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  • Rocky Mountain Spotted Fever (RMSF) is one of the deadliest tickborne diseases in the Americas.
  • It caused by a bacteria, Rickettsia rickettsii, that is spread through the bite of an infected tick (the American dog tick (Dermatocentor variabilis), Rocky Mountain wood tick (Dermatocenter variabilis) and in parts of the southwestern United States, the brown dog tick (Rhipicephalus sanguineus).
  • Most of the cases are reported from North Carolina, Tennessee, Missouri, Arkansas, and Oklahoma, however vector transmission of RMSF has also been identified in Arizona.
  • RMSF can rapidly be fatal if not treated promptly. Doxycycline is the recommended antibiotic treatment for RMSF in all ages.

Rocky Mountain Spotted Fever is reportable in Orange County within seven (7) calendar days of identification. To report a case, health care providers/facilities should call OCHCA Epidemiology at 714-834-8180, fax reports to 714-560-4050, or mail to P.O. Box 6128, Santa Ana, CA 92706-0128. Zero to two (0-2) cases of RMSF were reported in Orange County each year between 2013 and 2017; none were locally acquired.


Healthcare Professionals


For more information, see the Centers for Disease Control (CDC) website

Last reviewed December 21, 2018