Initial Presentation and Time to Treatment in Early Lyme Disease.

The erythema migrans (EM) rash is an important initial diagnostic sign of early Lyme disease. We tested the hypothesis that patients who noticed EM first differed from those who noticed viral-like symptoms first. "EM First" participants (167/271, 61.6%) had shorter illness duration before treatment (5.0 versus 6.2 days, P = 0.019), were more likely to have seen or removed a tick (P = 0.048) and to be non-Hispanic White (P = 0.025), and were less likely to present with disseminated lesions at the time of diagnosis (P = 0.003) than "Symptoms First" participants (104/271, 38.4%). In multivariate analyses, EM First participants had a 22% decrease in time to treatment (P = 0.012) compared with Symptoms First participants, suggesting that initial presentation affects time to treatment. In a large minority of patients, EM may not be the initial sign or symptom of early Lyme disease. There is a need for rapid diagnostics and improved physician awareness of the varied manifestations of early Lyme disease.