Services of the Lyme Borreliosis Unit

See here for details of the Lyme Borreliosis Unit

Laboratory diagnosis

The most commonly used tests look for antibodies to Borrelia burgdorferi (Bb), the organism that causes LB. An infected person’s immune system produces antibodies in response to Bb infection, just one of the mechanisms used by the body to fight infection.The antibody response takes several weeks to reach a detectable level, so antibody tests in the first few weeks of infection may be negative. It is rare for patients to have negative antibody tests in longstanding infections. [1, 2]
The antibody test systems used in the Lyme Borreliosis Unit (LBU) follow the two-stage system currently recommended by European and American authorities, in which samples are tested in a sensitive screening test system [3]. Sensitive screening tests are used because they can detect low levels of antibodies; but they have the disadvantage of producing occasional false positive results in samples from some patients with other conditions. These include glandular fever, syphilis, other infections, rheumatoid arthritis, other autoimmune conditions and some neurological conditions. Those which give reactive or equivocal screening test reactions are then tested in a more detailed system, called immunoblot or western blot, to confirm the presence of Bb-specific antibodies. These second stage tests allow laboratory workers to give a more accurate assessment of the presence of Bb antibodies. The significance of any result, negative or positive, should be interpreted carefully by clinicians in the light of the patient’s clinical presentation and tick exposure risk history.
All the antibody test kits routinely used in the LBU have been fully validated and CE marked. Those available for use in the USA as well as the EU are also US FDA-approved. All kits are used according to manufacturers’ instructions and quality control procedures observed.
Other tests that can be used include detection of Bb DNA using polymerase chain reaction (PCR).  This type of molecular test is useful in certain circumstances, especially on joint fluids in suspected Lyme arthritis, and on samples from suspected skin infections. It is less helpful than antibody testing of CSF and is of little value in testing blood samples, as borreliae are rarely present in the bloodstream after the early stage of infection.  PCR tests for Bb DNA are performed in the Southampton HPA laboratory’s Molecular Diagnostic Unit (MDU), which has wide experience in providing an extensive range of molecular diagnostics tests for many regional specialist units, including bone marrow transplant and intensive care.

Clinical discussions

General practitioners and specialists frequently contact the LBU to discuss options for investigation of patients with difficult clinical presentations, or to discuss treatment options. The LBU has a range of tests that can be applied in cases of diagnostic uncertainty. Staff members have contacts with experienced physicians in a variety of specialties, including infectious diseases, neurology, rheumatology and paediatrics, based throughout the country, and they frequently recommend consultations with appropriate specialists from this network.

Epidemiological functions

The LBU works closely with the Zoonoses Section of Public Health Wales Communicable Disease Surveillance Centre (CDSC) in Cardiff, to whom all positive test results are reported. The LBU has provided reference services to all England and Wales laboratories since 2000, and this has helped to develop a much more complete reporting system. Prior to 2000 other laboratories also provided reference services, but reporting of positive tests was voluntary and incomplete.

Enhanced Surveillance

An enhanced surveillance system, using data obtained by questionnaires sent to clinicians, was implemented by the LBU and CDSC between 1996 and 2003. This gave much better epidemiological information than previously available, thanks to efforts of the many clinicians who participated. A new electronic data management system was introduced in 2006 to ensure that anonymised reporting was as complete as possible. It is recognised that figures derived from laboratory reports underestimate the true incidence of LB in England and Wales, but it is possible to follow trends on a year-to-year basis through the robust laboratory reporting system now in place.

International liaison

The LBU works with experts in the USA, Germany, Canada, other countries and the EUCALB initiative on a range of issues which include further improvements in laboratory diagnostic tests, and reviewing evidence-based criteria for diagnosis and treatment. There is considerable concern internationally about the use of unvalidated, unorthodox and scientifically implausible laboratory tests leading to misdiagnosis and the use of potentially dangerous treatments [4-7].

References

1. Stanek G, Strle F. Lyme borreliosis. Lancet 2003; 362(9396): 1639-47 http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2803%2914798-8/fulltext
2. Steere A. Lyme disease. New Eng J Med 2001;345(2):115-25
3. Recommendations for Test Performance and Interpretation from the Second National Conference on Serologic Diagnosis of Lyme Disease. MMWR 1995; 44(31): 590-1 http://www.cdc.gov/mmwr/preview/mmwrhtml/00038469.htm
4. Caution regarding testing for Lyme disease. MMWR 2005; 54: 125 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5405a6.htm.
5. Duerden BI. Unorthodox and unvalidated laboratory tests in the diagnosis of Lyme borreliosis and in relation to medically unexplained symptoms. Department of Health, London, UK, 2006.
http://www.dh.gov.uk/assetRoot/04/13/89/17/04138917.pdf
6. FDA Warns Consumers and Health Care Providers Not to Use Bismacine, also known as Chromacine. July 21, 2006. http://www.fda.gov/bbs/topics/NEWS/2006/NEW01415.html
7. Feder HM, Johnson BB, O'Connell S, Shapiro ED, Wormser GP and the ad-hoc International Lyme Disease study group. A critical appraisal of "chronic Lyme disease". New Eng J Med. 2007;357:1422-30

Last reviewed: 18 November 2010