What is Lyme disease?
Lyme disease (Lyme borreliosis) is a bacterial infection that is spread by ticks. You may develop Lyme disease if you are bitten by an infected tick. Your risk of developing Lyme disease increases if an infected tick stays attached to your skin for 36 to 48 hours.
Lyme disease is the most common tickborne disease in the United States. 1 It also frequently occurs in Canada, Europe, and Asia. Lyme disease is not contagious and cannot be transmitted from person to person.
What causes Lyme disease?
Lyme disease is caused by the bacterium Borrelia burgdorferi. When ticks are infected with this type of bacterium, they can transmit it by biting humans or animals. Once
infected, you may develop Lyme disease within a few days or weeks.
In the United States, the two types of ticks that carry Lyme disease bacteria are:
Deer ticks, which spread Lyme disease in the northeastern and upper Midwestern U.S.
Western black-legged ticks, which spread Lyme disease along the Pacific coast—mostly northern California and Oregon.
What are the symptoms?
Early symptoms can include an expanding circular rash called erythema migrans, and flulike symptoms, such as body aches, fatigue, and mild fever. In the United States, about 80% of
people with Lyme disease develop a circular rash at the site of the tick bite. 3 However, some people don’t have any symptoms in the early stages of Lyme disease.
The incubation period—the time from when you are first infected until you develop symptoms—is usually around 7 to 14 days, but symptoms can develop anywhere from 3 to 31 days after you are bitten. If the early stage of Lyme disease goes unnoticed, later symptoms can include swelling and pain in joints (similar to arthritis); numbness and tingling in the hands, feet, or
back; persistent fatigue; poor memory and reduced ability to concentrate; and weakness or paralysis in the muscles of the face.
How is Lyme disease diagnosed?
Lyme disease is diagnosed by evaluating your symptoms and medical history and determining whether you have been exposed to infected ticks. Having the characteristic expanding circular rash is usually a sure sign of Lyme disease. Blood tests, such as the Lyme disease test, may
be used to confirm a diagnosis but are not usually necessary or practical for every tick bite. Most people who are bitten by a tick will not develop Lyme disease, especially if exposure to the tick occurred outside high-risk areas or if the tick did not stay attached to the skin
for 36 to 48 hours.
Misdiagnosis of Lyme disease is common, because the bacteria that cause the illness are difficult to detect with current lab tests and because symptoms of Lyme disease sometimes closely resemble those of other illnesses.
How is it treated?
Treatment with antibiotics usually cures Lyme quickly and completely. However, if Lyme disease goes ndetected or is not properly treated, problems involving the skin, joints, nervous system, and heart may develop weeks, months, or even years later. These problems usually improve after antibiotic treatment, but in rare cases they may be permanent. Most
people with Lyme disease who are diagnosed early and treated appropriately with antibiotics have no long-term disabilities resulting from the disease.