Health officials in Grand Rapids, Minnesota have found that municipal water supply likely sparked an outbreak of Legionnaires’ disease.

There are typically dozens of separate outbreaks per year, with the largest portion of cases historically being linked to healthcare facilities, according to the Centers for Disease Control and Prevention. About 1 in 10 people infected die of the disease.

Since April 2023, 14 cases of the lung disease have been confirmed, according to a press release from the state's health department. The disease is caused by inhaling Legionella bacteria found in water, the release says.

“We are taking this situation very seriously,” said Jessica Hancock-Allen, director of the Minnesota Department of Health, MDH, Infectious Disease Epidemiology, Prevention and Control Division, in a statement. “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."

Hancock-Allen notes that most cases can be treated successfully with antibiotics, but an early diagnosis and the right treatment is important for recovery.

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According to the release, a common factor in each case was exposure to the municipal water supply. They then tested the water of two buildings in the community and both tested positive for the bacteria.

Officials found that not only were the bacteria in the buildings related to one another, they were also related to bacteria found in patients' respiratory samples.

“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.”

Julie Kennedy, the city's public utilities general manager said they will focus on developing a plan to flush out and and disinfect areas of the water system to reduce the risk of Legionella.

Kennedy says the city is looking into installing a chlorination system, but the process could be complicated.

"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,” says Kennedy in a statement.

As the plan continues to develop, Kennedy says the city will send out local updates and customer notices while they continue to work with MDH and other experts to assess the water distribution system to "to determine the best long-term solution.”

Do people in Grand Rapids need to boil their water?

Kennedy told USA TODAY in an email that the public water is safe to drink and that the city is not under any kind of boil water notice.

"The water tests conducted by MDH at our water treatment plant, water towers, and service center showed no presence of Legionella bacteria," said Kennedy.

While the water is safe to drink, showers may require some extra precautions.

"If the steam or mist from a shower is inhaled and the water in the plumbing contained Legionella then yes, there is potential for infection," said Kennedy.

She recommends people maintain waters outside of the ideal range for Legionella growth, which is 70 to 113 degrees Fahrenheit according to the CDC.

Kennedy says that "regularly flushing faucets and showerheads, especially if they have not been used recently," is another way to control the spread of the infection.

What is Legionnaires’ disease?

Legionnaires’ disease is a serious type of pneumonia, according to the CDC. The disease is a lung infection, which is also known as Pontiac fever, is caused by Legionella bacteria that are found naturally in freshwater, like lakes and streams.

The bacteria can cause health problems when they grow and spread in building water systems, including air conditioning systems. The disease can spread person-to-person, however, more frequently it spreads when someone inhales particles that grew in an indoor setting. Roughly one-third of the outbreaks occur in health care facilities, where patients may be especially vulnerable – a possible explanation for why 10% of people infected die of the disease.

"People can get sick when they breathe in small droplets of water or accidentally swallow water containing Legionella into the lungs," according to the CDC.

The disease itself isn't usually contagious, but it can spread it from person to person under very rare circumstances.

How to control the spread of Legionnaires’ disease

The CDC says there are ways to control the spread of the bacteria through building and maintaining a water management program.

It states people can also do the following:

• Keep water temperatures outside the ideal range for Legionella growth. But be aware that the bacteria can grow in temperatures as low as 68 degrees.
• Prevent water stagnation.
• Maintain devices to prevent sediment, scale, corrosion, and biofilm since they provide a habitat and nutrients for Legionella.

Legionnaires’ disease symptoms

The infection is similar to other types of pneumonia. The CDC states patients exposed to the bacteria may experience the following:

• Cough
• Shortness of breath
• Fever
• Muscle aches
• Headaches

Is Legionnaires’ disease common?

There aren't many cases reported each year, the CDC says that the number of cases is on the rise. It also believes that cases may be around two to three times higher than what is reported.

"Health departments reported nearly 10,000 cases of Legionnaires’ disease in the United States in 2018," states the CDC. "However, because Legionnaires’ disease is likely underdiagnosed, this number may underestimate the true incidence."