title: Emergence of a new pathogenic Ehrlichia species, Wisconsin and Minnesota, 2009.
abstract: BACKGROUND
  Ehrlichiosis is a clinically important, emerging zoonosis. Only Ehrlichia chaffeensis and E. ewingii have been thought to cause ehrlichiosis in humans in the United States. Patients with suspected ehrlichiosis routinely undergo testing to ensure proper diagnosis and to ascertain the cause.
  
  
  METHODS
  We used molecular methods, culturing, and serologic testing to diagnose and ascertain the cause of cases of ehrlichiosis.
  
  
  RESULTS
  On testing, four cases of ehrlichiosis in Minnesota or Wisconsin were found not to be from E. chaffeensis or E. ewingii and instead to be caused by a newly discovered ehrlichia species. All patients had fever, malaise, headache, and lymphopenia; three had thrombocytopenia; and two had elevated liver-enzyme levels. All recovered after receiving doxycycline treatment. At least 17 of 697 Ixodes scapularis ticks collected in Minnesota or Wisconsin were positive for the same ehrlichia species on polymerase-chain-reaction testing. Genetic analyses revealed that this new ehrlichia species is closely related to E. muris.
  
  
  CONCLUSIONS
  We report a new ehrlichia species in Minnesota and Wisconsin and provide supportive clinical, epidemiologic, culture, DNA-sequence, and vector data. Physicians need to be aware of this newly discovered close relative of E. muris to ensure appropriate testing, treatment, and regional surveillance. (Funded by the National Institutes of Health and the Centers for Disease Control and Prevention.).
authors.affiliation: Mayo Clinic, Division of Clinical Microbiology, Hilton 470-B, 200 1st St. SW, Rochester, MN 55905, USA. pritt.bobbi@mayo.edu
authors.forename: Bobbi S
authors.initials: BS
authors.lastname: Pritt
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Sloan
authors.forename: Diep K Hoang
authors.initials: DK
authors.lastname: Johnson
authors.forename: Ulrike G
authors.initials: UG
authors.lastname: Munderloh
authors.forename: Susan M
authors.initials: SM
authors.lastname: Paskewitz
authors.forename: Kristina M
authors.initials: KM
authors.lastname: McElroy
authors.forename: Jevon D
authors.initials: JD
authors.lastname: McFadden
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Binnicker
authors.forename: David F
authors.initials: DF
authors.lastname: Neitzel
authors.forename: Gongping
authors.initials: G
authors.lastname: Liu
authors.forename: William L
authors.initials: WL
authors.lastname: Nicholson
authors.forename: Curtis M
authors.initials: CM
authors.lastname: Nelson
authors.forename: Joni J
authors.initials: JJ
authors.lastname: Franson
authors.forename: Scott A
authors.initials: SA
authors.lastname: Martin
authors.forename: Scott A
authors.initials: SA
authors.lastname: Cunningham
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Steward
authors.forename: Kay
authors.initials: K
authors.lastname: Bogumill
authors.forename: Mary E
authors.initials: ME
authors.lastname: Bjorgaard
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Davis
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: McQuiston
authors.forename: David M
authors.initials: DM
authors.lastname: Warshauer
authors.forename: Mark P
authors.initials: MP
authors.lastname: Wilhelm
authors.forename: Robin
authors.initials: R
authors.lastname: Patel
authors.forename: Vipul A
authors.initials: VA
authors.lastname: Trivedi
authors.forename: Marina E
authors.initials: ME
authors.lastname: Eremeeva
mesh_terms: D000818:Animals; D004536:Ehrlichia / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D016873:Ehrlichiosis / Q000382:microbiology*; D005260:Female; D006801:Humans; D018884:Ixodes / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D008910:Minnesota; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D014922:Wisconsin; D055815:Young Adult; D015047:Zoonoses / Q000382:microbiology*