The Lyme disease blood test is used to discover if someone who has the symptoms of a Borrelia burgdorferi infection actually has the bacteria in their bloodstream. Recent infections are much easier to detect and an IgM and IgG blood test will often be ordered as complimentary information gathering tools. This blood test does not always detect the presence of the disease, so patients that have persistent symptoms after having the test may be re-tested in a few weeks.
If any of these tests come back as positive, then other samples will be used to track the stage of the disease to determine if it has reached the chronic infection stage. At this point, a medical provider will order a Western blot test to confirm the presence of Lyme disease.
Lyme Disease is Remarkably Difficult to Diagnose
The problem with Lyme disease is that the bacteria can create a hard “shell” around themselves when inactive so that the blood tests are unable to detect them. This is especially true when the disease has reached the chronic stage. The timing of the symptoms is often used by a medical provider to establish a time line to a tick bite or exposure to a high-risk region where the disease is commonly transmitted.
Because the ticks that can spread Lyme disease are often the size of a pinhead, the ticks might not even be notice. A bulls-eye rash at the bite location is a trademark symptom of Lyme disease, but only about half of the people who are infected with the bacteria develop the rash. Once the disease reaches the chronic stage, chronic arthritis, joint pain, and neurological symptoms begin to appear, sometimes several months after the infection.
When Is the Lyme Disease Blood Test Ordered?
When someone has the signs and symptoms of Lyme disease or they live in a region that has deer ticks or black-legged ticks, then this blood test will be ordered. It will also be ordered when these symptoms occur without improvement over the course of 7-14 days by most medical providers.
- A bulls-eye rash that grows from the bite site.
- Fevers, chills, and a persistent headache that does not go away.
- Unusual and persistent fatigue that does not immediately improve.
The IgM and IgG tests are generally ordered first when Lyme disease is suspected. This is because people who have never been exposed to the bacteria that causes the disease will not have any antibodies present. If these tests are positive and followed up by a positive Western Blot test, then the chances are very good that Lyme disease is present. This is especially true if antibody levels continue to rise over time.
What Do the Test Results Mean?
Because there are three tests that are typically conducted for the Lyme disease blood test, then results can vary based on the combination of test results received. When all three tests are positive, then Lyme disease is likely. These other result combinations are usually interpreted in the following ways.
Positive IgM, Negative IgG, Negative Western Blot.
This usually indicates that the Lyme disease infection is in its early stages or that the blood test has produced a false positive result.
Negative IgM, Positive IgG, Positive Western Blot.
This is usually interpreted as having a late-stage Lyme disease infection. It may also be an indication that someone had a previous infection that has been removed from the body.
All results negative.
This is usually interpreted as there not being any infection present and that the symptoms are being caused by another issue. In some specific instances, however, it can also be seen as the antibody levels being too low to detect.
Once Lyme disease is confirmed, there will almost always be detectable levels of the bacteria which causes the disease in the IgG antibodies in their blood. This will mean that their IgG blood test results will have a standard deviation in what is considered as normal because of the presence of the disease, even if it has been effectively “cured.”
What You Should Know About Lyme Disease
If the symptoms of Lyme disease persist and there is no known cause for them, then consulting with a Lyme literate doctor may provide treatment progress. Many health insurance plans will not cover these consultations or tests, however, so proceed with caution.
For those who are treated with antibiotics, a condition called PTLD [Post Treatment Lyme Disease] occurs that mimics the symptoms of the disease for up to 6 months.
In regions where Lyme disease is not prevalent, it is usually up to the patient to insist on receiving the Lyme disease blood test. Use this guide to speak with your doctor about your concerns and discuss what the results may mean for your health.