Rocky Mountain Spotted Fever

What Is Rocky Mountain Spotted Fever?

Rocky Mountain spotted fever (RMSF) is a serious and potentially deadly tick-borne disease caused by the bacterium Rickettsia rickettsii. It’s the most common rickettsial infection in the United States, where it’s found mostly in the southeastern, mid-Atlantic, and southwestern parts of the country, but it can occur in any state. It’s potentially fatal if it’s not treated early. But with timely diagnosis and treatment, severe complications and death are rare.

Signs and Symptoms

Signs and symptoms usually begin two to 15 days after the tick bite. Symptoms can include:

  • Fever
  • Chills
  • Headache
  • Nausea and vomiting
  • Muscle pain
  • Lack of appetite
  • Body and joint pain
  • Fatigue
  • Rash

The rash may vary, including red spots, purple spots or rings, or no rash at all. The rash may begin on the ankles and wrists and spread to the rest of the body. The rash usually appears three to five days after the onset of symptoms.


The diagnosis of Rocky Mountain spotted fever is often suspected based on the patient's history and symptoms. Laboratory tests may be used to confirm the diagnosis and check for other tick-borne diseases. These tests may include:

  • Blood tests
  • Tick testing
  • Tissue sampling
  • Spinal tap for cerebral spinal fluid


Rocky Mountain spotted fever is treated with antibiotics. Treatment should begin as soon as possible. The sooner it’s started, the better the chance of recovery. Common antibiotics prescribed for Rocky Mountain spotted fever are doxycycline and tetracycline. Treatment typically lasts three to five days.


If treatment is delayed, complications can occur. These can include:

  • Pneumonia
  • Encephalitis
  • Organ failure
  • Death


The best way to prevent Rocky Mountain spotted fever is to protect yourself from tick bites. The Centers for Disease Control and Prevention (CDC) recommends the following measures:

  • Avoid areas with high grass and leaf litter.
  • Walk in the center of trails to avoid contact with overgrown grass, brush, and shrubs.
  • Use insect repellent that contains DEET and Permanone products with permethrin.
  • Wear long-sleeved shirts and long pants tucked into your socks or boots.
  • Check for ticks after spending time outdoors.


Rocky Mountain spotted fever can be fatal if not treated promptly. With early diagnosis and treatment, complications and death can usually be prevented. It’s important to know the symptoms and take measures to protect yourself from tick bites.