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Rocky Mountain spotted fever




What is Rocky Mountain spotted fever?

Rocky Mountain spotted fever (RMSF) is the most severe tick-borne illness in the United States. Although this disease was reported most frequently in the Rocky Mountain area early after its discovery, relatively few cases are reported from this area today. The majority of patients with RMSF require hospitalization, and about 3 to 5 percent of cases reported in recent years in the United States have been fatal. 


How do people get RMSF?

RMSF is transmitted by the bite of an infected tick. The American dog tick and Rocky Mountain wood tick are the primary vectors of RMSF bacteria in the United States.   A minimum of 4-6 hours of attachment is necessary for transmission to occur in people.


What are the symptoms?

Initial symptoms may include fever, nausea, vomiting, muscle pain, lack of appetite and severe headache.  Later signs and symptoms include rash, abdominal pain, joint pain, and diarrhea. Patients infected with RMSF usually visit a physician in their first week of illness, following an incubation period of about 5-10 days after a tick bite.


How is RMSF diagnosed?

A diagnosis of RMSF is based on a combination of clinical signs and symptoms and specialized confirmatory laboratory tests.  Your healthcare provider will determine if laboratory testing is needed. 


How is RMSF treated?

RMSF is best treated by using a tetracycline antibiotic, usually doxycycline. Patients are treated for at least 3 days after the fever subsides and until there is evidence of clinical improvement.  The standard duration of treatment is 5 to 10 days.  Infection with RMSF provides long lasting immunity against re-infection. However, prior illness with RMSF should not deter persons from practicing good tick-preventive measures or visiting a physician if signs and symptoms consistent with RMSF occur, especially following a tick bite.


How can tick-borne diseases be prevented?

Limiting exposure to ticks reduces the likelihood of CTF virus infection. Tick-infested habitats should be avoided. In Wyoming, that would be areas of heavy sage brush. Additional prevention measures include: 

  • Use pest collars or treatments on dogs and cats that are allowed to roam outside. Speak with your veterinarian for recommendations on specific products.
  • Wear light-colored clothing to allow you to see ticks that are crawling on your clothing.
  • Tuck your pants legs into your socks so that ticks cannot crawl up the inside of your pants legs.
  • Wear long sleeves and tuck your shirt into your pants
  • Apply repellants to discourage tick attachment. Repellents containing permethrin can be sprayed on boots and clothing. Repellents containing 20% or more DEET (n, n-diethyl-m-toluamide) can also help deter ticks. 
  • Perform tick checks on humans and pets immediately upon returning from outings.
  • And finally, prompt and proper tick removal is essential.


To remove attached ticks, use the following procedure:

1.       Use fine-tipped tweezers or shield your fingers with a tissue, paper towel, or rubber gloves. When possible, persons should avoid removing ticks with bare hands.

2.       Grasp the tick as close to the skin surface as possible and pull upward with steady, even pressure. Do not twist or jerk the tick; this may cause the mouthparts to break off and remain in the skin. (If this happens, remove mouthparts with tweezers. Consult your health care provider if infection occurs.)

3.       Do not squeeze, crush, or puncture the body of the tick because its fluids (saliva, body fluids, gut contents) may contain infectious organisms.

4.       After removing the tick, thoroughly disinfect the bite site and wash your hands with soap and water.

5.       Save the tick for identification in case you become ill. This may help your doctor make an accurate diagnosis. Place the tick in a plastic bag and put it in your freezer. Write the date of the bite on a piece of paper with a pencil and place it in the bag.


Folklore remedies, such as the use of petroleum jelly or hot matches, do little to encourage a tick to detach from skin. In fact, they may make matters worse by irritating the tick and stimulating it to release additional saliva or regurgitate gut contents, increasing the chances of transmitting the pathogen. These methods of tick removal should be avoided.