Rocky Mountain Spotted Fever
Rocky Mountain spotted fever (RMSF) is a severe disease. It is potentially fatal. The disease is spread by ticks. It was first recognized in the Rocky Mountain states. RMSF is now found in practically all states in the US.
RMSF is caused by the bacterium Rickettsia rickettsii. It is carried by the American dog tick and the Rocky Mountain wood tick. When an infected tick bites a human, the disease is passed through the skin into the bloodstream.
The bacteria multiply inside cells of the inner lining of small arteries. This causes inflammation. The inflammation is known as vasculitis.
Factors that increase your chance of RMSF include:
The first symptom of RMSF is a sudden high fever. It often occurs within 1-14 days after a tick bite. Other symptoms may include:
Later signs may include:
The doctor will ask about your symptoms and medical history. A physical exam will be done. RMSF can be difficult to diagnose. It can resemble other diseases. Three indicators that your doctor will look for are:
Blood tests may be done to confirm the diagnosis. Treatment is often started based on a best guess basis. Sometimes doctors forget to think of RMSF when adults or children have only high fever.
Especially if you have been outdoors around ticks, ask your doctor:
RMSF is treated with antibiotics. It is important to start this treatment early. The most commonly used antibiotics are:
The best way to prevent RMSF is to limit your exposure to ticks. If you live in an area that is prone to ticks, take the following precautions:
Centers for Disease Control and Prevention (CDC)
National Library of Medicine
Canadian Family Physician
Public Health Agency of Canada
Bratton RL, Corey GR. Tick-borne disease. Am Fam Physician . 2005;71:2323.
Rocky mountain spotted fever. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated June 2009. Accessed July 21, 2009.
Rocky mountain spotted fever. Mayo Clinic website. Available at: http://www.mayocli... . Updated June 2009. Accessed July 21, 2009.
Last reviewed December 2011 by Rosalyn Carson-DeWitt, MD