Lyme Disease: Laboratory Testing for Diagnosis 

Lyme disease is the most common tick-borne disease in the United States.1,2 The disease is mainly caused by the bacterial species Borrelia burgdorferi and is primarily transmitted by deer ticks (Ixodes scapularis or I pacificus).1,2 In its early stages, Lyme disease is easily treatable with antibiotics in most persons; however, advanced disease is associated with marked morbidity and complications.2 This article discusses Lyme disease, its complications, and the importance of early diagnosis, laboratory testing, and treatment. 

Epidemiology of Lyme Disease
Lyme disease is most common among children and middle-aged adults.2 The exact incidence of Lyme disease is unknown because cases are largely unreported.1 In 2019, about 35,000 confirmed and probable cases of Lyme disease were reported to Centers for Disease Control and Prevention (CDC).1 However, insurance records suggest that 300,000 to 476,000 Americans may be diagnosed and treated for Lyme disease each year.3 While insurance records may overestimate case numbers owing to pre-emptive treatment of some patients, they highlight the large burden on the healthcare system. 

The geographic distribution of high-incidence Lyme disease areas appears to be expanding.1 Cases are heavily centered in New England and the Mid-Atlantic. However, they are also found in Wisconsin, Minnesota and, to a lesser extent, other states in the Great Lakes and Pacific Coastal regions.1 Other tick-borne diseases may be distinguished by geographic distribution, symptoms, and/or laboratory tests (see Sidebar).4-8

Stages and Symptoms of Lyme Disease
In general, the clinical presentation of Lyme disease occurs in 3 stages: early localized, early disseminated, and late.

Early Localized Disease
Symptoms of early localized disease include fever, myalgia, headache, nausea, fatigue, and erythema migrans (Figure) beginning 3 to 30 days after the tick bite.2,9 Erythema migrans is a round skin lesion ≥5 cm in diameter that may appear in a "bulls-eye" pattern, and occurs in approximately 80% of infected persons.9 If erythema migrans is not present, the differential diagnosis may include other tick-borne diseases such as Borrelia miyamotoi disease, which is often misdiagnosed as Lyme disease owing to overlapping symptoms.10
Figure.  Erythema migrans of the posterior right shoulder in a patient with Lyme disease. Image courtesy of the CDC Public Health Library.

Early Disseminated Disease
The early disseminated stage of Lyme disease is characterized by symptoms from 2 weeks to months after the tick bite. Annular skin lesions smaller than those of erythema migrans may be the first sign of early disseminated disease; however, some individuals with Lyme disease do not develop these additional lesions.2,9 Nonspecific symptoms include severe headaches and neck stiffness, facial palsy, arthritis, malaise, fatigue, and migratory pain in joints, bones, and muscles.9 Atrioventricular heart block, sometimes with myopericarditis, can occur.2,9

Late-Stage Disease
Late-stage disease is defined as symptoms occurring from months to years after the tick bite. Fatigue and prolonged chronic arthritis are common nonspecific symptoms. Severe complications include encephalopathy, polyneuropathy, lymphocytic meningitis, and lymphocytoma.2,9

Recognized Complications of Lyme Disease
Recognized complications of late-stage disease include Lyme carditis,11 neurologic Lyme disease,12 and Lyme arthritis.13

Lyme carditis occurs when B burgdorferi infects the heart.11,14 The condition manifests as myocarditis and/or atrioventricular nodal conduction abnormalities.11,14 Carditis can occur any time after the early localized stage and can be fatal. Symptoms include light-headedness, fainting, shortness of breath, heart palpitations, and chest pain.11 The condition is treated with oral or intravenous antibiotics, with the choice of antibiotic and dosage based on the degree of heart block.11 Importantly, the CDC recommends that patients with suspected Lyme carditis should be hospitalized for cardiac monitoring and treated with antibiotics prior to laboratory confirmation of Lyme disease.2,11

Neurologic Lyme disease occurs when B burgdorferi infects the peripheral or central nervous system (CNS).12,14 Cranial nerve involvement can result in unilateral or bilateral facial palsy, and peripheral nerve involvement can cause radiculoneuropathy that can manifest as numbness, tingling, shooting pain, or weakness in the arms or legs.12 Though not common in the United States, CNS involvement can result in meningitis or encephalitis with associated cognitive dysfunction and memory loss.14 The condition is treated with antibiotics based on the degree of neurological involvement.12

Lyme arthritis, which occurs when B burgdorferi infects the joints, is a common complication; more than 1 in 4 Lyme disease cases reported to the CDC include Lyme arthritis as a clinical manifestation.13 The condition typically develops 1 to a few months after infection and is characterized by the swelling of 1 or more joints.13 The knee is the most commonly affected, but other large joints such as the shoulder can be involved. If untreated, Lyme arthritis can lead to permanent joint damage.13,14 Although most patients respond to a course of oral antibiotic treatment of 28 days, some patients are less responsive.2 Patients with no or minimal response may require a 2- to 4- week course of intravenous antibiotics, with referral to a rheumatologist if treatment failure persists.
Diagnosis of Lyme Disease
Diagnosis of early localized Lyme disease may be made based on the presence of erythema migrans alone, if there is a history of exposure in an area where Lyme disease is endemic.2 If lesions are atypical and a diagnosis is not clear, laboratory testing should be performed.2,15

Serological testing for Lyme disease primarily uses US Food and Drug Administration (FDA)–cleared tests for immunoglobulin M (IgM) or immunoglobulin G (IgG) antibodies to B burgdorferi, guided by symptoms and the timeline of exposure.2,15,16 Two to 4 weeks following the tick bite, positive antibody results for IgM and negative results for IgG indicate early infection. Testing performed >1 month after infection will typically be positive for IgG and negative for IgM.2,15,16 However, this result does not differentiate between active or past infection.2,15,16 Positive IgM results >1 month are unlikely to reflect active disease unless IgG is also positive.2 Although IgM and IgG antibodies to B burgdorferi may persist for 10 years or more after infection, these responses do not indicate active infection.17 False-positive results can occur as a result of infection with other tick-borne diseases, some viral or bacterial infections, or autoimmune diseases.16

The CDC recommends testing for IgM or IgG using a standard (STTT) or modified (MTTT) 2-tiered test.2,15,16 An STTT uses a sensitive enzyme immunoassay (EIA) or immunofluorescence assay (IFA) as a first test, followed by a Western immunoblot assay for specimens yielding positive or equivocal results.2,15,16 An MTTT uses a second EIA in place of the Western immunoblot assay. FDA-cleared MTTTs became available in 20192,15,16 and may detect up to 30% more cases as compared to an STTT in patients with early Lyme disease.2

PCR-based testing (molecular testing) is not recommended for a primary diagnosis of Lyme disease because the organism is typically found in the peripheral circulation for a relatively brief period of time.2 However, testing for B burgdorferi DNA may be useful under certain circumstances. When Lyme arthritis is suspected, treatment decisions may require more definitive evidence of active infection than serology. 2 PCR detection of Borrelia DNA in synovial fluid, commonly from the knee, supports the diagnosis of Lyme arthritis (sensitivity, 78%; specificity, 100%).18

Management of Lyme Disease
Patients with Lyme disease are treated with antibiotics.2 The choice of antibiotic and the duration of treatment depend on the stage of Lyme disease, associated complications, and the response to treatment.2,11-13 Prophylaxis or serologic testing after a tick bite is usually not indicated in areas where less than 20% of ticks are infected; however, the CDC recommends laboratory testing, including tick identification, in areas where infected ticks are endemic.2,16

Post-Treatment Lyme Disease Syndrome
Most patients with Lyme disease respond to appropriate treatment within 2 to 4 weeks.19 However, about 10% of patients have symptoms that last for more than 6 months after completing treatment, including persistent pain, fatigue, and difficulty thinking.19,20 The cause of this “post-treatment Lyme disease” syndrome is unknown, and no proven treatment is available.19,20 While the pathogenesis of the condition is incompletely understood, an auto-immune response is suspected.19,20 In most chronically symptomatic patients, symptoms eventually resolve over months to years.19,20
Other Diseases Transmitted by Ticks 

Different tick-borne diseases are endemic to different geographic regions of the United States.4,5 Examples are listed below, and a complete list can be viewed at

Knowledge of the geographic region where the tick bite occurred is important for making a diagnosis as many tick-related illnesses have overlapping symptoms.6 For example, fever is common to most tick-borne diseases as are symptoms such as headache, fatigue, and muscle aches.6 Although diseases such as Lyme disease, RMSF, and ehrlichiosis have characteristic rashes, they may not be present in all patients.6 In addition, Ixodes ticks may transmit other pathogens in addition to B  burgdorferi, including Babesia, Anaplasma, other Borrelia species, and viruses.7 Thus, serological testing is important for the differential diagnosis of Lyme and tick-borne diseases.4,8
How the Laboratory Can Help

Quest Diagnostics offers FDA-cleared, CDC-recommended STTT and MTTT for the diagnosis of Lyme disease. PCR-based molecular testing is also available for identification of B burgdorferi DNA, as well as for other common tick-borne diseases. In addition, molecular and antibody panels are available to assist in the diagnosis of Lyme disease and differential diagnosis of other tick-borne diseases. 

Additional information is available at  

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  1. Recent surveillance data. Centers for Disease Control and Prevention. Reviewed April 29, 2021. Accessed June 4, 2021.
  2. Lantos PM, Rumbaugh J, Bockenstedt LK, et al. Clinical practice guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis, and Treatment of Lyme Disease. Arthritis Care Res (Hoboken). 2021;73(1):1-9. doi:10.1002/acr.24495
  3. How many people get Lyme disease? Centers for Disease Control and Prevention. Reviewed January 13, 2021. Accessed May 12, 2021.
  4. Diseases transmitted by ticks. Centers for Disease Control and Prevention. Reviewed April 2, 2020. Accessed April 7, 2021.
  5. Centers for Disease Control and Prevention. Tickborne Diseases of the United States: A Reference Manual for Health Care Providers. 4th ed. Centers for Disease Control and Prevention; 2017. Accessed April 20, 2021.
  6. Symptoms of tickborne illness. Centers for Disease Control and Prevention. Reviewed January 10, 2019. Accessed May 12, 2021.
  7. Murray TS, Shapiro ED. Lyme disease. Clin Lab Med. 2010;30(1)311-328. doi:10.1016/j.cll.2010.01.003
  8. What you need to know about Borrelia mayonni. Centers for Disease Control and Prevention. Reviewed September 12, 2019. Accessed April 20, 2021.
  9. Signs and symptoms of untreated Lyme disease. Centers for Disease Control and Prevention. Reviewed January 15, 2021. Accessed April 20, 2021.
  10. Telford SR III, Goethert HK, Molloy PJ, et al. Borrelia miyamotoi disease: neither Lyme disease nor relapsing fever. Clin Lab Med. 2015;35(4):867-882. doi:10.1016/j.cll.2015.08.002
  11. Lyme carditis. Centers for Disease Control and Prevention. Reviewed October 26, 2020. Accessed April 20, 2021.
  12. Neurologic Lyme disease. Centers for Disease Control and Prevention. Reviewed October 23, 2020. Accessed April 20, 2021.
  13. Lyme arthritis. Centers for Disease Control and Prevention. Reviewed October 26, 2020. Accessed April 20, 2021.
  14. Schoen RT. Lyme disease: diagnosis and treatment. Curr Opin Rheumatol. 2020;32(3):247-254. doi:10.1097/BOR.0000000000000698
  15. Mead P, Petersen J, Hinckley A. Updated CDC recommendation for serologic diagnosis of Lyme disease. MMWR Morb Mortal Wkly Rep. 2019;68(32):703. doi:10.15585/mmwr.mm6832a4
  16. Diagnosis and testing. Centers for Disease Control and Prevention. Reviewed November 20, 2019. Accessed April 20, 2021.
  17. Kalish RA, McHugh G, Granquist J, et al. Persistence of immunoglobulin M or immunoglobulin G antibody responses to Borrelia burgdorferi 10-20 years after active Lyme disease. Clin Infect Dis. 2001;33(6):780-785. doi:10.1086/322669
  18. Steere AC. Treatment of Lyme arthritis. J Rheumatol. 2019;46(8):871-873. doi:10.3899/jrheum.190320
  19. Post-treatment Lyme disease syndrome. Centers for Disease Control and Prevention. Reviewed November 8, 2019. Accessed April 20, 2021.
  20. Ścieszka J, Dąbek J, Cieślik P. Post-Lyme disease syndrome. Reumatologia. 2015;53(1):46-48. doi:10.5114/reum.2015.50557

Content reviewed 6/2021