Blood tests for Lyme disease are the usual way of confirming a diagnosis based on symptom history and clinical signs. An IgM and IgG antibody blood test for Lyme disease can normally tell if a person has been infected with Borrelia burgdorferi and, sometimes, the stage of the infection. For example, an early Lyme disease blood test immediately after a tick bite will likely give a seronegative result as the body has had little time to build up antibodies to the infectious organism. However, a test after four weeks may give a positive result for IgG antibodies but not IgM antibodies and later tests may produce the opposite results. This is due to the reactions in the body, by the immune system, to different antigens present in the saliva of the ticks, the bacteria upon first entering the body, and the later growth and replication of Lyme disease bacteria.
Timing of Lyme Disease Blood Tests
Patients who undergo a blood test for Lyme disease fairly rapidly after a tick bite may require another test at a later date if the first is negative but the symptoms persist. Those exhibiting the erythema migrans Lyme disease rash are likely to be treated with antibiotics anyway as this in itself is enough to confirm Lyme disease. In some cases patients may have a sympathetic doctor who is happy to conduct blood tests for Lyme disease during both a convalescent stage and active stage to track antibody levels. A positive ELISA Lyme disease blood test is generally followed by a Western Blot blood test for confirmation although the specificity of both of these tests, along with their sensitivity has been questioned by many Lyme advocates and medical professionals.
Coinfections of Lyme Disease and Alternative Testing
A blood test for Lyme disease may be accompanied, or even replaced, by antibody testing of a patient’s cerebrospinal fluid in cases where central nervous system dysfunction is observed. Blood tests for Lyme disease might also include a polymerase chain reaction test to determine the presence of Borrelial DNA. These tests can also be performed on cerebrospinal fluid, synovial fluid in the joints, and other body tissues. The sensitivity of PCR testing of the CSF is low however and other tests are more likely to be used.
Obtaining a Lyme Disease Blood Test
Blood tests for Lyme disease are the main way in which the condition is diagnosed but many patients struggle to convince their physician of the need for such tests, especially in states (or countries) where Lyme disease is not considered to be a problem. In these cases patients often pay a considerable sum for independent testing, by laboratories such as Igenex, that is not covered by medical insurance and may not be well regulated or rigorous enough to convince their physician to then prescribe antibiotic treatment for Lyme disease. Oftentimes testing for Lyme disease ignores the possibility of co-infections such as Babesiosis and Ehrilchiosis, which are not always eradicated by Lyme disease antibiotics and may continue to cause symptoms even as Borrelia burgdorferi spirochaetes are killed and flushed from the body.
Lyme Disease Blood Tests After Treatment
Following treatment for Lyme disease, and co-infections in some cases, patients will likely undergo another blood test to assess the presence of antibodies to Borrelia. At this point a low level of IgM antibodies suggests that the disease has been successfully treated and the body has slowed production of antibodies now it no longer needs to try to fight the invading organism. However, low antibody levels (titers) may also be present where the organism is still present but has bound to the antibodies, thus evading detection. This is one of the criticism against such Lyme disease blood tests as only unbound antibodies are detectable by ELISA and Western Blot, thus complicating assumptions regarding the implications of high or low levels and the actual presence of bacteria at the time of the Lyme disease blood test.