title: Risk factors for fatal outcome from rocky mountain spotted Fever in a highly endemic area-Arizona, 2002-2011.
abstract: BACKGROUND
  Rocky Mountain spotted fever (RMSF) is a disease that now causes significant morbidity and mortality on several American Indian reservations in Arizona. Although the disease is treatable, reported RMSF case fatality rates from this region are high (7%) compared to the rest of the nation (<1%), suggesting a need to identify clinical points for intervention.
  
  
  METHODS
  The first 205 cases from this region were reviewed and fatal RMSF cases were compared to nonfatal cases to determine clinical risk factors for fatal outcome.
  
  
  RESULTS
  Doxycycline was initiated significantly later in fatal cases (median, day 7) than nonfatal cases (median, day 3), although both groups of case patients presented for care early (median, day 2). Multiple factors increased the risk of doxycycline delay and fatal outcome, such as early symptoms of nausea and diarrhea, history of alcoholism or chronic lung disease, and abnormal laboratory results such as elevated liver aminotransferases. Rash, history of tick bite, thrombocytopenia, and hyponatremia were often absent at initial presentation.
  
  
  CONCLUSIONS
  Earlier treatment with doxycycline can decrease morbidity and mortality from RMSF in this region. Recognition of risk factors associated with doxycycline delay and fatal outcome, such as early gastrointestinal symptoms and a history of alcoholism or chronic lung disease, may be useful in guiding early treatment decisions. Healthcare providers should have a low threshold for initiating doxycycline whenever treating febrile or potentially septic patients from tribal lands in Arizona, even if an alternative diagnosis seems more likely and classic findings of RMSF are absent.
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.
authors.forename: Joanna J
authors.initials: JJ
authors.lastname: Regan
authors.affiliation: Indian Health Service Hospital, Arizona.
authors.forename: Marc S
authors.initials: MS
authors.lastname: Traeger
authors.affiliation: Indian Health Service Hospital, Arizona.
authors.forename: Dwight
authors.initials: D
authors.lastname: Humpherys
authors.affiliation: Indian Health Service Hospital, Arizona.
authors.forename: Dianna L
authors.initials: DL
authors.lastname: Mahoney
authors.affiliation: Indian Health Service Hospital, Arizona.
authors.forename: Michelle
authors.initials: M
authors.lastname: Martinez
authors.affiliation: Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathogenicity, NCEZID.
authors.forename: Ginny L
authors.initials: GL
authors.lastname: Emerson
authors.affiliation: Epidemic Intelligence Service, Division of Applied Public Health Training, Epidemiology Program Office, CDC, Atlanta, Georgia.
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Tack
authors.affiliation: Bacterial Diseases Branch, Division of Vector-Borne Diseases, NCEZID, CDC, Fort Collins, Colorado.
authors.forename: Aimee
authors.initials: A
authors.lastname: Geissler
authors.affiliation: Epidemic Intelligence Service, Division of Applied Public Health Training, Epidemiology Program Office, CDC, Atlanta, Georgia.
authors.forename: Seema
authors.initials: S
authors.lastname: Yasmin
authors.affiliation: Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh.
authors.forename: Regina
authors.initials: R
authors.lastname: Lawson
authors.affiliation: Department of Health and Human Services, Community B.
authors.forename: Velda
authors.initials: V
authors.lastname: Williams
authors.affiliation: Division of Health Programs, Community A.
authors.forename: Charlene
authors.initials: C
authors.lastname: Hamilton
authors.affiliation: Bureau of Epidemiology and Disease Control, Division of Public Health Services, Arizona Department of Health Services, Phoenix.
authors.forename: Craig
authors.initials: C
authors.lastname: Levy
authors.affiliation: Bureau of Epidemiology and Disease Control, Division of Public Health Services, Arizona Department of Health Services, Phoenix.
authors.forename: Ken
authors.initials: K
authors.lastname: Komatsu
authors.affiliation: Indian Health Service Hospital, Arizona.
authors.forename: David A
authors.initials: DA
authors.lastname: Yost
authors.affiliation: Rickettsial Zoonoses Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia.
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: McQuiston
mesh_terms: D000818:Animals; D019353:Endemic Diseases; D005260:Female; D006801:Humans; D008297:Male; D012373:Rocky Mountain Spotted Fever / Q000453:epidemiology* / Q000473:pathology*
keywords: American Indians; Rhipicephalus sanguineus; Rocky Mountain spotted fever; fatalities; tick-borne