All participants undergo a clinical examination, blood tests, between two to four skin biopsies (removal of a small piece of tissue for laboratory examination), and complete two health questionnaires. The biopsies are taken from the erythema migrans lesion in patients with Lyme disease and from skin on the legs, forearms, buttocks, or side from healthy volunteers. To collect the tissue, the skin at the biopsy site is numbed with injection of a local anesthetic and a sharp instrument is then used to remove a round plug of skin about the size of a pencil eraser. The wound may be closed with one or two sutures, or allowed to heal without sutures. The sutures are removed after a week to 10 days.