Rocky Mountain Spotted Fever (Rickettsiosis)

Rocky Mountain Spotted Fever (Rickettsiosis) is a tickborne disease caused by the bacterium Rickettsia rickettsii. This organism is a cause of potentially fatal human illness in North and South America, and is transmitted to humans by the bite of infected tick species.


The first symptoms of Rocky Mountain spotted fever (RMSF) typically begin 2-14 days after the bite of an infected tick. A tick bite is usually painless and about half of the people who develop RMSF do not remember being bitten. The disease frequently begins as a sudden onset of fever and headache and most people visit a healthcare provider during the first few days of symptoms. Because early symptoms may be non-specific, several visits may occur before the diagnosis of RMSF is made and correct treatment begins. The following symptoms are commonly seen with this disease; fever, rash (occurs 2-5 days after fever, may be absent in some cases; see below), headache , nausea, vomiting, abdominal pain (may mimic appendicitis or other causes of acute abdominal pain), muscle pain, lack of appetite, conjunctival injection (red eyes). It is important to note that few people with the disease will develop all symptoms, and the number and combination of symptoms varies greatly from person to person;

RMSF is a serious illness that can be fatal in the first eight days of symptoms if not treated correctly, even in previously healthy people. The progression of the disease varies greatly. Patients who are treated early may recover quickly on outpatient medication, while those who experience a more severe course may require intravenous antibiotics, prolonged hospitalization or intensive care.

How It Spreads

It spreads through the bite of infected ticks.


Reducing exposure to ticks is the best defense against Lyme disease, Rocky Mountain spotted fever, Babesiosis, Ehrliochiosis, and other tickborne infections. There are several steps you and your family can take to prevent and control tick borne diseases:

Removing Ticks

  • Using a pair of pointed (fine-tipped) tweezers, grasp the mouthparts of the tick as close to the skin as possible.
  • Pull the tick straight out with a firm and steady force.
  • Wash the area of the bite thoroughly with soap and water.
  • Do not attempt to remove the tick by touching it with a burnt match or swabbing it with alcohol or petroleum jelly.  (This will only aggravate the tick and cause it to release more bacteria into the blood stream.)
  • Do not squeeze the tick’s body when removing it and do not handle the tick with bare hands.

It takes roughly a day or two for ticks to transmit bacteria it is important to remove ticks from your skin as soon as you discover them. If there is a concern about incomplete tick removal, please contact your healthcare provider. (more)

Testing & Diagnosis

Methods such as serology and molecular methods can be used.


Rocky Mountain Spotted Fever can be treated with antibiotics.

Publications & Resources