ORIGINAL ARTICLE Juvenile Dogs as Potential Sentinels for West Nile Virus Surveillance M. P. Resnick 1 , P. Grunenwald 2 , D. Blackmar 2 , C. Hailey 2 , R. Bueno 2 and K. O. Murray 1 1 Center for Infectious Diseases, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX, USA 2 Harris County Public Health and Environmental Services, Houston, TX, USA Impacts • West Nile virus disease (WNV) is an important emerging vector-borne disease, with surveillance being the key in monitoring areas for virus activity. • WNV seroconversion in immunologically naı ¨ve juvenile dogs was detected 6 weeks prior to the first reported human case in Houston, and peak point prevalence over the surveillance period was 47%. • Juvenile dogs can serve as effective sentinels for WNV surveillance. Introduction West Nile virus (WNV) surveillance in Houston is focused primarily on identifying infections in dead birds and mosquitoes (Lillibridge et al., 2004). Positive findings are critical for alerting public health officials to geo- graphic areas where humans could be at risk of infection. Dogs have high rates of WNV seroconversion (Lillibridge et al.,2004; Kile et al., 2005) but do not typically develop clinical disease (Austgen et al., 2004). We conducted this study to determine whether immunologically naı ¨ve juvenile dogs could be suitable sentinels for WNV surveillance. Materials and Methods We conducted a prospective convenience sampling of young (6 to 28 weeks of age) dogs being housed at an animal control facility in Houston, TX. Generally, dogs were not kept at the facility longer than 3–5 days, so a new population was available every week. All puppies available at the time of collection were sampled. The animals’ age was estimated by a licensed veterinarian by conducting a physical examination and verifying tooth development. Blood samples were collected weekly during the 2005 WNV transmission season (end of May to end of October) and tested for anti-WNV IgM and IgG antibodies using enzyme-linked immunosorbent assays (ELISA) (Wang et al., 2002). As the samples were only obtained from animals born in 2005, both IgM- and IgG-positive dogs represented seroconversion during the 2005 transmission season, and incidence of infection was estimated by the weekly point prevalence. Data were entered in Microsoft Excel. The point preva- lence was calculated by dividing the positive samples by the number of samples collected each week. Using stata Keywords: West Nile virus; surveillance; canines; seroconversion; sentinels; enzyme-linked immunosorbant assay Correspondence: K. O. Murray, D.V.M., Ph.D., Assistant Professor, Epidemiology, 1200 Herman Pressler, Rm 338, Houston, TX 77030, USA. Tel.: (713) 500-9358; Fax: (713) 500-9359; E-mail: kristy.o.murray@uth.tmc.edu Received for publication October 30, 2007 doi: 10.1111/j.1863-2378.2008.01116.x Summary We conducted a study to determine whether juvenile stray dogs could be senti- nels for West Nile virus (WNV) surveillance. Seroconversion was detected 6 weeks before the first reported human case. Our findings provide evidence that dogs could be useful sentinels for monitoring areas for evidence of WNV during transmission seasons. Zoonoses and Public Health ª 2008 The Authors Journal compilation ª 2008 Blackwell Verlag • Zoonoses Public Health. 1