Notes from the field: Increase in reported legionellosis - Milwaukee, Wisconsin, June-September 2013.

In early July 2013, the City of Milwaukee Health Department (MHD) was notified by the Wisconsin Division of Public Health of an increase in reported cases of legionellosis in southeastern Wisconsin. Legionellosis is a reportable disease to state and local public health authorities in Wisconsin. During June 1-September 30, 2013, a total of 58 clinically diagnosed cases of Legionnaires' disease, confirmed by laboratory testing, were reported in Milwaukee County, more than twice the number of total annual case reports in each of the previous 5 years. Forty-five (78%) of these cases were reported in the city of Milwaukee. The median age of county patients was 53 years (range = 29-77 years); all but one was hospitalized, and no deaths were reported. MHD received one report of a death attributed to legionellosis in the county during this period.