State health officials Monday said they’ve identified the source of a Legionnaires’ disease outbreak in northern Minnesota.

The Minnesota Department of Health said testing points to parts of the city water system in Grand Rapids as the source. Fourteen cases of the disease have been identified in the area since last April; 11 of those people were hospitalized. No one has died.

“We are taking this situation very seriously,” said Jessica Hancock-Allen, director of the health department’s Infectious Disease Epidemiology, Prevention and Control Division. “While most people exposed to Legionella bacteria do not develop Legionnaires’ disease, the best thing to do if you experience symptoms of pneumonia — such as cough, shortness of breath, fever and headache — is contact your health care provider right away. Most cases can be successfully treated with antibiotics, but prompt diagnosis and appropriate antibiotic treatment is important.” 

Grand Rapids Public Utilities said it’s working on a plan to flush and disinfect the water system.

“We are working in partnership with the local water utility to determine the best way to address the situation,” said Tom Hogan, director of the health department’s Environmental Health Division. “Additional water sampling is planned, and the results will be analyzed and used to inform additional actions and communication.”

The state health department said Grand Rapids has “one of the few community water systems in Minnesota that does not chlorinate its water. This is because some systems that draw water from groundwater sources, such as community wells, are not required to add disinfectants.”

Julie Kennedy, general manager of Grand Rapids Public Utilities, said the utility is considering adding chlorination — but it’s not something that can be done quickly.

“Introducing chlorination to a previously unchlorinated system is a complex process, so our approach needs to be methodical to ensure we avoid any additional health, safety or distribution system complications,” she said in a state health department news release.

Kennedy said the utility will give customers updates as plans develop.

Legionnaires’ is a form of pneumonia caused by exposure to Legionella bacteria. Health officials say it’s spread by breathing in water mist, such as from a shower. People do not get infected by drinking water, officials said, and the disease is not spread from person to person.

In 2023, Minnesota had 134 cases, including six deaths, related to Legionnaires’ disease.

Most people exposed to Legionella bacteria do not develop Legionnaires’ disease, according to the state health department. People at increased risk of infection and severe illness include those ages 50 years and older and current or former smokers. Other risk factors include chronic health conditions such as lung, kidney, or liver disease; diabetes; cancer; and conditions and medications that affect the immune system.

The health department outlined several steps that residents can take to reduce the risk of waterborne diseases.

• Regularly clean any devices that use water, to remove dirt, debris, germs and other impurities. These can include medical equipment, humidifiers, shower heads and faucet aerators.

• If using medical equipment that requires water, such as CPAP or BiPAP machines or Neti Pots, use only distilled water.

• For portable humidifiers, use distilled water; water that’s been boiled and then cooled; or water disinfected with chlorine bleach.

• Keep water heaters set to a minimum of 120 degrees. The health department noted that a water heater temperature of 130 to 140 degrees can kill many harmful germs, but also increases the risk of scalding — and advised taking extra precautions.