Rocky Mountain Spotted Fever


What is Rocky Mountain spotted fever?

Rocky Mountain spotted fever is a bacterial infection that can be life-threatening if you don’t treat it early. People get this infection when bitten by an infected tick.

When and where do people get Rocky Mountain spotted fever?

Despite its name, Rocky Mountain spotted fever can occur many places in the U.S, most commonly in the central and eastern states, including Missouri, Arkansas, the Carolinas and Tennessee. It also exists in Canada, Mexico, and areas of Central and South America.

You can get Rocky Mountain spotted fever at any time of the year. However, most cases happen during the warm summer months, when people are more likely to be exposed to ticks.

Symptoms and Causes

What causes Rocky Mountain spotted fever?

Bacteria called Rickettsia rickettsii causes Rocky Mountain spotted fever. The bacteria is spread to people through the bite of a tick. The ticks that carry this disease include the Rocky Mountain wood tick, the American dog tick, and the brown dog tick.

What are the symptoms of Rocky Mountain spotted fever?

Rocky Mountain spotted fever causes symptoms including a headache, fever and rash. Symptoms usually show up 2 to 14 days after a tick bite.

These symptoms are common to many illnesses, including influenza and meningitis. If you develop these symptoms and have been bitten by a tick or spent time in areas where ticks live, it is important to see a doctor because the disease can get worse very quickly.

Though the name “spotted fever” suggests a rash, not everyone with Rocky Mountain spotted fever develops a rash and it may be difficult to see on people with darker skin. If a rash does develop, it usually appears 2 to 4 days after the fever starts. The red dots of the rash can look different in different cases. They can range from small dots to large blotches.

Symptoms of Rocky Mountain spotted fever can get worse soon after the initial symptoms appear. See a doctor if you experience more severe problems including:

Diagnosis and Tests

How is Rocky Mountain spotted fever diagnosed?

Doctors use several tests to confirm a diagnosis of Rocky Mountain spotted fever. Blood tests can identify signs of the disease. These signs can include abnormal white blood cell levels and low levels of sodium in the blood. However, treatment is usually started before tests return.

Management and Treatment

How is Rocky Mountain spotted fever treated?

Doctors use medicines called antibiotics to treat Rocky Mountain spotted fever. Doxycycline is an antibiotic that may be used. Antibiotics kill the Rickettsia rickettsii bacteria that caused the infection. Treatment works best if started early.

What complications can Rocky Mountain spotted fever cause?

People with Rocky Mountain spotted fever who get early treatment usually recover quickly, without hospitalization. Serious cases, and people who wait too long to start treatment, may need to spend time in the hospital. In the hospital, people can receive antibiotics directly through a vein (intravenously).

Complications could include:

  • Confusion
  • Coma
  • Hearing loss
  • Loss of fingers, toes or even limbs if significant damage occurs to blood vessels


Can Rocky Mountain spotted fever be prevented?

No vaccine exists to prevent Rocky Mountain spotted fever. The only way to prevent the infection is to avoid being bitten by a tick. Some ways to avoid tick bites include:

  • Checking your clothes and skin for ticks regularly when in woods or grassy areas.
  • Using insect repellent for exposed skin and permethrin-containing compounds for clothing.
  • Checking pets for ticks before they come into your house.

Outlook / Prognosis

What is the outlook for people with Rocky Mountain spotted fever?

Most people with Rocky Mountain spotted fever who are treated quickly recover fully with no long-term effects.

What are the outcomes after people have Rocky Mountain spotted fever?

Doctors believe that once you get Rocky Mountain spotted fever, you develop a resistance to the infection (immunity). When people are immune, they will not get the infection again.

Last reviewed by a Cleveland Clinic medical professional on 06/04/2018.


  • Centers for Disease Control and Prevention. Rocky Mountain Spotted Fever (RMSF). ( Accessed 6/5/2018.
  • Ohio Department of Heath. Rocky Mountain Spotted Fever. ( Accessed 6/5/2018.
  • New York State Department of Health. Rocky Mountain Spotted Fever (tick-borne typhus fever). ( Accessed 6/5/2018.
  • OhioLine. Tick and Tick-borne Diseases. ( Accessed 6/5/2018.

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