How do you interpret Lyme Disease Blood Tests??
Firstly, it must be stressed that Lyme Disease is NOT diagnosed on the basis of a blood test. This is because there are currently too many false negative results. A “negative” Lyme Disease blood test does not rule out a Lyme bacterial infection. Lyme Disease is a clinical diagnosis based upon previous medical history and current presenting symptoms – blood tests assist in guiding treatment, but should NOT be used for diagnosis. False positive blood test results are very rare, especially when specific Lyme Disease bands are taken into consideration.
We need to note that currently the Lyme Disease Association of Australia (LDAA) does not recommend being tested in Australia (except privately by PCR test). Research through our survey’s of Australian Lyme Disease patients (which is backed up with research overseas) has shown that the vast majority of testing for Lyme Disease is not 100% reliable, which is why Lyme Disease is a clinical diagnosis, not one based solely on blood test results. Currently most Australian Lyme Disease patients are being tested through the Igenex lab in California (www.igenex.com), the Infectolab in Germany (www.infectolab.com.au) and Australian Biologics in Sydney (www.australianbiologics.com.au). Infectolab and Igenex are specialty Lyme Disease testing laboratories and are government accredited labs, which at this time Australian Biologics is not.
Background : Why is it so hard to test for Lyme Disease? – firstly, the bacteria that causes Lyme Disease often does not reside in the blood, but rather in tissues, organs, the nervous system, and in collagen and joints, which makes it very difficult to isolate during a PCR blood test.
Secondly, the vast majority of blood tests currently do not actually test for the Lyme Disease bacteria itself, but rather the body’s immune response to it. Because of the nature of Lyme Disease and its ability to depress the immune system, we have found that the sicker the patient is, the less likely they are to return a positive result, as their body has not been able to mount a strong immune defence against the Lyme Disease bacteria.
Thirdly, there are many different strains of Lyme Disease all around the world. Currently there are 14 known genospecies of Borrelia Burgdorferi senso lato (the bacteria that causes Lyme Disease), with more being discovered every year – the Western Blot blood test, tests for 2 of these strains. Currently the strain of Borrelia that causes Lyme Disease in Australia has not been isolated, and so it is not possible to accurately test for the native Australian strain of Lyme Disease.
Fourthly, due to medical politics in the USA (which affects patients in Australia), it is difficult to interpret Lyme Disease testing based on laboratory reporting. This is because the Infectious Diseases Society of America (IDSA) has recommended that Lyme Disease testing follow a two tier testing procedure, that firstly tests patients using an ELISA test, and if this is positive, that it then be further confirmed via a Western Blot blood test. The problem with this, is that the ELISA is insufficiently sensitive to test for Lyme Disease [Trevejo R, JID 1999; 179:931–8.] and many infected patients don’t get referred on for the Western Blot test. Also, the US Centre for Disease Control (CDC) has stipulated that certain “bands” in the Western Blot test must be positive in order for a Lyme test to be declared positive – the problem is that these bands were chosen for statistical, rather than diagnostic criteria. For example, the most specific bands for Lyme Disease (bands 31 and 34) were excluded from the CDC criteria because they were used to create the Lyme Disease vaccine (which is no longer available), thus eliminating valuable testing data. If you have not received the Lyme Disease Vaccine and you test positive (“+”) or indeterminate (“IND”) to bands 31 and 34, you probably have Lyme Disease. The CDC testing criteria actually includes a number of bands which are not specific to Lyme Disease, which increases the chances of a false negative, but only if the CDC criteria for test reporting is used.
What is the difference between “+”, “++”, “+++” and “IND”? These are the level to which the laboratory technician can see the immune response to the specific part of the bacteria. Both “++” and “+++” results are very rare, and show a strong immune response to the Lyme Disease bacteria. If a patients immune response is compromised (as it is in most Lyme Disease patients and particularly in patients with neurological, late stage or severe Lyme Disease), a “IND” result is a weak positive immune response to Lyme Disease and should be treated as a positive result. After treatment, many patients who are retested return stronger results, as their immune system has been able to mount a more effective response against the Lyme Disease bacteria.
What is the difference between the Western Blot IgG and IgM tests? – IgM is generally regarded as the body’s response to recent exposure to Lyme Disease. IgG is generally regarded as the body’s response over time (ie. longer term) to Lyme Disease. Because the immune system is compromised in Lyme Disease, often the IgG and IgM responses can become mixed up.
When should I test for Lyme Disease? It takes the body 6 weeks to 6 months to make antibodies to Lyme Disease – therefore testing straight after a tick bite is not recommended. Also, patients with late stage Lyme Disease will have an impaired immune response due to the interaction by the Lyme Disease bacteria in depressing the immune system, making testing unreliable as well.
So, how do I interpret the Lyme Disease Blood test results??
Currently there are 9 identified bands specific to Lyme Disease – 18, 23-25, 31, 34, 37, 39, 83 and 93. A “+” or “IND” to one of these bands is considered a positive result. A “+” or “IND” to two or more of these bands is considered a strong positive result.
Other bands on the Western Blot report such as 22, 28, 30, 41, 45, 58, 66, & 73, all add significant weight to the result, but at this stage are not necessarily considered as absolute specific for Lyme bacteria.
NOTE : It must be stressed that a Lyme Disease diagnosis is not based on a blood test result, but is rather based on medical history and current presenting symptoms – blood tests can assist in diagnosis, but should not be used to base a diagnosis on. Also, almost all Lyme Disease patients have co-infections such as Ehrlichia, Rickettsia, Babesia, Bartonella, Mycoplasma Fermentans, Chlamydia Pneumonia, etc – these have their own testing and diagnostic problems, but should be considered in the diagnosis and treatment of a patient with Lyme Disease.
For more information regarding the bands
31 (also written as 31kDa) – is the outer surface protein A (ospA) – this is a classic Lyme Disease band, used in the Lyme Disease vaccine
34 (also written as 34kDa) – this is the outer surface protein B (ospB) – this is also a hallmark Lyme Disease antibody, but is excluded from CDC criteria.
23-25 (also written as 23-25 kDa) – these are the outer surface protein C. Patients that have a 31 or 34, or 23-25 band have a 97% response rate to the correct antibiotic treatment in conjunction with correct treatment for co-infections.