title: Persistent Ehrlichia ewingii infection in dogs after natural tick infestation.
abstract: BACKGROUND
  Ehrlichia ewingii, which causes disease in dogs and people, is the most common Ehrlichia spp. infecting dogs in the United States, but little is known about how long E. ewingii infection persists in dogs.
  
  
  OBJECTIVE
  To evaluate the persistence of natural infection with E. ewingii in dogs.
  
  
  METHODS
  Four Class A Beagles; no previous exposure to ticks or tick-borne infectious agents.
  
  
  METHODS
  Dogs were exposed to ticks by weekly walks through tick habitat in north central Oklahoma; dogs positive for infection with Ehrlichia spp. by sequence-confirmed PCR and peptide-specific serology were evaluated for 733 days (D). Whole blood was collected once weekly for PCR, and serum was collected once monthly for detection of antibodies to Ehrlichia canis (peptide p16), Ehrlichia chaffeensis (indirect fluorescence antibody [IFA] and variable-length PCR target [VLPT]), and E. ewingii (peptide p28).
  
  
  RESULTS
  All dogs (4/4) became infected with Ehrlichia spp. as evidenced by seroconversion on IFA to E. chaffeensis (4/4); PCR detection of E. ewingii (4/4) and E. chaffeensis (2/4) DNA using both nested and real-time assays; and presence of specific antibodies to E. ewingii (4/4) and E. chaffeensis (2/4). Infection with E. chaffeensis was not detected after D55. Intermittent E. ewingii rickettsemia persisted in 3 of 4 dogs for as long as 733 days.
  
  
  CONCLUSIONS
  Our data demonstrate that dogs infected with E. ewingii from tick feeding are capable of maintaining infection with this pathogen long-term, and may serve as a reservoir host for the maintenance of E. ewingii in nature.
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK.
authors.forename: L A
authors.initials: LA
authors.lastname: Starkey
authors.forename: A W
authors.initials: AW
authors.lastname: Barrett
authors.forename: M J
authors.initials: MJ
authors.lastname: Beall
authors.forename: R
authors.initials: R
authors.lastname: Chandrashekar
authors.forename: B
authors.initials: B
authors.lastname: Thatcher
authors.forename: P
authors.initials: P
authors.lastname: Tyrrell
authors.forename: S E
authors.initials: SE
authors.lastname: Little
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial; D004283:Dog Diseases / Q000097:blood / Q000209:etiology / Q000382:microbiology*; D004285:Dogs; D004536:Ehrlichia / Q000276:immunology*; D018469:Ehrlichia chaffeensis / Q000276:immunology; D016873:Ehrlichiosis / Q000382:microbiology / Q000662:veterinary*; D019084:Fluorescent Antibody Technique, Indirect; D016133:Polymerase Chain Reaction / Q000379:methods; D013984:Tick Infestations / Q000097:blood / Q000150:complications / Q000662:veterinary*
chemical_list: D000907:Antibodies, Bacterial
keywords: Amblyomma americanum; Granulocytic ehrlichiosis; Reservoir host