Use of tick surveys and serosurveys to evaluate pet dogs as a sentinel species for emerging Lyme disease

Objective-To evaluate dogs as a sentinel species for emergence of Lyme disease in a region undergoing invasion by Ixodes scapularis. Sample Population-353 serum samples and 78 ticks obtained from dogs brought to 18 veterinary clinics located in the lower peninsula of Michigan from July 15, 2005, through August 15, 2005. Procedures-Serum samples were evaluated for specific antibodies against Borrelia burgdorferi by use of 3 serologic assays. Ticks from dogs were subjected to PCR assays for detection of pathogens. Results-Of 353 serum samples from dogs in 18 counties in 2005, only 2 (0.6%) contained western blot analysis-confirmed antibodies against B burgdorferi. Ten of 13 dogs with I scapularis were from clinics within or immediately adjacent to the known tick invasion zone. Six of 18 / scapularis and 12 of 60 noncompetent vector ticks were infected with B burgdorferi. No ticks were infected with Anaplasma phagocytophilum, and 3 were infected with Babesia spp. Conclusions and Clinical Relevance-Serosurvey in dogs was found to be ineffective in tracking early invasion dynamics of / scapularis in this area. Tick chemoprophylaxis likely reduces serosurvey sensitivity in dogs. Ticks infected with B burgdorferi were more common and widely dispersed than seropositive dogs. In areas of low tick density, use of dogs as a source of ticks is preferable to serosurvey for surveillance of emerging Lyme disease. Impact for Human Medicine-By retaining ticks from dogs for identification and pathogen testing, veterinarians can play an important role in early detection in areas with increasing risk of Lyme disease. (Am J Vet Res 2009;70:49-56)