Erythema Chronicum Migrans and Lyme Arthritis

To the Editor.— The discussion in MEDICAL NEWS (236:241, 1976) of a new form of arthritis in New England prompts us to submit a follow-up on our original report "Erythema Chronicum Migrans [ECM] in the United States" (236:859, 1976). We have this summer seen six more cases of ECM, for a total of ten cases. All erythemas responded dramatically to treatment with penicillin or erythromycin, with resolution within 24 to 48 hours of beginning treatment. In two of these patients (20% of our series), a monoarticular arthritis with effusion subsequently developed. Both patients had serum positive for rheumatoid factor. One patient was systemically ill, with fever, myalgia, and malaise. He experienced complete relief of symptoms and resolution of the effusion within 48 hours of beginning the penicillin regimen. The other patient with arthritis was less symptomatic, and symptoms and effusion gradually resolved over three weeks under expectant observation. On exchange