Objective.- To describe outcomes of treated Lyme arthritis in an endemic area of western Switzerland, where some of the first cases of Lyme disease outside the United States were reported.

Patients and methods.- We retrospectively studied 24 patients (15 males and nine females, mean age 38.7 years) managed by rheumatologists between 1994 and 1999 for Borrelia burgdorferi arthritis manifesting as monoarthritis (n = 20), oligoarthritis (n = 3), or polyarthritis (n = 1). The knee was affected in 20 (85%) patients. Nine patients reported a history of tick bite and four of erythema chronicum migrans. All the patients but one had a high titer of antibodies to B. burgdorferi by ELISA and all but two had a positive immunoblot test (22 positive for all three types of B. burgdorferi found in Switzerland and one positive only for B. burgdorferi sensu stricto). Joint fluid PCR for B. burgdorferi was done in nine patients and was positive in six.

Results.- All 24 patients received antibiotic therapy, orally (n = 10) or parenterally (n = 14). A second course of antibiotic therapy was used in four patients with persistent arthritis. A rapid response was noted in 13 patients. Intraarticular glucocorticoid therapy or a synoviorthesis was required in nine patients. After a mean follow-up of 40 months (range, 6-84 months), none of the patients had chronic arthritis but two reported persistent muscle or joint pain.

Conclusion.- Recurrent or chronic arthritis, which has been reported in treated patients in the United States, did not occur in our series. This may be ascribable to differences in B. burgdorferi subtypes, as in the United States only B. burgdorferi sensu stricto is found.