Participants whose test results are positive for Borrelia burgdorferi will be followed at NIH at intervals of 3 to 6 months until it is determined whether there is infection. Those who are infected will be offered treatment with the antibiotic ceftriaxone. Following treatment, patients will return to the NIH Clinical Center for follow-up visits 1 week after treatment and again at 3, 6 and 12 months. The lumbar puncture, hearing examination, blood and urine tests will be repeated at these visits to evaluate the response to treatment, and the leukapheresis will be repeated for research purposes. Patients whose MRI was abnormal during therapy will have a repeat MRI at the 3-month, 6-month and 1-year visits.