In 1982, the U.S. Centers for Disease Control and Prevention (CDC) launched a national surveillance for tick-borne Lyme disease (LD) with 11 states reporting 491 cases of infection. Lyme disease is defined as the presence of an erythema migrans rash or at least one objective sign of musculoskeletal, neurologic, or cardiovascular disease and laboratory confirmation of infection.

In 1993, 8,185 cases of LD were reported to the CDC by 44 state health departments, 1492 (15%) fewer cases than were reported in 1992 (9,677). Most cases were reported from the northeastern, mid-Atlantic, north-central, and Pacific coastal regions.