Rocky Mountain Spotted Fever Fact Sheet

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Rocky Mountain Spotted Fever (RMSF) 

  • ​It is caused by the bacterium known as Rickettsia rickettsii.
  • RMSF cases occur across the United States, but are most commonly reported in North Carolina, Tennessee, Missouri, Arkansas, and Oklahoma.

Rocky Mountain spotted fever is transmitted in nature by the bite of infected ticks.

  • Dermacentor variabilis, also called the American dog tick, is the main transmitter of the infection in Maryland, and the eastern half of the United States.
  • Dermacentor andersoni, called the Rocky Mountain wood tick, can also transmit the bacteria in the upper northwest section of the United States.
  • Rhipicephalus sanguineus, also called the brown dog tick, can also transmit the bacteria in the southwestern United States.

Signs and symptoms

  • Signs and symptoms begin 3-12 days after a tick bite.
  • Illness begins with sudden onset of fever and headache.
  • Rash typically occurs 2-4 days after the onset of fever.  It is highly variable and some people may fail to develop a rash.
  • Other symptoms include nausea/vomiting, abdominal pain, body aches, and swelling around the eyes and on the back of hands.

Diagnosis and treatment

  • RMSF is a rapidly progressive disease and without early administration of treatment, it can be fatal within days.  See your doctor right away if you think you migh have RMSF.
  • There are blood tests that can help diagnose Rocky Mountain spotted fever.
  • Doxycycline is the most effective treatment for RMSF, including for children under 8 years of age.
  • Make sure you inform your doctor of any recent tick bites and of being in any wooded areas.

Keep Ticks Off

  • Ticks are most active from late spring through early fall.
  • Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), paramenthane-diol (PMD), or 2-undecanone to prevent tick bites.  Use as directed.
  • Repellents containing DEET may be used on children over 2 months of age.
  • Treat clothes with permethrin (do not use permethrin directly on skin).
  • Wear long pants and long sleeves to help keep ticks off of skin, and tuck pant legs into socks and shirts into pants to keep ticks on outside of clothing.
  • Wear light colored clothing to spot ticks more easily.
  • Talk to your veterinarian about tick control products for your pets.
  • When enjoying the outdoors, be aware that wooded or brushy areas with tall grass and leaf litter are prime tick habitat.  Walk in the center of the trail.
  • Check yourself, your kids, and your pets daily for ticks when spending time in tick habitat.
  • Bathe or shower as soon as possible after coming indoors (within 2 hours) to wash off ticks.

To Remove Ticks

  • Use fine-tipped tweezers.
  • Grab the tick close to the skin; do not twist or jerk the tick.
  • Gently pull straight up until all parts of the tick are removed.
  • Wash your hands with soap and water or an alcohol-based rub.
  • Clean the site of the tick bite with soap and water or an antiseptic.
  • Do not use petroleum jelly, a hot match, nail polish, or other products to remove ticks.

For more information on tickborne diseases, visit: