Dale Adams just thought he had a cold when he felt tired and run-down last November.

“Northerners! We try and tough through everything,” he said. 

But after eight or nine days, the Grand Rapids city council member wasn’t getting any better. His son urged him to seek medical treatment.

Doctors diagnosed Adams with Legionnaires’ disease, a serious form of pneumonia. He spent several days in the hospital for treatment.

“It knocked me for a loop,” said Adams, 73, who also serves on the city’s public utilities commission. “I felt like I’d been drug through a wringer.”

Adams has since recovered. He was lucky. Legionnaires’ disease can be deadly, especially in people over 50 and those with certain health conditions, such as chronic lung disease, diabetes or weak immune systems.

Last April, state health officials began investigating Legionnaires’ in Grand Rapids, a city with 11,000 residents in northeastern Minnesota. By July, they’d confirmed five cases, the same number as in the previous 10 years.

The outbreak has now sickened 15 people, including 11 who were hospitalized. No one has died.

Health officials noticed the cases were clustered in one area of the city. Water samples from the city’s treatment plant were negative. But two community buildings connected to the city water supply tested positive for Legionella, the bacteria that causes Legionnaires’ disease.

Using genome sequencing, investigators linked that bacteria to patients’ respiratory samples. They determined the people who got sick had only one thing in common: They were all exposed to the city’s water. 

“In the distribution system that’s bringing the water into the homes or businesses in this area where people are being exposed, something is happening there,” said Trisha Robinson, who supervises the waterborne diseases unit at the Minnesota Department of Health.

People develop Legionnaires’ disease by breathing in water droplets containing Legionella bacteria. Often, that’s through devices that create mist or vapor, such as showers, hot tubs, decorative fountains or cooling towers.

Many people who are exposed to the bacteria don’t get sick. People cannot get Legionnaires’ from drinking water that contains Legionella, unless they accidentally inhale water into the airway. The disease is not spread from person to person. 

Legionella can be found in low concentrations in any public water system. It thrives in stagnant water, especially water that hasn’t been disinfected with chlorine, said Julie Kennedy, general manager of the city’s public utilities.

“That’s when it begins to pose that health risk, if somebody inhales or breathes in those small droplets of water that have been contaminated with a higher level of Legionella concentration,” Kennedy said.

Grand Rapids is one of 64 municipal water systems in Minnesota that don’t regularly chlorinate, according to the state health department. The vast majority are cities with fewer than 1,000 people. 

“Unfortunately, every time one of these outbreaks like this occurs, it just reminds us of why chlorination is so important,” said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “It really is the stopgap between a city system becoming contaminated and staying contaminated.”

Brainerd previously was the largest Minnesota city that didn’t regularly disinfect its water supply. However, it has been chlorinating since coliform bacteria was detected last year.

Legionnaires’ cases nationwide are on the rise, due in part to better methods of diagnosis, Osterholm said. However, health experts believe many cases go unreported. 

Minnesota had 134 cases of Legionnaires’ last year, including six deaths. That’s up from 109 reported cases in 2022. Most cases are sporadic and not associated with an outbreak.

For Grand Rapids residents, the outbreak has been unsettling. 

Deb Larson manages the city’s two Subway restaurants, and lives in an area with a cluster of cases. She attended a recent community meeting hoping to get more answers.

“I have neighbors that are both retired and are older, and have heart problems,” Larson said. “I’m just worried for them too. Is it safe to take hot showers? Do we have the bacteria in our homes? Are our homes going to be tested?”

During the meeting, health officials said they are continuing to investigate the source of the bacteria. They’ve expanded testing and are working on a plan to flush and disinfect areas of the city’s water system. They stress that the city’s water remains safe to drink.

Whether Grand Rapids continues to chlorinate its water long term remains an open question. Adams says he’s heard from many people who say they like their water as it is.

“I do too,” he said. “But if we find out that this is a way that could eliminate or severely reduce the opportunities for (getting ill) to happen to other people out there, I’m going to support it.”

Some residents at Friday’s meeting voiced concerns about health effects of chlorination. It can interact with organic matter in the water to create byproducts that can be carcinogenic.

Chad Seidel is president of Corona Environmental, a consulting firm Grand Rapids hired to help with the Legionella issue. He said there’s a “balancing act” between minimizing the acute risks of bacterial infection and other microbes with long-term risks from disinfection byproducts.

“Our deliberative approach will absolutely be assessing those things, and acknowledging the fact that there are some trade-offs made in that, but to the betterment of the overall public health for the community,” Seidel said.

If it does chlorinate, the city would monitor the water for byproducts, he said.

In the meantime, Seidel said people can take steps at home to reduce their risk of contracting Legionnaires’ disease. 

Those include cleaning faucets and showerheads, using distilled water in devices such as humidifiers and CPAP machines and turning up their water heater to at least 120 degrees.

Health officials advise anyone with symptoms of Legionnaires’, including fever, cough, shortness of breath and headache, to contact their doctor.