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
• Chills
• 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.

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.

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.