Filed under: Infectious Diseases
Rocky Mountain spotted fever is a potentially serious bacterial infection transmitted to humans by tick bites. The illness is named after the Rocky Mountain region, where the disease was first identified. Rocky Mountain spotted fever occurs when an infected tick attaches to your skin and feeds on your blood. The infection then has the potential to spread to your bloodstream and other areas of your body.
Rocky Mountain spotted fever doesn't spread directly from person to person. If treated promptly, a case of Rocky Mountain spotted fever is usually fairly mild. In a small number of people, the disease can be serious, even fatal, especially in older adults. Because Rocky Mountain spotted fever can progress rapidly, prompt treatment is important.
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Initial signs and symptoms of Rocky Mountain spotted fever often are nonspecific and can mimic those of other illnesses:
Later on, these signs and symptoms of Rocky Mountain spotted fever can develop:
Although many people experience symptoms within the first week after being bitten by an infected tick, the illness could incubate for up to 14 days after the tick bite.
Characteristic red rash
In most cases of Rocky Mountain spotted fever, a red, blotchy rash develops on the wrists and ankles, spreading to the palms of your hands and soles of your feet. This usually occurs between days three and five of infection. The rash often spreads up your arms and legs to your torso.
A few people who are infected don't ever develop a rash. If your skin is darkly pigmented, a rash might not be readily apparent. However, the absence of a rash doesn't indicate a milder form of illness and may make the condition more difficult to diagnose.
When to see a doctor
See your doctor if you develop a rash or become sick after a tick bite. Rocky Mountain spotted fever and other infectious diseases carried by ticks can progress rapidly and may be life-threatening. If possible, take the tick along with you to your doctor's office for laboratory testing.
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Rocky Mountain spotted fever is caused by infection with the organism Rickettsia rickettsii. The bacterium infects you when you come in contact with an infected tick in one of these circumstances:
The culprit ticks
The bacterium that causes Rocky Mountain spotted fever typically is carried by a family of ticks known as Ixodidaeor hard ticks. These ticks live in the low bushes and tall grasses of wooded areas and are more abundant in late spring and early summer.
In the western United States, Rocky Mountain spotted fever is transmitted by the wood tick (Dermacentor andersoni). In the eastern United States, where the disease is most common, it's transmitted by the American dog tick (Dermacentor variabilis). In the southern United States, Central America and South America, Rocky Mountain spotted fever is transmitted by other ticks, such as the cayenne tick (Amblyomma cajennense) and the brown dog tick (Rhipicephalus sanguineus).
Rocky Mountain spotted fever primarily occurs when ticks are most active and during warm weather when people tend to spend more time outdoors.
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Your risk of contracting Rocky Mountain spotted fever depends on:
It's important to take precautions against exposure to ticks and to be sure to check yourself and your dog for ticks after being outside.
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
If detected in its early stages, Rocky Mountain spotted fever can be most successfully treated with medication. Left untreated, the infection can spread from the site of the bite via your bloodstream, potentially causing infection in other areas of your body. Rocky Mountain spotted fever may cause serious complications involving your joints, heart, lungs, kidneys, and central and peripheral nervous system, such as:
In a small percentage of cases, Rocky Mountain spotted fever causes death, usually because treatment is delayed or is never sought.
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
You'll likely start by first seeing your family doctor or primary care provider. In some cases, you might be referred immediately to a doctor who specializes in infectious diseases.
Here's some information to help you prepare for your appointment, and what to expect from your doctor.
What you can do
For Rocky Mountain spotted fever, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time if you don't understand something.
What to expect from your doctor
Your doctor or health care provider is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on.
Questions your doctor might ask include:
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Your doctor will diagnose Rocky Mountain spotted fever by:
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
Treatment for Rocky Mountain spotted fever involves:
The sooner treatment begins, the better. The disease can progress rapidly and may cause serious illness. People who develop Rocky Mountain spotted fever are much more likely to survive if treated within five days of developing symptoms. That's why your doctor will probably have you begin antibiotic therapy before receiving conclusive test results, if he or she suspects Rocky Mountain spotted fever is the cause of your symptoms.
Doxycycline is the most effective treatment for Rocky Mountain spotted fever, but it's not a good choice if you're pregnant. In that case, your doctor may prescribe chloramphenicol as an alternative.
How to safely remove a tick
If you find a tick crawling on your skin, carefully remove it. Don't crush it between your fingers. Instead, burn it, bury it or flush it. Be sure to wash your hands afterward.
If a tick has already bitten you and is holding on to your skin, follow these steps:
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.
You can decrease your chances of contracting Rocky Mountain spotted fever by taking some simple precautions:
©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.


