• Tests are used to help confirm a diagnosis of Lyme disease when a doctor is in doubt.
  • The tests used in the UK are as useful and accurate as those officially used in other countries.
  • However, it is possible for some people with Lyme disease to test negative; see more detail below. More research is needed.
  • There is no routine test that can reliably distinguish between a past, cured infection and a current one.
  • Because of the uncertainties some “alternative” providers offer unproven tests.
  • See this animation showing why cellular tests (used by some private laboratories) are not worth spending money on.
  • A test is not needed if a patient has a typical Lyme disease rash.
  • A review by respected European scientists concluded “The challenge for clinicians is to deal with the uncertainties of imperfect laboratory tests.”[12]

Blood tests

The main type of test is a blood test which looks for antibodies to the bacteria that cause Lyme disease. This is known as serology. If antibodies have not developed sufficiently, it is possible for these tests to be negative despite active infection. Antibodies can persist for years in treated, asymptomatic patients (those with no symptoms), so positive serology does not always indicate active disease.

The NICE Guideline [1] states “Diagnose and treat Lyme disease without laboratory testing in people with erythema migrans.” Erythema migrans is the typical rash of Lyme disease.

In the UK, as in the rest of Europe, the usual method of blood testing is through a 2 tier system. A blood sample is sent to the local laboratory with which the GP surgery or hospital has a contract for laboratory services.

Tier 1 – An EIA or ELISA screening test is used and if this result is borderline or positive, then the sample is sent on to a specialist reference laboratory for confirmatory testing specific to Lyme disease.

Tier 2 – the tests carried out at the reference laboratory will include an immunoblot. The aim of this second tier test is to confirm Lyme disease and identify any false positive Tier 1 results (see following section: Is the blood test always right?)

The UK Health Security Agency provides further information on Lyme disease diagnostic services for health professionals and for patients.

Is the blood test always right?

No, but we do not know how often it is wrong in the UK: there have been no studies.

False positive EIA tests (not confirmed by the immunoblot test) can be caused by cross reactions in cases of syphilis, some other bacterial infections and Epstein Barr virus (EBV) infection.[8]

The possible reasons for a negative test in a person who genuinely has Lyme disease are:

  1. The test was carried out too early. Although antibodies may have developed sufficiently in the first 6 weeks, it can take longer and this is why an erythema migrans rash should be treated immediately. There is no point in delaying treatment to wait for a positive test to develop as early treatment is likely to be more effective.
  2. The early immune responses fluctuates, as found by a German study[2], so any early test is a “snapshot” which may be positive or negative.
  3. The person had antibiotics, or drugs suppressing the immune system, around the time of infection, possibly for another condition. These may reduce or even stop the antibody response so that a positive test does not develop. [9] This can happen if antibiotics are given for something else (e.g. as preventative medicine against Malaria  or because of misdiagnosis of the rash as cellulitis). In the case of drugs suppressing the immune system, such as steroids, this might occur if a patient presents with suspected polymyalgia or a facial palsy not recognised as due to Lyme disease. It can also happen if a person was having some cancer treatment.
  4. The person was infected by a strain of the bacterium that produces antibodies which are not recognised by the test. This is under-researched and it is not known how common this is.
  5. The person has a slow or altered immune response – as possibly in older people or pregnancy, but this is under-researched.

The blood tests may miss some genuine cases as research on tests tends to use only well-characterised, definite cases. The screening test in current use in the NHS was shown in a recent study [3] to be as good as, or better than, any other test in identifying all the 63 definite disseminated cases tested. However, in that research the only cases other than very early ones were those with neuroborreliosis in the spinal fluid, Lyme arthritis or Acrodermatitis (ACA). Less straightforward, but common, cases with widespread symptoms were not included. A scientific review of studies[12] found that in undefined late Lyme borreliosis, the tests were positive in about 7 or 8 out of 10 patients.

A paper analysed cases diagnosed with Lyme disease in a London hospital [4]. This reported that 11 people who had a negative screening test were thought by their doctors to have Lyme disease. Their blood was therefore sent for a Tier 2 test despite the negative Tier 1 test. 6 out of the 11 with a negative Tier 1 screening test had a positive immunoblot blot. Tests have changed since that 2010 study, but NICE recommends an immunoblot if there is a suspicion of Lyme disease [1 – para 1.2.18].

Blood tests following treatment

Repeat tests may be used following treatment if the patient continues to have symptoms or has a relapse, but the results may be inconclusive. Repeat tests may, or may not, show evidence of a rise in antibodies if there is still active disease. This may be shown on the repeat immunoblot by a new band or an increase in intensity of the bands. Although antibodies (and thus positive test results) can persist for years, there is some evidence that they decline faster in successfully treated patients than in those with remaining symptoms. [5]

However, the immunology of Lyme disease is complex and not yet fully understood. It is not yet known whether continuing symptoms are due to active disease, tissue damage or an auto-immune response and there is no test to determine this. Relapse (symptoms coming back after getting better) may be a more  clear cut sign of continuing disease.

Other types of test

Culture. This is the growing of bacteria in a laboratory from a sample of blood, cerebrospinal fluid or tissue. Borrelia are slow-growing bacteria which are very difficult to culture. This technique is not usually used outside a research laboratory.

Microscopy. This is the examination of a blood smear or tissue sample using a high definition microscope to directly detect the presence of spirochaetes (the family of bacteria to which Borrelia burgdorferi belongs). This is a lengthy and insensitive technique when used on blood because of the low numbers of Borrelia present except in very early infection. It can be done on tissue samples by an experienced researcher but  other spirochaetal diseases caused by similar looking bacteria would need to be excluded.

Focus floating microscopy [6] has been developed for detecting spirochaetes in tissue samples but this has not been used outside a research laboratory and has the practical difficulty that likely tissues must be identified and biopsied.

PCR (polymerase chain reaction). This process is used to detect the DNA of Borrelia bacteria. Because Borrelia move to body tissues very early in infection, PCR on blood and cerebrospinal fluid (CSF) is not very successful because of the low numbers of Borrelia. PCR is more useful on tissue samples such as from skin rashes, or synovial fluid from affected joints. There has been some research into PCR on urine, but the results are inconclusive. PCR may test positive on detecting only fragments of the bacteria which have been killed.

Spinal Fluid tests for antibodies. Cerebrospinal fluid (CSF) is obtained by a lumbar puncture and an EIA test used to confirm the presence of antibodies to Borrelia. This can give a positive result before the blood serology becomes positive. The Antibody Index compares samples of blood and CSF, taken at the same time, to determine whether there are more antibodies within the spinal fluid itself, indicating that they have not simply leaked across the blood-brain barrier. This is used to confirm Lyme neuroborreliosis. If the infection is confined to the peripheral nervous system (outside the brain and spinal cord), CSF testing may be normal. See our leaflet on Lyme Neuroborreliosis.

Spinal fluid – CXCL13. This is a relatively new test which has been shown in research to be a useful test in Lyme neuroborreliosis [11]. It is not widely available yet for general diagnostic use.

Other tests on blood. Routine tests of inflammatory markers (such as CRP, ESR), CD57 tests, blood counts etc. may be normal or abnormal and are not specific to Lyme disease.

Private tests

Private tests for Lyme disease in the UK should be done through recognised laboratories. They are available through Health Services Laboratories and Dr Sharon Marlowe. The immunoblot will be carried out at the NHS Lyme disease reference laboratory which is a good thing as the result will be believed by UK doctors. Any request for a blood test through these UK laboratories, should specify “a screening test and a Lyme disease confirmatory immunoblot” to ensure that both these tests are carried out.

There are some overseas laboratories and private clinics sometimes recommended by on-line forums which use tests that are not specific for Lyme disease (eg CD57) or not licensed for diagnosis of Lyme disease. Examples include what are known as “cellular tests”: ELISpot and LTT (Lymphocyte Transformation Test). Recent studies have shown these tests not to be useful[10] – see the animation explaining this. Results from overseas laboratories are unlikely to be believed by UK doctors. Novel tests may claim to be CE marked, but this is self-certification by the manufacturer and does not mean that the test is useful.

See our Reality Check page, or contact us if you have doubts about a test being offered to you.


  1. NICE Guideline NG95
  2. “Course of Antibody Response in Lyme Borreliosis Patients before and after Therapy” Aberer E, Schwantzer G.. ISRN Immunology. 2012;2012:1–4. See our discussion of this paper.
  3. “The Performance of Nine Commercial Serological Screening Assays for the Diagnosis of Lyme Borreliosis: A Multicenter Modified Two-Gate Design Study.” Hoeve-Bakker, B. J. A., et al. 2022. Microbiology Spectrum 10 (2).
  4. “Lyme disease in the U.K.: clinical and laboratory features and response to treatment.” Richard Dillon, Susan O’Connell, and Stephen Wright, Clinical medicine (London, England) 10, no. 5 (October 2010): 454-7,
  5. “Disappearance of specific immune response after successful therapy of chronic Lyme borreliosis.” Hassler D, Schnauffer M, Ehrfeld H, Müller E. International journal of medical microbiology : IJMM. 2004 Apr;293 Suppl:161–4.
  6. Focus floating microscopy: “gold standard” for cutaneous borreliosis? Eisendle K, Grabner T, Zelger B. American journal of clinical pathology. 2007 Feb;127(2):213–22.
  7. Diagnosis of Lyme Borreliosis.” Aguero-Rosenfeld ME, Wang G, Schwartz I, Wormser GP. Clinical Microbiology Reviews. 2005;18(3):484–509.
  8. Laboratory diagnosis of Lyme borreliosis: Current state of the art and future perspectives.” Lohr B, Fingerle V, Norris DE, Hunfeld KP. Crit Rev Clin Lab Sci. 2018;55(4):219–45.
  9. “Microbiological and serological diagnosis of Lyme borreliosis”  Wilske B, Fingerle V, Schulte-Spechtel U. FEMS Immunol Med Microbiol. 2007 Feb;49(1):13–21.
  10. Diagnostic Parameters of Cellular Tests for Lyme Borreliosis in Europe (VICTORY Study): A Case-Control Study.” Baarsma, M E et al. 2022. The Lancet. Infectious Diseases, June.
  11. “The Usefulness of Two CXCL13 Assays on Cerebrospinal Fluid for the Diagnosis of Lyme Neuroborreliosis: A Retrospective Study in a Routine Clinical Setting.” Gorkom, Tamara Van, et al. 2021. Journal of Clinical Microbiology 59 (9).
  12. “The Diagnostic Accuracy of Serological Tests for Lyme Borreliosis in Europe : A Systematic Review and Meta-Analysis .” Leeflang, Mariska M G et al. 2016. BMC Infectious Diseases 16.
  13. “Laboratory Diagnosis of Lyme Borreliosis.”Branda, John A., and Allen C. Steere. 2021. Clinical Microbiology Reviews 34 (2): 1–45.