Rocky Mountain spotted fever
Medically reviewed on October 20, 2017
Rocky Mountain spotted fever is a bacterial infection transmitted by a tick. Without prompt treatment, Rocky Mountain spotted fever can cause serious damage to internal organs, such as your kidneys and heart.
Although it was first identified in the Rocky Mountains, Rocky Mountain spotted fever is most commonly found in the southeastern part of the United States. It also occurs in parts of Canada, Mexico, Central America and South America.
Early signs and symptoms of Rocky Mountain spotted fever include a severe headache and high fever. A few days later, a rash usually appears on the wrists and ankles. Rocky Mountain spotted fever responds well to prompt treatment with antibiotics.
Although many people become ill within the first week after infection, signs and symptoms may not appear for up to 14 days. Initial signs and symptoms of Rocky Mountain spotted fever often are nonspecific and can mimic those of other illnesses:
- High fever
- Severe headache
- Muscle aches
- Nausea and vomiting
- Confusion or other neurological changes
Rash is distinctive
The red, nonitchy rash associated with Rocky Mountain spotted fever typically appears three to five days after the initial signs and symptoms begin. The rash usually makes its first appearance on your wrists and ankles, and can spread in both directions — down into the palms of your hands and the soles of your feet, and up your arms and legs to your torso.
Some people who are infected with Rocky Mountain spotted fever don't ever develop a rash, which makes diagnosis much more difficult.
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 available, take the tick along with you to your doctor's office for laboratory identification.
Rocky Mountain spotted fever may cause a rash of small red spots or blotches that begin on the wrists, palms or soles. The rash often spreads to the arms, legs and torso.
Rocky Mountain spotted fever is caused by infection with the organism Rickettsia rickettsii. Ticks carrying R. rickettsii are the most common source of infection.
If an infected tick attaches itself to your skin and feeds on your blood for six to 10 hours, you may pick up the infection. But you may never see the tick on you.
Rocky Mountain spotted fever primarily occurs when ticks are most active and during warm weather when people tend to spend more time outdoors. Rocky Mountain spotted fever cannot be spread from person to person.
Rocky Mountain spotted fever is caused by the organism Rickettsia rickettsii. In the United States, this bacterium most often is spread to humans by bites from the American dog tick or the wood tick, depending on the geographic area.
Factors that may increase your risk of contracting Rocky Mountain spotted fever include:
- Living in an area where the disease is common
- The time of year — infections are more common in the spring and early summer
- How much time you spend in grassy or wooded areas
- Whether you have a dog or spend time with dogs
If an infected tick attaches to your skin, you can contract Rocky Mountain spotted fever when you remove it, as fluid from the tick can enter your body through an opening such as the bite site.
You can reduce your risk of infection by taking steps to prevent exposure to ticks and tick fluids. When removing a tick from your skin:
- Use a tweezers to grasp the tick near its head or mouth and remove it carefully
- Treat the tick as if it's contaminated; soak it in alcohol or flush it down the toilet
- Clean the bite area with antiseptic
- Wash your hands thoroughly
Rocky Mountain spotted fever damages the lining of your smallest blood vessels, causing the vessels to leak or form clots. This may cause:
- Inflammation of the brain (encephalitis). In addition to severe headaches, Rocky Mountain spotted fever can cause inflammation of the brain, which can cause confusion, seizures and delirium.
- Inflammation of the heart or lungs. Rocky Mountain spotted fever can cause inflammation in areas of the heart and lungs. This can lead to heart failure or lung failure in severe cases.
- Kidney failure. Your kidneys filter waste from your blood, and the blood vessels within the kidneys are very small and fragile. Damage to these vessels can eventually result in kidney failure.
- Serious infection, possibly amputation. Some of your smallest blood vessels are in your fingers and toes. If these vessels don't work properly, the tissue at your farthest extremities may develop gangrene and die. Amputation would then be necessary.
- Death. Untreated, Rocky Mountain spotted fever has, historically, had a death rate as high as 80 percent.
You can decrease your chances of contracting Rocky Mountain spotted fever by taking some simple precautions:
Wear long pants and sleeves. When walking in wooded or grassy areas, wear shoes, long pants tucked into socks and long-sleeved shirts. Try to stick to trails and avoid walking through low bushes and long grass.
Use insect repellents. Products containing DEET (Off! Deep Woods, Repel) often repel ticks. Be sure to follow the instructions on the label. Clothing that has permethrin impregnated into the fabric is toxic to ticks and also may be helpful in decreasing tick contact when outdoors.
Do your best to tick-proof your yard. Clear brush and leaves where ticks live. Keep woodpiles in sunny areas.
Check yourself and your pets for ticks. Do this after being in wooded or grassy areas. Some ticks are no bigger than the head of a pin, so you may not discover them unless you are very careful.
Remove a tick with tweezers. Gently grasp the tick near its head or mouth. Don't squeeze or crush the tick, but pull carefully and steadily. Once you have the entire tick removed, wash the bite area with rubbing alcohol or soap and water.
Soak the tick in alcohol or flush it down the toilet. Wash your hands thoroughly to make sure any infected tick fluid is completely removed.
Though there are many purportedly effective methods for helping to remove a tick, such as petroleum jelly, alcohol or even applying a hot match to the tick's body, none is a good method for tick removal.
Rocky Mountain spotted fever can be difficult to diagnose because the early signs and symptoms are similar to those caused by many other diseases.
Laboratory tests can check a blood sample, rash specimen or the tick itself for evidence of the organism that causes the infection. Because early treatment with antibiotics is so important, doctors don't wait for these test results before starting treatment if Rocky Mountain fever is strongly suspected.
People who develop Rocky Mountain spotted fever are much more likely to avoid complications 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.
Doxycycline (Monodox, Vibramycin, others) 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.
Preparing for an appointment
You'll likely start by seeing your family doctor. In some cases, you might be referred to a doctor who specializes in infectious diseases.
What you can do
- Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if you need to do anything in advance.
- Note down any symptoms you're experiencing, even if they seem unrelated to the reason you have scheduled the appointment.
- Write down key personal information, including any recent life changes or travel.
- List all of the drugs, vitamins or supplements that you're currently taking or have taken recently.
- Write down a list of questions to ask your doctor.
Preparing a list of questions can help you make the most of your time with your doctor. For Rocky Mountain spotted fever, some basic questions to ask your doctor include:
- What's the most likely cause of my symptoms?
- Do I need any tests?
- What treatments are available? Which do you recommend?
- Do I need follow-up testing?
- I have other health problems. How can I best manage these conditions together?
What to expect from your doctor
Your doctor is likely to ask questions, such as:
- What are your symptoms, and when did they start?
- Have you recently been bitten by a tick?
- Do you spend a lot of time outdoors in grassy or wooded areas?
- Have you recently removed any ticks from family pets?
- Is anyone else in your family ill?
- Have you traveled anywhere recently?