HOPKINS, Minn. — A cooling tower at a manufacturing company is the likely source an outbreak of Legionnaires’ disease in Hopkins that sickened 23 people and caused one death last month, the Minnesota Department of Health said Wednesday.
Laboratory tests show the strain of Legionella bacteria found in one of the two cooling towers at Citrus Systems Inc. matched the strain in samples taken from patients linked to the outbreak, the department said in a statement. Other cooling towers in the outbreak area tested negative for the strain.
Deputy State Epidemiologist Richard Danila said he had “great confidence” that the mystery has been solved.
The company, which manufactures beverage and juice products, has cooperated fully, the department said. Samples were taken from the towers on Sept. 27 and they were cleaned and disinfected the same day. The company’s food products were not affected by the outbreak nor were they responsible for it, the department said.
Legionnaires’ disease is a respiratory infection people can get from inhaling contaminated mist from sources such as cooling towers for large buildings. Seventeen people were hospitalized during the outbreak, but no new cases have been reported since Sept. 22. The only common thread among the victims was that they lived, worked or spent time in the area.
While the typical 10-day incubation period has passed, Danila said it’s still possible another case could turn up if someone was exposed Sept. 27.
“We don’t know in this case exactly what went wrong to cause the build-up of Legionella,” Danila said. “This situation clearly demonstrates how difficult it can be to keep systems free of Legionella, even when they are well-maintained.”
The company said in a statement that it is working with the department to ensure that there’s no new exposure risk and that it has a “robust” water management plan in place.