Borrelia arthritis in Sweden.

Antibodies to Borrelia spirochetes were determined by an enzyme-linked immunosorbent assay (ELISA) in sera from 298 patients with postinfectious arthritis. Sera from healthy individuals, patients with acute infectious meningitis of proven etiology and patients with multiple sclerosis served as controls. Titers above the 100% percentile of controls were found in five of 298 (2%) arthritis patients. Two of the arthritis patients had higher titers than any titers previously found in Swedish patients with Borrelia meningitis. It is concluded that a Borrelia etiology should be considered in patients with reactive or postinfectious arthritis of unknown origin.