Short Communication Development of antibodies to and PCR detection of Ehrlichia spp. in dogs following natural tick exposure Lindsay A. Starkey a , Anne W. Barrett a , Ramaswamy Chandrashekar b , Brett A. Stillman b , Phyllis Tyrrell b , Brendon Thatcher b , Melissa J. Beall b , Jeff M. Gruntmeir a , James H. Meinkoth a , Susan E. Little a, * a Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA b IDEXX Laboratories, Inc., Westbrook, ME, USA 1. Introduction Dogs are known to be susceptible to infection with several different Ehrlichia spp. Ehrlichia canis, the causative agent of canine monocytic ehrlichiosis, is considered the most pathogenic; in some cases, fatalities result. Ehrlichia ewingii has the capacity to set up long-term infections in dogs and may induce polyarthritis (Little, 2010). Other Ehrlichia spp., including E. chaffeensis, E. muris, and Panola Mountain Ehrlichia (PME), have also been reported from dogs (Little et al., 2010; Hegarty et al., 2012; Qurollo et al., 2013). A number of Ehrlichia spp. also have been reported to cause disease in humans, although E. chaffeensis is considered to be the most common and clinically severe (Nicholson et al., 2010). Amblyomma americanum is responsible for transmis- sion of E. chaffeensis, E. ewingii, and PME (Anziani et al., 1990; Ewing et al., 1995; Yabsley et al., 2008) in the Veterinary Microbiology xxx (2014) xxx–xxx * Corresponding author. Tel.: +1 405 744 8523; fax: +1 405 744 5275. E-mail address: susan.little@okstate.edu (S.E. Little). A R T I C L E I N F O Article history: Received 31 March 2014 Received in revised form 30 July 2014 Accepted 1 August 2014 Keywords: Dog Ehrlichia chaffeensis Ehrlichia ewingii Ehrlichiosis Ticks A B S T R A C T Dogs exposed to ticks in the southern US may become infected with multiple species of Ehrlichia. To better define infection risk, blood samples collected from 10 dogs infested with ticks via a natural infestation model were evaluated by blood smear examination, PCR, patient-side ELISAs (SNAP1 4Dx1 and SNAP1 4Dx1 Plus), IFA, and peptide based ELISA for evidence of infection with Ehrlichia canis, E. chaffeensis, and/or E. ewingii. Although morulae were rarely identified in blood smears, every dog (10/10) became infected with Ehrlichia spp. as evidenced by nested PCR detection of E. chaffeensis (7/10) and E. ewingii DNA (10/10); real-time PCR detection of E. chaffeensis (0/10) and E. ewingii (9/10); seroconversion on two different patient-side ELISAs (4/10 or 10/10); seroconversion on IFA to E. canis (10/10, maximum inverse titer = 128–4096, GMT MAX = 548.7) and E. chaffeensis (10/10, maximum inverse titer = 1024–32,768, GMT MAX = 4096); and seroconversion on peptide specific ELISA to E. chaffeensis VLPT (7/10) and E. ewingii p28 (9/10). Rickettsemia with E. chaffeensis and E. ewingii, as determined by nested PCR, persisted in dogs for an average of 3.2 or 30.5 days, respectively. Ehrlichia canis was not detected in any dog by any method, and no dogs developed signs of clinical disease. Our data suggest that in areas where ticks are common, dogs are at high risk of infection with Ehrlichia spp., particularly E. ewingii and E. chaffeensis, and can serve as a sentinel for monitoring for the presence of these zoonotic pathogens. ß 2014 Elsevier B.V. All rights reserved. G Model VETMIC-6702; No. of Pages 6 Please cite this article in press as: Starkey, L.A., et al., Development of antibodies to and PCR detection of Ehrlichia spp. in dogs following natural tick exposure. Vet. Microbiol. (2014), http://dx.doi.org/10.1016/j.vetmic.2014.08.006 Contents lists available at ScienceDirect Veterinary Microbiology jo u rn al ho m epag e: ww w.els evier.c o m/lo cat e/vetmic http://dx.doi.org/10.1016/j.vetmic.2014.08.006 0378-1135/ß 2014 Elsevier B.V. All rights reserved.