Source:http://linkedlifedata.com/resource/umls/id/C0242381
AIR: WHAT: Lyme arthritis. Lyme Arthritis: a viral arthritis characterized by a preceding characteristic rash, erythema chronicum migrans, and typically brief recurrent episodes of asymmetric, pauciarticular swelling and pain primarily involving the larger joints, particularly the knee. The disease is named because of a close geographic clustering of cases seen in Lyme, Connecticut in 1975. WHY: Lyme arthritis can sometimes be confused with rheumatic fever or with pauciarticular juvenile rheumatoid arthritis, and thus must be excluded when diagnosing the two latter diseases. HOW: Lyme arthritis is typically brief (one week) but recurrent. The large joints are usually involved, particularly the knee. When the knee is involved it is usually more swollen than painful. As noted, the distribution of the arthritis tends to be asymmetrical. A rash (erythema chronicum migrans) precedes the development of arthritis, in contrast to the rash (erythema marginatum) seen in rheumatic fever, which accompanies the arthritis