September 30, 2016
Hopkins Legionnaires’ investigation
The Minnesota Department of Health (MDH) continues to investigate an outbreak of Legionnaire’s disease in Hopkins. To date, 23 cases of Legionnaires’ disease have been confirmed in people who live, work or spent time in Hopkins. This total reflects three additional cases confirmed by MDH between Sept. 28 and Sept. 30.
The most recent illness onset date for known cases is Sept. 22.
The pattern of where cases were likely exposed is consistent with a community-wide exposure to contaminated water that became aerosolized, most likely from a cooling tower. Extensive interviews with Legionnaires’ cases and/or family members did not identify a common exposure – such as a restaurant or a store or specific building -- other than living, working, or spending time in Hopkins.
To date, seven locations with one or more cooling towers have been identified by Hennepin County Public Health and the City of Hopkins, in collaboration with MDH, as being possible sources. As of Sept. 29, all of these cooling towers have been or are being remediated by their owners.
Environmental samples from cooling towers within the area of concern have been collected. These tests are in process. Legionella is a slow-growing bacteria and testing for the bacteria in the laboratory can take weeks.
While the remediation of known cooling towers is important in reducing any ongoing risk to people in the area, MDH will not consider the investigation complete until all nearby cooling towers that could be a source of the Hopkins illnesses are identified and remediated, and no additional cases are identified.
It’s important to note that cooling towers are not regulated in Minnesota and therefore no state or local registry or master list of cooling towers exists, making identification difficult. Building owners are responsible for operating cooling towers consistent with industry standards. MDH recommends all building owners with cooling towers review guidelines from the Centers for Disease Control and Prevention regarding implementation of a water management program to reduce Legionella growth. A toolkit and more information can be found at: CDC: Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings.
Minnesota and many other states have seen an increase in the number of Legionnaires’ disease cases in recent years. From 2012 through 2015, Minnesota had an annual total of 50-58 confirmed cases of Legionnaires’ disease. To date in 2016, more than 90 cases have been reported. Most cases of Legionnaires’ are reported in later summer and early fall.
Cases of Legionnaires’ disease not associated with the Hopkins outbreak continue to be reported to MDH. All cases are interviewed to identify potential clusters or outbreaks; most cases are not a part of an outbreak or cluster.
Most people exposed to Legionella don’t become infected. People who may be at an increased risk include those over the age of 50, smokers, or those with certain medical conditions, including weakened immune systems, chronic lung disease or other chronic health conditions.
The best advice for concerned Minnesotans is to be aware of the symptoms of potential infection with Legionella and seek medical care promptly if you or a loved one develops these symptoms.
Symptoms of Legionella infection can include fever, chills, headaches, muscle aches, fatigue, shortness of breath, cough, mental confusion, diarrhea, and vomiting. Legionella infection can be diagnosed by health care providers through non-invasive means using a urine test and can be treated with antibiotics.
More information on Legionnaires’ disease can be found on the MDH website at About Legionellosis (Legionella).