title: Ehrlichia ewingii infection and exposure rates in dogs from the southcentral United States.
abstract: We used PCR and a novel serologic assay to determine infection and exposure rates to Ehrlichia ewingii in dogs from an area of northeast Oklahoma and northwest Arkansas where Amblyomma americanum ticks are abundant. Of 143 dogs assayed, 13 (9.1%) harbored E. ewingii by PCR and 64 (44.8%) had antibodies to E. ewingii detected using a peptide-based microtiter plate ELISA. Dogs were more likely (P=0.001) to be positive by PCR if sampled in August (30.8%) but no association was found between seropositive status and month of collection of sample (P>0.05). Additional testing revealed PCR evidence of Ehrlichia chaffeensis (4/143; 2.8%) and Anaplasma platys (5/143; 3.5%) as well as antibodies reactive to E. chaffeensis (25/143; 17.5%), Ehrlichia canis (2/143; 1.4%), and Anaplasma spp. (8/143; 5.6%). Testing of another 200 dogs from the area revealed additional PCR and/or serologic evidence of E. ewingii, E. canis, E. chaffeensis, and A. platys. None of the 343 dogs evaluated had evidence of Borrelia burgdorferi exposure. These data support the interpretation that E. ewingii may be the primary agent of canine ehrlichiosis in this region, and suggest that diagnostic evaluation of dogs suspected to have a tick-borne disease should include assays targeting this organism.
authors.affiliation: Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA. susan.little@okstate.edu
authors.forename: Susan E
authors.initials: SE
authors.lastname: Little
authors.forename: Thomas P
authors.initials: TP
authors.lastname: O'Connor
authors.forename: Julie
authors.initials: J
authors.lastname: Hempstead
authors.forename: Jill
authors.initials: J
authors.lastname: Saucier
authors.forename: Mason V
authors.initials: MV
authors.lastname: Reichard
authors.forename: Katrina
authors.initials: K
authors.lastname: Meinkoth
authors.forename: James H
authors.initials: JH
authors.lastname: Meinkoth
authors.forename: Blaine
authors.initials: B
authors.lastname: Andrews
authors.forename: Steve
authors.initials: S
authors.lastname: Ullom
authors.forename: Sidney A
authors.initials: SA
authors.lastname: Ewing
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Chandrashekar
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001131:Arkansas / Q000453:epidemiology; D004283:Dog Diseases / Q000453:epidemiology*; D004285:Dogs; D004536:Ehrlichia / Q000502:physiology*; D016873:Ehrlichiosis / Q000453:epidemiology / Q000662:veterinary*; D009825:Oklahoma / Q000453:epidemiology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D015995:Prevalence; D017282:Tick-Borne Diseases / Q000453:epidemiology / Q000662:veterinary*
chemical_list: D000907:Antibodies, Bacterial