Also Known As
Borrelia burgdorferi Infection
Borrelia mayonii Infection
This article was last reviewed on
This article waslast modified on August 23, 2019.
What is Lyme disease?

Lyme disease is an infection caused by the bacteria Borrelia burgdorferi and Borrelia mayonii. The infection is primarily spread to humans by bites from infected deer ticks, also known as black-legged ticks. People bitten by an infected tick may develop an inflammatory condition, which first affects the skin and then may spread to the joints, nervous system, and other parts of the body.

The ticks that cause Lyme disease are tiny, about the size of the head of a pin or a speck of dirt. They can be found anywhere on the body but tend to attach themselves to areas such as the scalp and groin. Not everyone who finds these ticks on their body will be infected by Borrelia, and many who are bitten will not develop Lyme disease. This is because not every tick is infected and because it can take from 24 to 72 hours after a tick attaches to transmit the bacteria.

According to statistics available from the Centers for Disease Control and Prevention (CDC), more than 40,000 cases of Lyme disease are reported in the U.S. each year. Cases are mostly concentrated in the Northeast and upper Midwest. In 2015, about 95% of Lyme disease cases were reported from 14 states, but the CDC says that the areas with high incidence of Lyme disease appear to be expanding. (See the map on this CDC web page.) The vast majority of the cases occur in the spring and summer when people spend more time outside and the ticks are most active.

The CDC estimates that the actual number of people in the U.S. who are diagnosed with Lyme disease each year is roughly 10 times the number reported. The higher estimate of 400,000 cases annually is based on data from ongoing studies. This higher estimate does not mean that many Lyme disease cases go untreated, says the CDC, only that they may go unreported to state and federal public health laboratories. Low disease estimates from under-reporting can create an inaccurate picture of the scope of a public health problem such as this, especially when the incidence may be so much higher than previously thought. Better estimates obtained from the ongoing studies can help increase awareness of the issue, providing additional incentive for the general public, government, and medical community to focus on this disease and its prevention.

Post-Treatment Lyme Disease Syndrome
For some people with Lyme disease, symptoms of fatigue, pain, or joint and muscle aches persist even after treatment with antibiotics. For a small percentage of cases, these symptoms can last over 6 months. This is known as Post-Treatment Lyme Disease Syndrome (PTLDS). The exact cause of PTLDS is unknown. PTLDS is sometimes mistakenly referred to as chronic Lyme disease. Research is ongoing to better understand the cause of this syndrome. For more information, see the CDC web page on PTLDS.

Accordion Title
About Lyme Disease
  • Signs and Symptoms

    Lyme disease occurs in stages, with the early infection confined to the area around the tick bite and progressing to early disseminated and then to late Lyme disease.

    Early signs and symptoms can develop from 3 to 30 days after the tick bite and may include:

    • Characteristic rash at the site of the tick bite: one of first symptoms is usually a rash that appears a few days to a month after the bite (the average is about 7 days). About 70% to 80% of people infected with Borrelia burgdorferi will develop the characteristic circular rash called erythema migrans. It typically spreads outward from the bite site and may eventually measure up to 12 inches (30 centimeters) or more across. It may resemble a "bulls-eye" and may feel warm to the touch but usually is not painful or itchy. Some people may develop multiple red rashes and others may not have, or remember having, a rash. Note that it is common to see a small bump or redness that develops soon after a tick bite that may look like a mosquito bite. However, this bump or redness generally goes away in one or two days and is not a sign of Lyme disease. (See Related Images for examples of erythema migrans.)
    • Headache
    • Fatigue
    • Fever and chills
    • Muscle and joint aches
    • Swollen lymph nodes


    Borrelia mayonii seems to produce other symptoms, including nausea and vomiting, and may cause a rash that is more spread out (diffuse) and lacks the bull's eye target appearance.

    If Lyme disease is left untreated, additional signs and symptoms may develop several days to months after a tick bite, including:

    • Muscle and joint pain (may be intermittent)
    • Facial weakness and paralysis (Bell's palsy)
    • Numbness and pain in arms and legs
    • Neck stiffness and severe headaches (meningitis)
    • Chest pain and irregular heart beat (rare)
    • Eye irritation, redness, pain, and blurred vision (rare)
    • Intermittent arthritis with joint pain and swelling, especially in larger joints like the knees
    • Memory loss, difficulty concentrating, and changes in sleep patterns
    • Spells of dizziness or shortness of breath
    • Shooting pains, numbness, or tingling in the hands or feet
    • Inflammation of the brain and/or spinal cord
  • Tests

    A healthcare practitioner may diagnose Lyme disease if you:

    • Have signs and symptoms, such as the presence of an erythema migrans (EM) or "bull's-eye" rash
    • Have been bitten by a tick and/or live in or visited an area where Lyme disease is most commonly found


    In cases where history and symptoms are sufficient to diagnose Lyme disease, a laboratory test is not usually ordered.

    Lyme disease testing may be ordered when you have signs and symptoms that suggest you have the infection. The CDC does not recommend Lyme disease testing for people who do not have any symptoms.

    The preferred test is a blood test to detect two classes of antibodies produced by the body in response to a Borrelia infection:

    • Borrelia IgM (immunoglobulin M) antibodies can usually be detected in the blood about two to three weeks after infection. IgM levels increase and then peak at about six weeks and then begin to decline.
    • IgG (immunoglobulin G) antibodies cannot be detected until several weeks after infection. Levels peak about four to six months later and may remain at high levels for several years.


    The CDC recommends that two different methods be used to detect these antibodies and to confirm a diagnosis of Lyme disease.

    • The initial test may use methods such as an enzyme immunoassay (EIA) or immunofluorescence (IFA) method to measure Borrelia IgM and/or IgG antibodies. The initial test is intended to be very sensitive so that it will detect as many cases of Lyme disease as possible. However, it may be positive with infections caused by other bacteria similar to Borrelia, such as a different tick-borne disease or syphilis, or in other conditions such as an autoimmune disorder (e.g., lupus).
    • The CDC recommends that any positive or indeterminate results from an initial test be followed by a second test, called a Western blot that detects specific antibodies to multiple antigens, to confirm the initial findings.


    If you have symptoms that suggest your central nervous system is affected (meningitis), then testing may be performed on a sample of cerebrospinal fluid (CSF).

    In special cases, PCR (polymerase chain reaction) testing may be performed on a sample because it is a more sensitive way of detecting an infection with Borrelia. However, this is not an FDA cleared or approved test method and it is not widely available. The CDC does not currently recommend PCR testing for the diagnosis of Lyme disease.

  • Treatment

      Lyme disease is usually treated with antibiotics taken by mouth for 2-4 weeks. Some people with severe infections may require antibiotics administered through a vein (intravenous). In most cases, those with Lyme disease recover rapidly and completely. In some cases, especially with late-stage Lyme disease, some joint pain and nerve damage may persist. For more on Lyme disease treatment, see this CDC web page.

    • Prevention

      Currently, there is no vaccine available to prevent Lyme disease, but standard precautions to avoid exposure to ticks and tick bites can greatly reduce the risk of becoming infected. These include:

      • Wearing light-colored long-sleeved shirts and pants
      • Tucking pant legs into socks
      • Wearing closed shoes
      • Avoiding wooded and grassy areas, especially in spring and early summer, walking in the center of trails
      • Using a tick repellant that contains 20-30% DEET (N, N-diethyl-m-toluamide) or permethrin
      • Checking for ticks after spending time outside
      • Removing ticks as soon as they are found
      • Pets should also be routinely checked for ticks.
    View Sources

    Sources Used in Current Review

    Meyerhoff, J. et. al. (2018 November 14, Updated). Lyme Disease. Medscape Rheumatology. Available online at https://emedicine.medscape.com/article/330178-overview. Accessed March 2019.

    Vyas, J. et. al. (2018 January 31, Updated). Lyme disease. MedlinePlus Medical Encyclopedia. Available online at https://medlineplus.gov/ency/article/001319.htm. Accessed March 2019.

    (2018 June, Updated). Borrelia Species - Lyme Disease and Borrelia hermsii. ARUP Consult. Available online at https://arupconsult.com/content/borrelia-species. Accessed March 2019.

    (2017 December 1, Updated). Why is CDC concerned about Lyme disease? Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/lyme/why-is-cdc-concerned-about-lyme-disease.html. Accessed March 2019.

    Brooks, M. (2018 November 14). US Had Record Number of Tick-borne Diseases in 2017. Medscape Medical News. Available online at https://www.medscape.com/viewarticle/904895. Accessed March 2019.

    (2018 July 19, Updated). Centers for Disease Control and Prevention. Lyme Disease Frequently Asked Questions (FAQ). Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/lyme/faq/index.html. Accessed March 2019.

    (2018 October 15, Updated). Lyme Disease. Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/lyme/. Accessed March 2019.

    (2018 November 16, Reviewed). Lyme Disease. National Institute of Allergy and Infectious Diseases. Available online at https://www.niaid.nih.gov/diseases-conditions/lyme-disease. Accessed March 2019.

    Sources Used in Previous Reviews

    Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

    Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

    Wormser GP, 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. Clinical Infectious Diseases 2006;43:1089–1134. Available online at http://www.journals.uchicago.edu/doi/full/10.1086/508667?cookieSet=1. Accessed June 2009.

    (May 1, 2008) Press Release: Agreement Ends Lyme Disease Investigation by Connecticut Attorney General. Available online at http://www.idsociety.org/Content.aspx?id=11182. Accessed June 2009.

    Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 632-633.

    Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 1538.

    Forbes, B. et. al. (© 2007). Bailey & Scott's Diagnostic Microbiology, 12th Edition: Mosby Elsevier Press, St. Louis, MO. Pp 537-539.

    (Modified 2009 January 27). Learn About Lyme Disease. Centers for Disease Control and Prevention [On-line information]. Available online at http://www.cdc.gov/ncidod/dvbid/lyme/. Accessed March 2009.

    (Reviewed 2008 October 7). Lyme Disease Diagnosis. Centers for Disease Control and Prevention [On-line information]. Available online at http://www.cdc.gov/ncidod/dvbid/lyme/ld_humandisease_diagnosis.htm. Accessed March 2009.

    Editorial staff (Updated 2008 May). Lyme Disease. Familydoctor.org [On-line information]. Available online at http://familydoctor.org/online/famdocen/home/common/infections/common/bacterial/257.printerview.html. Accessed March 2009.

    (2007 June 27). Beware of Ticks … & Lyme Disease. U.S. Food and Drug Administration [On-line information]. Available online at http://www.fda.gov/consumer/updates/lymedisease062707.html. Accessed March 2009.

    (Reviewed 2008 October 8). Lyme Disease Treatment and Prognosis Centers for Disease Control and Prevention [On-line information]. Available online at http://www.cdc.gov/ncidod/dvbid/lyme/ld_humandisease_treatment.htm. Accessed March 2009.

    Mayo Clinic Staff (2008 May 2). Lyme disease. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/print/lyme-disease/DS00116/METHOD=print&DSECTION=all. Accessed March 2009.

    (2008 July). Lyme Disease - The Facts The Challenge. National Institute of Allergy and Infectious Diseases, National Institute of Arthritis and Musculoskeletal and Skin Diseases [On-line information]. PDF available for download at http://www3.niaid.nih.gov/topics/lymeDisease/PDF/LymeDisease.pdf. Accessed March 2009.

    (© 2009). Lyme Disease: A Patient's Guide. American College of Physicians [On-line information]. Available online at http://www.acponline.org/clinical_information/resources/lyme_disease/patient/. Accessed March 2009.

    Edlow, J. (Updated 2008 December 12). Tick-Borne Diseases, Lyme. Emedicine [On-line information]. Available online at http://emedicine.medscape.com/article/786767-overview. Accessed March 2009.

    (Updated 2011 March 29). Lyme Disease. National Institute of Allergy and Infectious Diseases [On-line information]. Available online at http://www.niaid.nih.gov/topics/lymedisease/understanding/pages/intro.aspx. Accessed June 2012.

    Mayo Clinic Staff (Updated 2011 February 16). Lyme Disease MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/print/lyme-disease/DS00116/METHOD=print&DSECTION=all. Accessed June 2012.

    Cook, J. et. al. (Updated 2011 June). Borrelia burgdorferi - Lyme Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/LymeDisease.html?client_ID=LTD. Accessed June 2012.

    (Updated 2012 March 7). Lyme Disease Frequently Asked Questions (FAQ). Centers for Disease Control and Prevention [On-line information]. Available online at http://www.cdc.gov/lyme/faq/index.html. Accessed June 2012.

    Meyerhoff, J. (Updated 2011 September 27). Lyme Disease. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/330178-overview. Accessed June 2012.

    Zieve, D. and Eltz, D. (Updated 2011 August 26). Lyme disease. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001319.htm. Accessed June 2012.

    (2011 Winter) The Alarming Spread of Lyme. LymeMDNews v4 (1). Encyclopedia [On-line information]. PDF available for download at http://www.lymemd.org/pdf/LymeMD_newsletter_spring_2011.pdf. Accessed June 2012.

    Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 652-653.

    Centers for Disease Control and Prevention. Post-Treatment Lyme Disease Syndrome. Available online at http://www.cdc.gov/lyme/postLDS/index.html. Accessed July 2012.

    Centers for Disease Control and Prevention. Reported cases of Lyme disease by state or locality, 2003-2012. Available online at http://www.cdc.gov/lyme/stats/chartstables/reportedcases_statelocality.html. Accessed June 2014.

    Centers for Disease Control and Prevention. Lyme Disease Data. Available online at http://www.cdc.gov/lyme/stats/index.html. Accessed June 2014.

    (February 5, 2016) Identification of a novel pathogenic Borrelia species causing Lyme borreliosis with unusually high spirochaetaemia: a descriptive study. The Lancet Infectious Diseases. Available online at http://www.thelancet.com/journals/laninf/article/PIIS1473-3099(15)00464-8/abstract. Accessed March 16, 2016.

    Centers for Disease Control and Prevention. Press Release: New Lyme-disease-causing bacteria species discovered. February 8, 2015. Available online at http://www.cdc.gov/media/releases/2016/p0208-lyme-disease.html. Accessed March 16, 2016.

    Meyerhoff, J. and Zaidman, G. (2015 January 22, Updated). Lyme Disease. Medscape Drugs & Disease [On-line information]. Available online at http://emedicine.medscape.com/article/330178-overview. Accessed 07/18/15.

    Vyas, J. (2014 February 3, Updated). Lyme Disease. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001319.htm. Accessed 07/18/15.

    (2014 March, Updated). Lyme Disease. FamilyDoctor.org. [On-line information]. Available online at http://familydoctor.org/familydoctor/en/diseases-conditions/lyme-disease.printerview.all.html. Accessed 07/18/15.

    (2015 July 01, Updated). A History of Lyme Disease, Symptoms, Diagnosis, Treatment, and Prevention. National Institute of Allergy and Infectious Diseases. [On-line information]. Available online at http://www.niaid.nih.gov/topics/lymeDisease/Pages/history.aspx. Accessed 07/18/15.

    Couturier, M. and Hillyard, D. (2015 May, Updated). Borrelia burgdorferi - Lyme Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/LymeDisease.html?client_ID=LTD. Accessed 07/18/15.

    Wright, W. (2012 June 1). Diagnosis and Management of Lyme Disease. American Family Physician 85(11):1086-1093. [On-line information]. Available online at http://www.aafp.org/afp/2012/0601/p1086.html. Accessed 07/18/15.

    Ben-Joseph, E. (2013 July, Reviewed). Lyme Disease. Nemours Foundation [On-line information]. Available online at http://kidshealth.org/teen/infections/skin_rashes/lyme_disease.html. Accessed 07/18/15.

    Pagana, K. D., Pagana, T. J., and Pagana, T. N. (© 2015). Mosby's Diagnostic & Laboratory Test Reference 12th Edition: Mosby, Inc., Saint Louis, MO. Pp 613-614.

    (March 4, 2015) Centers for Disease Control and Prevention. How many people get Lyme disease? Available online at http://www.cdc.gov/lyme/stats/humancases.html. Accessed October 2015.