Is Lyme Disease Contagious?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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.

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.

Medically Reviewed by a Doctor on 10/20/2016

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