Lyme disease testing

DISCLAIMER: Caudwell LymeCo charity shares public domain  information, which it believes to be reliable, in good faith. It should never replace the advice of a qualified physician with a license to practise medicine. If you believe any information on this website to be incorrect, you are invited to contact the charity using the Contact page.

The procedure for Lyme disease testing outlined below is currently used by the NHS in the UK.

NHS Lyme disease testing

To order an NHS blood test for Lyme disease, your GP first needs to be convinced you have a reasonable risk of having been bitten by a tick and/or that you have Lyme disease symptoms.

It takes up to 6 weeks for Lyme disease antibodies to form, and if the test is done before they have formed, it will be negative. If a test is performed too early and is negative, but the patient does have symptoms, the test should be repeated at the appropriate time to yield a more reliable result.

If you live in a Lyme endemic area where demand for Lyme disease tests is high, there may be a local laboratory which your blood may be sent to for initial testing using an ELISA test (see below). If this test is positive your blood will be sent to a national reference laboratory for repeat/confirmatory testing.

National reference laboratories

If you do not live in a Lyme endemic area your blood will be sent directly to one of the two national reference laboratories.

  • The Rare and Imported Pathogens Laboratory (RIPL) in Salisbury, England tests samples from patients in England, Wales and Northern Ireland, whilst
  • the National Lyme Borreliosis Testing Laboratory (NLBTL) at Raigmore Hospital tests samples from Scotland.

In the past, this testing was carried out by the Health Protection Agency. The HPA no longer performs Lyme disease testing although some websites still state that it does.

Local testing

Different types of ELISA test are used in different testing laboratories around the country.

The national reference laboratories do a “step two” test, first an ELISA test and then a western blot (or immunoblot) test.

At the Rare and Imported Pathogens Laboratory:

  • Step one involves a C6 antigen ELISA test. If this is negative, the patient is considered not to have Lyme disease. If this is positive or equivocal (uncertain) then a step two test is performed.
  • Step two is a Western blot test, also called an immunoblot test. If this is negative or equivocal, patients are considered not to have Lyme disease. If positive, they are given a positive Lyme diagnosis.

You can ask your doctor for printouts of both of the tests and it may be useful to do so for your own records.

Some frequently asked questions

What if my NHS Lyme disease test was negative? Does that mean I cannot have Lyme disease?

The standard Western blot test for Lyme disease, used by the NHS, has a fairly low sensitivity rate compared with tests for some other infections. This means that, if you do have Lyme disease, there is still a small possibility you could get a negative test result.

This presents problems for doctors and concern for patients, who may not feel reassured by a negative test result. Some experienced doctors may treat a patient for Lyme disease even with a negative blood test, if they feel very confident that the symptoms are caused by Lyme disease.

There are different suspected explanations of why some symptomatic  patients test negative for Lyme disease using two-tier blood testing.

  • Ticks carry a number of infections and some of them have similar symptoms to Lyme disease. Being bitten by a tick and becoming ill does not necessarily mean that the infection is Lyme disease.
  • The two-tier testing process used by the NHS looks for antibodies to the bacteria, not the bacteria itself. Some researchers think that Lyme disease suppresses the immune system so much that the antibody levels may be too low in some patients to detect using these tests.
  • People may be infected with a strain of Lyme disease which is not detected by the tests used.

Some UK doctors working for the NHS believe that the NHS tests are fully reliable, and that patients who have a negative blood test definitely do not have Lyme disease. Caudwell LymeCo would like to see more doctors becoming aware that current Lyme disease testing is not highly reliable.

Is it true that the national reference laboratory (Rare and Imported Pathogens Laboratory) at Porton Down is not nationally accredited?

This is completely untrue. This rumour surfaces periodically amongst patient groups but there is no truth in it. The national reference laboratory is CPA accredited.

Why won’t the staff at RIPL (Rare and Imported Pathogens Laboratory) discuss my Lyme test results with me?

Put simply, RIPL can discuss your results with your doctor, but it is illegal for them to discuss results with patients. Doctors who consult with patients are registered by the General Medical Council in the UK. It is a criminal offence for a doctor to practise medicine in the UK – which includes giving any advice to patients –  if he/she is not registered with the GMC.
Link to GMC register: Medical Register

Scientists who work in medical laboratories in the UK are required to hold a different type of authorisation to perform their tasks within the laboratory.

Testing in private laboratories

Some people decide to pay for Lyme disease testing at private laboratories abroad. If you decide to spend money on private testing, be prepared to pay for private treatment as well. NHS doctors only treat patients who have been diagnosed by NHS-approved laboratories.

Why won’t my GP accept my private test result?

Several private laboratories offer tests which are still regarded by the medical community as being in the research phase, and some tests are unique to the laboratory which provides them. A broad consensus has not yet been achieved in the medical community regarding how reliable some of these tests really are, or exactly how to interpret their results. Some of these tests may show great promise, and others may not. We will not know until more research is done.

Some private laboratories are not nationally accredited. Accreditation for a medical laboratory means it has been inspected by a national body and approved for, amongst other things, its ability to handle patient samples without contaminating them, its ability to organise data and paperwork so that it won’t mistakenly send someone another person’s results, and so on.

More information provides additional information on Lyme disease diagnostic tests.

Photographs by Veronica Hughes