The dog as a sentinel for human infection: prevalence of Borrelia burgdorferi C6 antibodies in dogs from southeastern and mid-Atlantic states.

Lyme disease is the most frequently reported human vector-associated disease in the United States. Infection occurs after the bite of an Ixodid tick that is infected with Borrelia burgdorferi. Dogs have often been reported to serve as effective sentinel animals to assess the risk of human B. burgdorferi infection. Based on published data of human Lyme disease case numbers and our clinical impressions, we hypothesized that canine exposure to B. burgdorferi would be lower in North Carolina when compared to the exposure in Virginia, Maryland, and Pennsylvania. To address this hypothesis, we evaluated B. burgdorferi exposure status utilizing a specific and sensitive C6 peptide-based enzyme-linked immunosorbent assay. Our convenience sample included 1,666 canine serum samples submitted to the Vector Borne Disease Diagnostic Laboratory from North Carolina (n = 987), Virginia (n = 472), Maryland (n = 167), and Pennsylvania (n = 40). Comparisons among states were made using the Chi-square test or the Fisher's exact test; p-values were adjusted for multiple comparisons using the Bonferroni correction. A Chi-square test for trend was used to determine if there was an increase in the frequency of seroreactors associated with the geographical origin of the samples. The proportion of seroreactive dogs in North Carolina was markedly lower (p < 0.008) than that observed in dogs from Virginia, Maryland, and Pennsylvania. These results support the hypothesis that B. burgdorferi transmission seems to occur infrequently in North Carolina dogs as compared to dogs residing in other southeastern and mid-Atlantic states. Furthermore, they support the utility of dogs as a sentinel to characterize the risk of B. burgdorferi transmission to humans in a defined geographical location.