Lyme disease is a "'clinical" diagnosis determined by your physician/HCP and relying on their experience in diagnosing tick-borne diseases. Testing is an adjunct to their clinical diagnosis. A negative test CANNOT rule out Lyme disease. Many physicians use a checklist of Lyme symptoms, employing clinical assessment and testing to rule out other diseases. Lyme disease is considered a disease of "exclusion" which means that other diseases with overlapping signs and symptoms must be considered and eliminated (differential diagnosis) before determining the Lyme diagnosis.