With warmer weather come the annual warnings about tick-borne infections and, in particular, about Lyme disease. There has been considerable publicity about substantial increases in the incidence of Lyme disease; however, even though the incidence of Lyme disease has increased from 2007 to 2016, there has not been a statistically significant increase in the number of reported cases of Lyme disease in the United States during the most recent 4 years (2013)(2014)(2015)(2016) for which data are available. 1 In 2016, a total of 26 203 confirmed cases of Lyme disease were reported in the United States (incidence = 8.1 cases/100 000 population), 1 although an estimate suggests that approximately 300 000 cases occur annually. 2 The geographic distribution of Lyme disease (although still limited primarily to New England, the Middle Atlantic states, and Wisconsin and neighboring states) has increased, with evidence of spread to new areas, generally in locations that are adjacent to recognized endemic areas.Lyme disease is caused by infection with Lyme Borrelia, which include Borrelia burgdorferi, Borrelia garinii, and others, and are transmitted to humans through the bite of infected Ixodes ticks; in the United States, primarily by Ixodes scapularis-the deer tick. The vast majority of patients with Lyme disease (Ն90%) develop the characteristic skin lesion, erythema migrans. Extracutaneous manifestations may include facial nerve palsy, lymphocytic meningitis, radiculopathy, heart block from myopericarditis, and pauciarticular large joint arthritis.