What follow-up test is recommended after equivocal Lyme antibody results?

When evaluating equivocal Lyme antibody results, the recommended follow-up test is the Western blot. This test is a more specific method for confirming the presence of antibodies against Lyme disease, particularly when initial tests yield inconclusive results.

The Western blot detects specific antibodies to the Borrelia burgdorferi bacteria, the causative agent of Lyme disease, providing a clearer indication of infection. It distinguishes between false positives and true positives, which can be critical in the clinical decision-making process.

In contrast, repeating the ELISA would not provide additional information, as it's the same test that produced the equivocal result initially. Rapid antigen testing is not typically used for Lyme disease diagnosis, as it lacks the specificity needed to confirm the disease. DNA PCR, while useful in certain scenarios, particularly in early disease or when disseminated Lyme disease is suspected, is not the first-line test for follow-up after equivocal antibody tests. Thus, the Western blot stands out as the most appropriate next step in managing equivocal Lyme antibody results.