title: The expanding spectrum of eschar-associated rickettsioses in the United States.
abstract: BACKGROUND
  Until recently, Rickettsia rickettsii was the only substantiated cause of tick-borne spotted fever group (SFG) rickettsiosis in humans in the United States. Rickettsia parkeri, originally thought to be nonpathogenic in humans, was recently proved to be another cause of tick-borne SFG rickettsiosis.
  
  
  METHODS
  We report 3 cases of SFG rickettsiosis and discuss the epidemiology, clinical presentation, histopathologic features, and laboratory findings that support confirmed or probable diagnoses of R parkeri infection and describe the expanding list of eschar-associated SFG rickettsioses recognized in US patients.
  
  
  CONCLUSIONS
  The SFG rickettsioses share many clinical manifestations and extensive antigenic cross-reactivity that may hamper specific confirmation of the causative agent.
authors.affiliation: Dermatology Service, San Antonio Military Medical Center, 2200 Bergquist Dr, Ste 1, Lackland AFB, TX 78236-9908, USA. chad.cragun@us.army.mil
authors.forename: W Chad
authors.initials: WC
authors.lastname: Cragun
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Bartlett
authors.forename: Michael W
authors.initials: MW
authors.lastname: Ellis
authors.forename: Aaron Z
authors.initials: AZ
authors.lastname: Hoover
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Tyring
authors.forename: Natalia
authors.initials: N
authors.lastname: Mendoza
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Vento
authors.forename: William L
authors.initials: WL
authors.lastname: Nicholson
authors.forename: Marina E
authors.initials: ME
authors.lastname: Eremeeva
authors.forename: Juan P
authors.initials: JP
authors.lastname: Olano
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Rapini
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Paddock
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D001706:Biopsy; D003937:Diagnosis, Differential; D019353:Endemic Diseases; D006801:Humans; D008297:Male; D008875:Middle Aged; D012284:Rickettsia rickettsii / Q000276:immunology* / Q000302:isolation & purification; D012373:Rocky Mountain Spotted Fever / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology; D012867:Skin / Q000382:microbiology / Q000473:pathology*; D013781:Texas / Q000453:epidemiology
chemical_list: D000907:Antibodies, Bacterial