Both epidemiologic and laboratory data point to areas of the municipal water system as the source of the Legionnaires’ disease outbreak in the northeastern Minnesota city of Grand Rapids, according to the Minnesota Department of Health (MDH).
Fourteen cases of Legionnaires’ disease have been confirmed since April 2023. Legionnaires’ disease is a serious type of pneumonia (lung infection) caused by inhaling Legionella bacteria found in water. Likely case exposures have been geographically clustered in homes and other buildings in the area north of Golf Course Road/SE 10th Street, south of NE/NW 8th Street, east of 11th Avenue SW/10th Avenue NW, and west of 7th Avenue SE/8th Avenue NE.
“We are taking this situation very seriously,” said Jessica Hancock-Allen, director of the MDH 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.”
Since the first cases of Legionnaires’ disease were reported, MDH has been investigating the source of the outbreak. MDH determined the municipal water supply was the only common exposure reported by the people who got sick. Water samples from two buildings in the community subsequently tested positive for Legionella and the Legionella bacteria from the two buildings were highly related to each other and to the Legionella bacteria from patient respiratory samples. This provided additional evidence pointing to the municipal water supply as the source.
“We are working in partnership with the local water utility to determine the best way to address the situation,” said Tom Hogan, director of MDH’s Environmental Health Division. “Additional water sampling is planned, and the results will be analyzed and used to inform additional actions and communication.”
Legionella is commonly found in natural and manmade aquatic environments and can be found at low concentrations in any public water system. Legionella can live and grow in pipes and devices that use water. It lives and grows particularly well in water that is stagnant (not flowing), between 70°F and 120°F, or when it is not treated with adequate water treatment chemicals, such as chlorine. The Grand Rapids Public Utilities water supply is 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.
“Our immediate focus is developing the provisional plan to flush and disinfect areas of our water system, aiming to reduce the risk of Legionella. Installing a chlorination system is being looked into, but 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,” said Julie Kennedy, Grand Rapids Public Utilities general manager. “We will be providing local updates and customer notices as that plan develops along with continuing to work with MDH and a team of experts to conduct a thorough assessment of our water distribution system to determine the best long-term solution.”
People can get Legionnaires’ disease after breathing in water droplets containing Legionella bacteria. Common sources of exposure include devices that create water mist, such as hot tubs, showers, decorative fountains and cooling towers. In this outbreak, it appears the most likely source of exposure was water mist from fixtures in buildings such as showers or faucets.
Legionnaires’ disease is not spread from person to person. People do not get infected from drinking (swallowing) water. Rarely, people with swallowing difficulties could be infected if water “goes down the wrong pipe” while drinking and gets into the lungs. Symptoms of Legionnaires’ disease include fever, chills, cough, shortness of breath, headaches, muscle aches and fatigue. Other symptoms may include weakness, loss of appetite, confusion, diarrhea and nausea.
Legionnaires’ disease can be serious and sometimes fatal. In general, about one out of every 10 people who get sick with Legionnaires’ disease dies. Of the 14 cases associated with the Grand Rapids outbreak, all have been adults and 11 have required hospitalization for their illness. To date, no deaths have occurred associated with this outbreak.
In 2023, Minnesota had 134 cases, including six deaths, related to Legionnaires’ disease.
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 or medications that affect the immune system.
MDH has asked health care providers to watch for any additional patients with symptoms that might indicate Legionnaires’ disease. MDH is not recommending testing for people who may have been exposed but do not have symptoms.
Building owners should follow best practices for maintaining a healthy building water system and are encouraged to develop and implement a water management program. Best practices for Legionella water management programs require a detectable level of disinfectant (such as chlorine) throughout a building water system.
More information is available in the Centers for Disease Control and Prevention (CDC) Toolkit: Developing a Water Management Program to Reduce Legionella Growth and Spread in Buildings.
Residents can take the following actions at home to help reduce the risk of waterborne diseases, including Legionella infection:
• Regularly clean all devices that use water to remove dirt, debris, germs and other impurities.
• Always follow the manufacturer’s recommendations regarding using, cleaning and maintaining your water-related devices.
• Maintain in-home medical equipment. If using medical equipment that requires water for use, such as CPAP or BiPAP machines or Neti Pots, only distilled water should be used. Devices should be cleaned regularly, per manufacturer’s recommendations.
• Follow the manufacturer’s instructions for cleaning and drying your portable humidifier. Use distilled or boiled (and then cooled) water or water disinfected with chlorine bleach in portable humidifiers.
• Clean showerheads and faucet aerators whenever you can see buildup to help prevent germs from growing within the faucet. You may need to remove the showerheads and hose and soak them in a solution (such as white vinegar) to remove buildup. Follow the manufacturer’s instructions for cleaning.
• Keep your water heater set to a minimum of 120°F. A water temperature of 130°F to 140°F can kill many harmful germs, but also increases the risk of scalding. If you set the temperature above 120°F, take extra precautions to mix cold and hot water (using thermostatic valves) at the faucet or shower to avoid scalding. This is especially important if young children, older adults, or other people at increased risk of scalding live in your home.
More information on preventing waterborne germs at home can be found on the CDC's website.
Updates from the city can be found on the Grand Rapids Public Utility’s Legionella Mitigation, Updates, and Information website. More information about Legionnaire’s disease can be found on MDH’s Legionellosis (Legionella) website and on CDC’s Legionella website.