title: Development of antibodies to and PCR detection of Ehrlichia spp. in dogs following natural tick exposure.
abstract: 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 (SNAP® 4Dx® and SNAP® 4Dx® 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, GMTMAX=548.7) and E. chaffeensis (10/10, maximum inverse titer=1024-32,768, GMTMAX=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.
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA.
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Starkey
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA.
authors.forename: Anne W
authors.initials: AW
authors.lastname: Barrett
authors.affiliation: IDEXX Laboratories, Inc., Westbrook, ME, USA.
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Chandrashekar
authors.affiliation: IDEXX Laboratories, Inc., Westbrook, ME, USA.
authors.forename: Brett A
authors.initials: BA
authors.lastname: Stillman
authors.affiliation: IDEXX Laboratories, Inc., Westbrook, ME, USA.
authors.forename: Phyllis
authors.initials: P
authors.lastname: Tyrrell
authors.affiliation: IDEXX Laboratories, Inc., Westbrook, ME, USA.
authors.forename: Brendon
authors.initials: B
authors.lastname: Thatcher
authors.affiliation: IDEXX Laboratories, Inc., Westbrook, ME, USA.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Beall
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA.
authors.forename: Jeff M
authors.initials: JM
authors.lastname: Gruntmeir
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA.
authors.forename: James H
authors.initials: JH
authors.lastname: Meinkoth
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, 250 McElroy Hall, Stillwater, OK 74078, USA. Electronic address: susan.little@okstate.edu.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Little
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001483:Base Sequence; D001772:Blood Cell Count / Q000662:veterinary; D004283:Dog Diseases / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology*; D004285:Dogs / Q000469:parasitology*; D004536:Ehrlichia / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D016873:Ehrlichiosis / Q000453:epidemiology / Q000276:immunology / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D008969:Molecular Sequence Data; D009825:Oklahoma / Q000453:epidemiology; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D018571:Sentinel Surveillance / Q000662:veterinary; D017422:Sequence Analysis, DNA; D013987:Ticks / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial
keywords: Dog; Ehrlichia chaffeensis; Ehrlichia ewingii; Ehrlichiosis; Ticks