The Milwaukee Health Department reported 58 clinically confirmed Legionnaires’ disease cases in Milwaukee County from June 1 to Sept. 30, 2013. This is surprising since it is more than double the typical number of annual cases for the last five years.
78% of the cases from June through September occurred in the city of Milwaukee, and 57 of 58 cases were hospitalized for their illness.
The Milwaukee Health Department performed an environmental investigation and sampled 11 sites throughout the city. They took water samples and dozens of swabs. The results showed that three cooling towers were positive for Legionella pneumophila one of the bacteria that can cause Legionnaires’ disease.
31 of the 58 patients (53%) lived within three miles of one of the Legionella-positive cooling towers, but this finding was not significant, so an association between patient location and infected cooling tower could not be confirmed in the investigation.
After meeting with the cooling tower contractors, the health department found that there was a gap in tower maintenance due to weather.
“The investigation underscores the need for local public health authorities to be prepared to rapidly enhance surveillance, deliver appropriate public risk messaging and coordinate with the private sector to mitigate environmental transmission of Legionella within a community,” said the Milwaukee Health Department.
To read the full report about the Milwaukee Legionnaires’ disease outbreak, please see the Morbidity and Mortality Weekly Report on the CDC website at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6303a4.htm?s_cid=mm6303a4_w