All about Rocky Mt. Spotted Fever

All the facts that you need to know

What is Rocky Mt. Spotted Fever (RMSF)

RMSF is a serious illness that can be very dangerous in the first eight days of symptoms if not treated correctly. Patients who get treated early could possibly recover quickly on medication, but those who experience a severe course may need antibiotics, prolonged hospitalization or intensive care.


  • 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)


The first symptoms of Rocky Mountain spotted fever (RMSF) usually begins 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 begins as a sudden 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. 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.

Long-term Health Problems

Patients who had a particularly severe infection requiring prolonged hospitalization may have long-term health problems caused by this disease. Rickettsia rickettsii infects the endothelial cells that line the blood vessels. The damage that occurs in the blood vessels results in a disease process called a "vasculitis", and bleeding or clotting in the brain or other vital organs occur. Loss of fluid from damaged vessels results in loss of circulation to the extremities and damaged fingers, toes or even limbs may ultimately need to be amputated. Patients who suffer this kind of severe vasculitis in the first two weeks of illness may also be left with permanent long-term health problems such as profound neurological deficits, or damage to internal organs. Those who dont have this kind of vascular damage in the initial stages of the disease typically recover fully within several days to months.


Doxycycline is the first line treatment for adults and children of all ages and should be initiated immediately whenever RMSF is suspected.

Infection in Children

Children with RMSF infection may experience nausea, vomiting, and loss of appetite. Children are less likely to report a headache, but more likely to develop an early rash than adults. Others observed signs and symptoms in children with RMSF are abdominal pain, altered mental status, and conjunctival injection. Occasionally, symptoms like cough, sore throat, and diarrhea may be seen, and can lead to misdiagnosis.

The RMSF Rash

While most people with RMSF (90%) have some type of rash during the illness, some people do not develop the rash until late in the disease process, after treatment should have already begun. Approximately 10% of RMSF patients never develop a rash. It is important for physicians to consider RMSF if other signs and symptoms support a diagnosis, even if a rash is not present.

A classic case of RMSF involves a rash that first appears 2-5 days after the fever as small, flat, pink, non-itchy spots (macules) on the wrists, forearms, and ankles and spreads to include the trunk and sometimes the palms and soles. Often the rash varies from this description and people who fail to develop a rash, or develop an atypical rash, are at increased risk of being misdiagnosed.

The red to purple, spotted (petechial) rash of RMSF is usually not seen until the sixth day or later after onset of symptoms and occurs in 35-60% of patients with the infection. This is a sign of progression to severe disease, and every attempt should be made to begin treatment before petechiae develops.