Rocky Mountain Spotted Fever



Rickettsial invasion of small blood vessels:
  • Causes direct vascular damage
  • Superimposed additional vascular damage/vasculitis due to immunologic phenomena


  • Acute infection by Rickettsia rickettsii via tick vector:
    • Dermacentor andersoni (wood tick) in the western states
    • Dermacentor variabilis (dog tick) in the eastern states
  • Reported in all states; 1/2 of cases occur in 5 states (NC, SC, TN, OK, AR), as well as parts of Central America and South America
  • More common April–September, but can occur any month
  • More common in males and in individuals 40–64 yr of age

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