Lyme disease is a bacterial infection you get from the bite of an infected tick. At first, Lyme disease usually causes symptoms such as a rash, fever, headache, and fatigue. But if it is not treated early, the infection can spread to your joints, heart, and nervous system. Prompt treatment can help you recover quickly.

Lyme disease is caused by bacteria. In the United States, this is usually a bacterium called Borrelia burgdorferi. It spreads to humans through the bite of an infected tick. The ticks that spread it are blacklegged ticks (or deer ticks). They are usually found in the:

• Northeast
• Mid-Atlantic
• Upper Midwest
• Pacific coast, especially northern California

These ticks can attach to any part of your body. But they are often found in hard-to-see areas such as your groin, armpits, and scalp. Usually, the tick must be attached to you for more than 24 hours to spread the bacterium to you.

Most tick bites happen in the warmer months (April-September), when ticks are most active and people spend more time outdoors. But you can also get bitten during the rest of the year, especially if the temperatures are warmer than usual.

Most tick bites happen in the summer months when ticks are most active and people spend more time outdoors. But you can get bitten in the warmer months of early fall, or even late winter if temperatures are unusually high. And if there is a mild winter, ticks may come out earlier than usual.

Early symptoms of Lyme disease start between 3 to 30 days after an infected tick bites you. The symptoms can include:

• A red rash called erythema migrans (EM). Most people with Lyme disease get this rash. It gets bigger over several days and may feel warm. It is usually not painful or itchy. As it starts to get better, parts of it may fade. Sometimes this makes the rash look like a "bull's-eye."
• Fever
• Chills
• Headache
• Fatigue
• Muscle and joint aches
• Swollen lymph nodes ("swollen glands")

If the infection is not treated, it can spread to your joints, heart, and nervous system. The symptoms may include:

• Severe headaches and neck stiffness.
• More EM rashes on other areas of your body.
• Facial palsy, which is a weakness in your facial muscles. It can cause drooping on one or both sides of your face.
• Arthritis with severe joint pain and swelling, especially in your knees and other large joints.
• Pain that comes and goes in your tendons, muscles, joints, and bones.
• Heart palpitations, which are feelings that your heart is skipping a beat, fluttering, pounding, or beating too hard or too fast.
• An irregular heart beat (Lyme carditis).
• Episodes of dizziness or shortness of breath.
• Inflammation of the brain and spinal cord.
• Nerve pain.
• Shooting pains, numbness, or tingling in the hands or feet.

To make a diagnosis, your health care provider will consider:

• Your symptoms
• How likely it is that you were exposed to infected blacklegged ticks
• How likely it is that you could have other illnesses that cause similar symptoms
• The results of any lab tests

Most Lyme disease tests check for antibodies made by the body in response to infection. These antibodies can take several weeks to develop. If you are tested right away, it may not show that you have Lyme disease, even if you have it. So you may need to have another test later.

Lyme disease is treated with antibiotics. The earlier you are treated, the better; it gives you the best chance of fully recovering quickly.

After treatment, some patients may still have pain, fatigue, or difficulty thinking that lasts more than 6 months. This is called post-treatment Lyme disease syndrome (PTLDS). Researchers don't know why some people have PTLDS. There is no proven treatment for PTLDS; long-term antibiotics have not been shown to help. However, there are ways to help with the symptoms of PTLDS. If you have been treated for Lyme disease and still feel unwell, contact your health care provider about how to manage your symptoms. Most people do get better with time. But it can take several months before you feel better.

To prevent Lyme disease, you should lower your risk of getting a tick bite:

• Avoid areas where ticks live, such as grassy, brushy, or wooded areas. If you are hiking, walk in the center of the trail to avoid brush and grass.
• Use an Environmental Protection Agency (EPA)-registered insect repellent when you go outdoors. They are evaluated to make sure they are safe and effective. Make sure that the repellant has one of these ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus, or para-menthane-diol. It is important to follow the instructions on the label.
• Treat your clothing and gear with a repellant containing 0.5% permethrin
• Wear light-colored protective clothing, so you can easily see any ticks that get on you
• Wear a long-sleeved shirt and long pants. Also tuck your shirt into your pants and your pant legs into your socks.
• Check yourself, your children, and your pets daily for ticks. Carefully remove any ticks you find.
• Take a shower and wash and dry your clothes at high temperatures after being outdoors

Centers for Disease Control and Prevention