Vector-borne infections in dogs occur throughout the US; however, temporal trends in prevalence for most infections have been poorly described. The objective of this study was to evaluate the seroprevalence of Anaplasma spp., Babesia canis, Bartonella henselae, Bartonella vinsonii subsp. berkhoffii, Borrelia burgdorferi, Dirofilaria immitis, Ehrlichia canis, and Rickettsia rickettsii in dog blood samples submitted to the Vector-Borne Disease Diagnostic Laboratory at NCSU from January 2004 to December 2007. From the laboratory database, 9386 accessions (2200 dogs in 2004, 2386 dogs in 2005, 2435 dogs in 2006, and 2365 in 2007), for which serological results were available for at least three test organisms, were selected for analyses. Indirect immunofluorescent assays (IFA) with cut-offs of 1:64 were used to detect exposure to B. canis, B. henselae, B. v. berkhoffii, E. canis and R. rickettsii. The Snap® 4Dx® was used to detect exposure to Anaplasma spp., B. burgdorferi, D. immitis and E. canis. Gender information was available only for years 2006 and 2007, with 2382 males (50.1%) and 2371 females (49.9%). 9021 samples (96.1%) were submitted from 47 states, the District of Columbia, and from 2 territories (PR and VI), with Southern and Midwestern regions overrepresented (70.6% and 17.8% of US samples, respectively). 365 samples (3.9%) were submitted from Canada. Overall seroprevalences are presented in Table 1. Regionally, Babesia canis seroprevalence increased in 2005 and decreased in 2007 in southern states. A significant decrease in B. henselae seroprevalence occurred from 2004 to 2005, especially in northeastern and southern states of the US, and in Canada. A significant increase in B. v. berkhoffii seroprevalence occurred from 2004 to 2007, especially in southern states. Ehrlichia canis seroprevalences decreased from 2004 to 2007, especially in western and southern states. There was a significant increase in R. rickettsii seroprevalence from 2004 to 2007, especially in Midwestern and southern states. Monitoring vector-borne exposures in pets over years is critical for establishing trends and future actions, not only in veterinary, but also in human medicine. Trends may reflect fluctuations in vector biology or shifts in awareness on the part of medical care givers.

Table 1. Seroprevalences.