Lyme disease is caused by bacteria called Borrelia burgdorferi (B. burgdorferi). Blacklegged ticks carry these bacteria. The ticks pick up the bacteria when they bite mice or deer that are infected with Lyme disease. You can get the disease if you are bitten by an infected tick.
Lyme disease was first reported in the United States in the town of Old Lyme, Connecticut, in 1975. In the United States, most Lyme disease infections occur in the following areas:
Northeastern states, from Virginia to Maine
North-central states, mostly in Wisconsin and Minnesota
West Coast, particularly northern California
There are 3 stages of Lyme disease. (See below for symptoms.)
Stage 1 is called early localized Lyme disease. The infection is not yet widespread throughout the body.
Stage 2 is called early disseminated Lyme disease. The bacteria have begun to spread throughout the body.
Stage 3 is called late disseminated Lyme disease. The bacteria have spread throughout the body.
Risk factors for Lyme disease include:
Doing outside activities that increase tick exposure (for example, gardening, hunting, or hiking) in an area where Lyme disease is known to occur
Having a pet that may carry ticks home
Walking in high grasses
Important facts about tick bites and Lyme disease:
In most cases, a tick must be attached to your body for 24 - 36 hours to spread the bacteria to your blood.
Blacklegged ticks can be so small that they are almost impossible to see. Many people with Lyme disease never even saw a tick on their body.
Most people who are bitten by a tick do not get Lyme disease.
Symptoms of early localized Lyme disease (Stage 1) begin days or weeks after infection. They are similar to the flu and may include:
There may be a "bull's eye" rash, a flat or slightly raised red spot at the site of the tick bite. Often there is a clear area in the center. It can be quite large and expanding in size.
Symptoms may come and go. Untreated, Lyme disease can spread to the brain, heart, and joints.
Symptoms of early disseminated Lyme disease (Stage 2) may occur weeks to months after the initial tick bite. They may include:
Paralysis or weakness in the muscles of the face
Muscle pain and pain or swelling in the knees and other large joints
Heart problems, such as skipped heartbeats (palpitations)
Symptoms of late disseminated Lyme disease (Stage 3) can occur months or years after the initial infection. The most common symptoms are muscle and joint pain. Other symptoms may include:
Abnormal muscle movement
Numbness and tingling
Signs and tests
A blood test can be done to check for antibodies to the bacteria that cause Lyme disease. The most commonly used is the ELISA for Lyme disease test. A western blot test is done to confirm ELISA results.
In areas where Lyme disease is more common, your health care provider may be able to diagnose early disseminated Lyme disease (Stage 1) without doing any lab tests.
Other tests that may be done, when the infection has become more widespread, include:
Echocardiogram to look at the heart
Spinal tap (lumbar puncture to examine spinal fluid
MRI of the brain
Anyone who has been bitten by a tick should be watched closely for at least 30 days.
A single dose of antibiotics may be offered to someone soon after being bitten by a tick, if all of the following are true:
The person has a tick that can carry Lyme disease attached to their body. This usually means that a nurse or physician has looked at and identified the tick.
The tick is thought to have been attached to the person for at least 36 hours.
The person can begin taking the antibiotics within 72 hours of removing the tick.
The person is over 8 years old and is not pregnant or breastfeeding.
A 2 - 4-week course of antibiotics is used to treat people who are diagnosed with Lyme disease. The specific antibiotic used depends on the stage of the disease and the symptoms.
Pain medications, such as ibuprofen, are sometimes prescribed to relieve joint stiffness.
If diagnosed in the early stages, Lyme disease can be cured with antibiotics. Without treatment, complications involving the joints, heart, and nervous system can occur. However, these symptoms are still treatable.
Rarely, a person will continue having symptoms that can interfere with daily life even after they have been treated with antibiotics. Some people call this post-Lyme disease syndrome. The cause is unknown.
Stage 3, or late disseminated, Lyme disease can cause long-term joint inflammation (Lyme arthritis) and heart rhythm problems. Brain and nervous system problems are also possible, and may include:
Paralysis of the face muscles
Calling your health care provider
Call your health care provider if you have:
A large, red, expanding rash that may look like a bull's eye
Had a tick bite and develop weakness, numbness, or tingling, or heart problems
Symptoms of Lyme disease, especially if you may have been exposed to ticks
Take precautions to avoid direct contact with ticks. Be extra careful during warmer months. Whenever possible:
Avoid wooded or bushy areas, or areas with high grasses and leaf litter.
Walk in the center of trails.
Check yourself and your pets frequently during and after your walk or hike.
When walking or hiking in wooded or grassy areas, spray all exposed skin and your clothing with insect repellant.
You may also treat clothing, such as boots, pants, and socks, with a product that contains permethrin. It remains protective for several washings.
Ticks that carry Lyme disease are so small that they are very hard to see. After returning home, remove your clothes and thoroughly inspect all skin surface areas, including your scalp. Shower soon after coming indoors to wash off any unseen ticks.
Halperin JJ, Shapiro ED, Logigian E, Belman AL, Dotevall L, Wormser GP, et al. Practice parameter: treatment of nervous system Lyme disease (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2007;69:91-102.
Lyme disease. CDC. Page last updated April 12, 2011. Viewed August 24, 2011.
Steere AC. Borrelia burgdorferi (lyme disease, lyme borreliosis). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 242.
Wormser GP, Dattwyler RJ, Shapiro ED, et al. The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: Clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006;43(9):1089-1134.
A.D.A.M. Editorial: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Jatin M. Vyas, MD, PhD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital (3/11/2011).