Rocky Mountain Spotted Fever Fact Sheet

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Rocky Mountain Spotted Fever (RMSF) is caused by a bacterium known as Rickettsia rickettsii

You can't catch RMSF from another person—you catch it from a tick bite

It is spread by the bite of the American dog tick. Ticks must be attached to the body for at least 4 to 6 hours before they pass RMSF bacteria to humans. Not every tick bite causes RMSF.


Symptoms appear 3 to 14 days after a tick bite

People with RMSF may have flu-like symptoms, high fever (above 101F), headache, nausea or vomiting, tiredness, stiff neck, joint pain, and swollen lymph nodes. After 3 to 5 days of symptoms, a red rash usually appears on the hands and feet and then spreads to the rest of the body. If the disease is not treated, it can cause death.

Anyone can get RMSF

People may be exposed when they spend time outdoors in tick-infested areas (such as wooded, brushy, or grassy places). Pets can bring ticks indoors and that may pose a risk to the household. RMSF is commonly seen during April through September, but can occur anytime during the year when there is warm weather.

Early diagnosis of RMSF is important. If you think you have RMSF, see your health care provider.

Early signs and symptoms of illness and a history of a tick bite help diagnose RMSF. Blood tests are available, but may be negative if done in the early stage of illness. If early blood tests are negative, a follow up test is recommended two to three weeks later.

RMSF can be treated with antibiotics

Call your doctor if you think you have RMSF or if you feel sick after getting a tick bite.

You can prevent RMSF

  • Avoid areas heavily infested with ticks (woods, tall grassy areas).
  • Use tick repellent according to the directions on the product label.
  • Wear light-colored clothes to help spot ticks.
  • Wear protective clothing (long pants and long-sleeved shirts, tuck pant legs into socks, and tuck shirt into pants) when in areas where you may have frequent or prolonged exposure to ticks.
  • Inspect your entire body (head to toe) for ticks after being outdoors.
  • Inspect both your children and pets for ticks after they have been outdoors.
  • Remove an attached tick by grasping the tick close to the skin surface and pulling straight back with steady force; use pointed tweezers to grasp the tick. If fingers must be used, protect bare hands with gloves, cloth, or tissue. Do not squeeze the tick's body or use petroleum jelly, lighted cigarettes, matches, or alcohol. Clean the bite site after removing a tick, and then wash your hands.
  • Mark on your calendar when a tick is taken off your body. This information will be useful to your doctor.
  • Keep the grass in your yard cut; remove leaves and leaf litter; clear brush from the yard.

Household pets (dogs, cats) get RMSF and may carry ticks inside the home

  • Try to prevent pets from going into areas infested with ticks (e.g., woods, fields).
  • Brush loose ticks off before letting pets into the house.
  • Remove all ticks in the same way as you would from yourself.
  • Talk to your veterinarian about tick control products.