What is Lyme disease?
Lyme disease (named after the town where it was discovered) is caused by the bacterium Borrelia burgdorferi when the bite of an infected tick (black legged tick) transfers the bacterium to humans during the tick's blood meal. Lyme disease typically cause fever, headache, fatigue, and often shows a characteristic skin rash that looks like a bull's-eye target (erythema migrans). The disease can spread to the joints, heart, and the nervous system. Other mammals can be infected (for example, dogs) by tick bites. However, direct human-to-human, animal-to-animal and transmission between humans and animals does not occur. Only if a tick bites an infected person or animal, becomes infected, and then bites another human or animal, can the disease be transferred.
Is Lyme disease contagious?
Lyme disease is not contagious from person to person and, to date, has not been reported to be transmitted sexually, by kissing, by blood transfusions, or infected animals (for example, pet dogs). Lyme disease is transmitted to humans by infected ticks, usually through the bites of ticks that are immature and are termed "nymphs." The ticks (nymph stage) are tiny (less than 2 mm diameter) and take about 36-48 hours of attachment to the human before the bacteria that cause Lyme disease are transmitted.
How will I know if I have Lyme disease?
Usually, a reddish expanding rash (erythema migrans) begins about three to 30 days after an infected tick bite. This rash occurs in about 70%-80% of individuals who become infected and spreads to about 12 inches in diameter and often forms a "bull's-eye" pattern on the skin. The rash may appear on other parts of the body also and may not form the "bull's-eye" pattern. Other symptoms and signs that may come and go are as follows:
Some individuals are not sure they have been bitten by a tick; these individuals who develop any of the symptoms above can be tested to see if they have evidence of Lyme disease. The testing should be done by their physician and the results must be carefully interpreted since the immunoassay tests for Lyme disease may sometimes give equivocal results. However, the U.S. Centers for Disease Control and Prevention (CDC) has developed a two-tiered immunoassay testing system for Lyme disease that is reasonably reliable.
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Lyme Disease Risk Factors
Lyme disease occurs most frequently in children 5-14 years of age and adults 40-50 years of age. The most substantial risk factor for Lyme disease is exposure to the ticks located in the high-risk areas of the country listed above, particularly in the New England states, as well as Minnesota and Wisconsin. Additional risk factors include recreational and occupational exposure to ticks and outdoor activities, including gardening, in woods and fields in the high-risk areas.
How is Lyme disease transmitted?
Lyme disease is transmitted through the bite of an infected tick and it is not spread from person to person. However, Lyme disease can spread in the community if large areas of tall grasses and brush that surround homes or other places where people congregate become areas where infected ticks reside and where people walk or congregate. Methods to reduce tall grasses and brushy areas where ticks like to live will help control spread of Lyme disease to other individuals. People can protect themselves from tick bites by utilizing repellent sprays and by covering their body with long pants and long-sleeve shirts to help prevent ticks from reaching exposed skin.
When will I know I am cured of Lyme disease? How long does Lyme disease last?
Patients treated with antibiotics in the early stages (about one to 30 days after an infected tick bite) usually recover fairly quickly (days to weeks) with no neurological or cardiac problems. A few individuals may go on to develop post-treatment Lyme disease syndrome (sometimes incorrectly termed "chronic Lyme disease") in which patients after an appropriate course of antibiotics still have lingering symptoms of fatigue, pain, joint, and muscle aches for up to about six months after antibiotics have been administered. The cause of the syndrome has not been identified, but some researchers think it may be due to a combination of immune responses and residual damage to cells. However, patients adequately treated with antibiotics no longer have the causative bacteria in their system during this syndrome, and this syndrome does not need to be treated with additional antibiotics.
When should I contact a medical caregiver about Lyme disease?
If you are unsure that you have been bitten by tick yet you develop a rash, especially if it begins to form a "bull's-eye" pattern, you should contact a physician. In addition, even if you know you have been infected with Lyme disease, you should contact your physician immediately for appropriate therapy. If you suspect that you have been misdiagnosed or undertreated for Lyme disease, contact your physician or an infectious-disease specialist. Also, if a pregnant woman becomes infected, she can transfer the disease to her fetus. If you're pregnant and suspect you may have been exposed to Lyme disease by tick bites, contact your OB/GYN physician immediately.
Medically Reviewed on 10/20/2016
Medically reviewed by Robert Cox, MD; American Board of Internal Medicine with subspecialty in Infectious Disease
United States. Centers for Disease Control and Prevention. "Lyme Disease." Aug. 14, 2015. <http://www.cdc.gov/lyme/>.