Dr. Gerard Sheehan:

In general, if somebody has erythema migrans, the rash, whether antibody positive or antibody negative, and takes the correct course of antibiotics, it will be said the bug is gone and he or she has been cured. If somebody presents two years later with a facial palsy, for example, arthritis or a heart block, clearly one will re-examine the possibility that one was wrong. One will examine the possibility that there has been a second infection along the way. In general, the starting point is that the facial palsy, arthritis or heart block might have another cause. One should be open to a variety of possibilities, including that somehow the antibiotics failed. One will, of course, err on the side of giving treatment directed at that complication of Lyme disease if the possibility is countenanced.