Multiple sclerosis controls: For the purposes of this study, a multiple sclerosis control is defined as an otherwise healthy male or female aged 18 and above with relapsing-remitting or progressive multiple sclerosis as defined by the Clinical Trial Committee of the National Multiple Sclerosis Society and no evidence of prior exposure to B.burgdorferi as indicate by negative history for Lyme disease and negative Western blot for B.burgdorferi in the serum by the CDC criteria. Patients should have a Kurtzke or Expanded Disability Status Scale (EDSS) between 1 to 5.