A cooling tower that eluded investigators’ initial sweep in Hopkins has been identified as the source of a Legionnaires’ disease outbreak that sickened 23 people and contributed to one death.
The Minnesota Department of Health reported Wednesday that the three-year-old cooling tower at the Citrus Systems juice manufacturing plant near downtown Hopkins was the culprit, and that testing found an exact genetic match between Legionella bacterial samples from the tower and from four of the sickened patients.
The tower was sanitized on Sept. 27, and no new infections have been reported since Sept. 23, meaning “the outbreak for all intents and purposes is over,” said Richard Danila, deputy state epidemiologist.
When a cluster of Legionnaires’ cases emerged in early September, state and local health authorities began searching for industrial cooling towers using online, overhead maps of the area.
Towers often are the culprits in such outbreaks, because people are only infected when they inhale aerosolized water particles containing Legionella bacteria.
Trouble is, the cooling towers at Citrus Systems sit next to the building on 11th Avenue, just south of Excelsior Boulevard, and weren’t identified until the Health Department received a tip from the public on Sept. 26.
There is no state or public health registry of cooling towers. Health authorities had checked 14 other cooling towers in the Hopkins area that they could identify from mapping and other sources. Testing found Legionella in other towers, but not the exact strain involved in the outbreak.
The tip quickly made sense. Many of the infected people lived and worked in nearby buildings, while others walked or shopped nearby. One person lived outside Hopkins but drove near the building to pick up a client for work.
“It was right in the heart of where our cases lived and worked,” Danila said, “or we could put them in that area because they shopped or exercised in that area.”
Seventeen of the 23 infected people in the outbreak were hospitalized.
Citrus Systems makes various juices, smoothies and teas; Danila stressed that consumers have no risk of contracting the disease by drinking these beverages.
“Even if you were drinking water that had Legionalla in it, you wouldn’t get sick,” he said.
The source is somewhat surprising because the company has newer cooling towers and a reputable contractor to maintain them. The towers also have buffers that are supposed to limit the spread of aerosolized mist.
“We don’t know exactly why Legionella was able to grow in this cooling tower yet,” Danila said.
State health authorities will work with the company’s contractor, which will be conducting heightened testing over the next year.
A statement from company spokesman Terry Richards said Citrus Systems is “fully cooperating with the ... investigation to ensure that there is no further exposure risk moving forward.”
This is just the second time that whole-genome sequencing has identified the source of a Legionnaires’ outbreak. The first was last year in the Bronx borough of New York City, where a cooling tower from a two-year-old hotel was identified as the source.
A testing lab in New York and the U.S. Centers for Disease Control and Prevention assisted Minnesota authorities in analyzing and comparing the DNA fingerprints of the bacteria samples.
For Mary Myers, a Hopkins resident and an early victim of the outbreak, Wednesday’s news was a huge relief.
“It is pretty scary,” she said. “Simply walking around knowing you can catch something that could be potentially deadly is frightening.”
Myers became ill in early September, with allergy symptoms and then a “killer headache,” but she didn’t realize it might be Legionnaires’ disease until her husband texted her after seeing a Health Department announcement.
Myers, 55, quickly read a description of Legionnaires’ symptoms and then headed to urgent care. “I looked at what the Health Department was saying, the symptoms and progression was spot on with what I had,” she said. “The doctor was really quite surprised.”
She would have to wait five days before test results came back. By the time the diagnosis was made, she had developed pneumonia. “I didn’t eat for like five days, just had absolutely no desire,” Myers said.
About a week later, she got a telephone call from a state health investigator. “They wanted to know every place I had been in the previous two weeks,” Myers said.
Today she feels “just fine,” and is relieved no one else is likely to catch the disease. “I don’t think I’ve ever been so sick in my life.”
Staff writer Glenn Howatt contributed to this report.