How should I interpret serological test results for Lyme disease, and when should I consider referral to a specialist?

Serological test results for Lyme disease should be interpreted as follows: a positive or equivocal ELISA test should be followed by an immunoblot test for confirmation, and treatment may be started while awaiting results if there is high clinical suspicion ¹.

If the ELISA is negative but symptoms persist, review the patient's history and consider alternative diagnoses; if Lyme disease is still suspected within 4 weeks of symptom onset, repeat the ELISA after 4–6 weeks, or perform an immunoblot test if symptoms have lasted 12 weeks or more ¹.

A positive immunoblot test confirms Lyme disease, and treatment with antibiotics should be initiated ¹.

If the immunoblot is negative, regardless of ELISA results, but symptoms persist, consider referral to a specialist for further assessment, additional testing (such as synovial fluid analysis or lumbar puncture), or to explore alternative diagnoses ¹.

If the immunoblot is negative and symptoms have resolved, no treatment is required ¹.

Referral to a specialist should also be considered in cases with focal symptoms or neurological, cardiac, or dermatological features, or if there is diagnostic uncertainty ¹.