30]. In addition, the test used does not react to antibodies generated by vaccination [31, 32]. An initial categorical analysis was performed to determine if differences in percent positive assessments results between counties were associated with general demographic and habitat types. Variables evaluated in the initial analysis included: population density [33, 34], median household income Calcium D-Panthotenate [34], percent forested area [35], percent canine samples positive for antibody to and annual number of human cases per 100,000 people as reported by the CDC between 2002 and 2006 [36]. All data were summarized and analyzed at the county level. For regression, more specific environmental variables were added including precipitation and maximum and minimum temperature for the month of November. This month was selected to represent a key time in the life-cycle of 0.05). Variables considered were: percent positive canine assessments (0C10%, 10C20%, 20%), percent forested area ( 25%, 25C50%, 50%), population density ( 2500, 2500C7500, 7500 person/sq mi), human case reports of Lyme disease per 100,000 people ( 10, 10C100, 100), and median household income ( $70,000 USD, $70,000 USD). Variables that differed significantly were designated by different letters; variables that did not differ significantly shared the same letter designation. Regression analyses using more specific environmental data were performed (StatPlus v4, AnalystSoft, Alexandria, VA, USA), with significance assessed at 5% ( 0.05). An initial simple regression was performed to compare either percent positive canine assessments or human case reports to each variable. All variables significant by simple regression were analyzed pairwise using a Pearsons correlation test; the significance of any two variables with a correlation value over 0.9 (OO 0.9) was assessed and variables that did not contribute significantly to help expand analysis were removed [39], multiple backward-stepwise regression then.