The Western immunoblot test is the most widely used test for diagnosing Lyme disease. Recently, the US Centers for Disease Control (CDC) revised their criteria for the test. These new criteria fail to include the most significant antigens and so may fail to make the diagnosis even when disease is present.
In addition, other factors can interfere with the diagnosis when testing blood, including:
Recent infection before an immune response
The causal spirochaete bacteria may be encapsulated by host tissue
There may be no spirochaetes in the body fluid on the day of the test
The test only looks for one strain of B. burg dorferi, yet there are over 300 strains
Recent antibiotic or anti inflammatory treatment
Babesiosis co-infection (another tick borne disease) may cause immunosuppression
There may be other causes of immunosup pression (e.g. immunosuppressive drugs)
The lab test is not standardised to detect late stage disease
The lab may have a poor technical capability for detecting Lyme disease.