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Rocky Mountain Spotted Fever

Rocky Mountain Spotted Fever

American Dog Tick

What is Rocky Mountain spotted fever?

  • Rocky Mountain spotted fever (RMSF) is a bacterial disease caused by the bacterium, Rickettsia rickettsii.  
  • RMSF is one of the deadliest tickborne diseases in the U.S.
  • RMSF is transmitted by ticks, most commonly the American dog tick (Dermacentor variabilis).  
  • The American dog tick is the most common tick in Michigan, human cases of RMSF are rare but do occur.  
  • Rocky Mountain spotted fever can be fatal if treatment is not started within the first 5 days of illness.  
  • Physicians in Michigan who suspect RMSF should begin treatment with doxycycline immediately and not wait for results of laboratory testing.
  • Preventing tick bites is the best way to avoid getting RMSF.

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    • Got A TICK? SUBMIT IT FOR ID, Information on identifying and testing ticks

      GOT A TICK? SUBMIT A PIC! Click here for more information on picture ID

      MiTracking, Michigan Environmental Public Health Tracking

      Emerging and Zoonotic Disease Surveillance Summary

      Link to 2021 Michigan Trends in Tickborne Disease Report

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      • RMSF is the deadliest tick-borne disease in the U.S.
      • It is spread by several ticks in the U.S. including the American dog tick, Rocky Mountain wood tick, and the brown dog tick (parts of the SW U.S. and Mexico). 
      • Anyone living or recreating where these ticks are present may be at risk. 
      • Rocky Mountain spotted fever has been diagnosed throughout the U.S., however cases are most commonly reported from North Carolina, Tennessee, Missouri, Arkansas, and Oklahoma. 
      • Children under 10 years old, American Indians, people with a compromised immune system, and people with delayed treatment are at an increased risk of fatal outcome from RMSF. 
      • The majority of cases reported have an illness onset during the months of June and July.  However, the seasonality varies for different regions of the country.    

       

    • What are the signs and symptoms of RMSF?

      • Early symptoms can be non-specific, including fever and headache, but can rapidly progress and become life threatening.
      • See your healthcare provider if you become ill after a tick bite or having been in the brushy or woodsy areas where ticks commonly live.
      • The first symptoms of Rocky Mountain spotted fever (RMSF) typically begin 2-14 days after the bite of an infected tick. 
      • The disease is characterized by acute fever, headache, muscle pain, vomiting, and general discomfort. 
      • A rash may also develop 2-4 days after the fever begins and often spreads with time. 
      • Approximately 90% of infected individuals will develop some type of rash, however, the rash may not develop until later in the disease process. 
      • RMSF can be life-threatening, but early treatment with doxycycline can prevent disability and death.
      • Some patients who survive RMSF can be left with long term health effects including neurological deficits, damage to internal organs, and vascular damage requiring amputation of some extremities.

       

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      How is RMSF diagnosed? 

      • Early symptoms of RMSF may resemble other diseases. 
      • Diagnostic tests, especially those based on the detection of antibodies, will often appear negative for the first 7-10 days of illness. 
      • The diagnosis of RMSF is based on clinical suspicion alone. 
      • Treatment is most effective at preventing death if started in the first five days of symptoms.
      • The diagnosis must be made and treatment initiated based on clinical signs and symptoms, and can later be confirmed using specialized confirmatory laboratory tests.
      • Rickettsial Disease Testing and Interpretation

      What should I do if I have a tick that I want to identify?

      • Knowing what kind of tick bit you may be important in knowing what your risk of disease is.  
      • The Michigan Department of Health and Human Services (MDHHS) provides tick identification at no charge to Michigan citizens.
      • There are two ways to have a tick identified, 1) By submitting a photo of your tick, or, 2) by sending the tick to the MDHHS for microscopic identification. 
      • If you want to submit a photo of your tick, the MDHHS will make all attempts to identify the tick based on the condition of the tick and the condition of the photos. 
      • Definitive tick identification may only be made by sending the tick for microscopic examination.  

      Click HERE for instructions on how to submit a photo of your tick for identification

      Click HERE for instructions on how to ship a tick to the MDHHS for microscopic identification
       

      RMSF information for clinicians

       CDC:  Tickborne Diseases of the United States

      The Michigan Department of Health and Human Services Bureau of Laboratories can assist Michigan healthcare providers with RMSF diagnostic testing:

      MDHHS BOL Mosquito-Borne and Tick-Borne Disease Testing

       

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      What is the treatment for RMSF?

      Treatment should never be delayed pending the receipt of laboratory test results, or be withheld on the basis of an initial negative finding. 

      • The antibiotic doxycycline is the first line treatment for adults and children of all ages and should be initiated immediately whenever RMSF is suspected.
      • Treatment is most effective at preventing severe complications, including death, if started within the first 5 days of symptoms. 
      • Treatment should continue for at least 3 days after the fever subsides and there is evidence of improvement for a minimum of 5-7 days.

       

    • There is no vaccine to prevent RMSF.

      Prevent illness from RMSF by preventing:

      Tick Bites

      Ticks on your Pets

      Ticks in Your Yard:  The Tick Management Handbook- Connecticut Agricultural Experiment Station

       

       

       

    • Michigan Resources

      • Ticks and Your Health - Brochure describing Lyme disease and other tick-borne diseases in Michigan. Other topics covered include tick-bite prevention, preventing ticks on pets, and landscape techniques to minimize tick risk.
      • Michigan's Five Most Common Ticks
      • Michigan Tick ID Card - Pocket-sized card for identifying common ticks in Michigan. Information regarding tick removal and tick-bite prevention.

      Centers for Disease Control and Prevention Resources

      For the Public

      For Healthcare Providers