Five people who live or work in Hopkins, Minnesota, have been diagnosed with Legionnaire’ disease, a severe form of pneumonia caused by breathing in water mist containing Legionella bacteria, according to the Minnesota Department of Health (MDH). Onset of illness ranged from August 4 to September 1, 2016. All five were hospitalized, and three of them are still in the hospital. All are over 50 years old.
MDH and the Hennepin County Public Health Department are currently investigating the outbreak to determine the source. Outbreaks of Legionnaires’ disease have been linked to cooling towers (air-conditioning units for large buildings), cooling misters, decorative fountains, plumbing systems, pools and hot tubs.
Symptoms of Legionnaires’ disease, also called Legionellosis or Legionella pneumonia, include muscle aches, chills, shortness of breath, headache, fatigue, loss of appetite and coughing. The time period from exposure (breathing in water contaminated with Legionella) to the onset of symptoms is usually 2-14 days. This is called the incubation period.
When 2 or more people diagnosed with Legionniares’ disease were in or near the same building prior to the 2-14 day incubation period, that building is usually looked at as a possible source of the Legionella bacteria that caused the outbreak.
“Once a building is considered a likely source of the Legionella bacteria, investigators take samples of water from the feature or system and test it for the presence of the bacteria,” says Elliot Olsen, an attorney who represents people sickened in these outbreaks. “A finding of Legionella bacteria in the water samples is evidence that water in the building is the source of the outbreak.”
Most cases of Legionnaires’ disease involve one person, which makes finding the source of the illness extremely difficult. It is only when there is a cluster of related illnesses, referred to as an outbreak, that investigators can pinpoint buildings more than one ill person visited prior to onset of illness.
This outbreak in Hopkins, located about 10 miles southwest of downtown Minneapolis, is the first one in Minnesota in 2016. “Minnesota typically sees 50 to 60 cases of Legionellosis each year. More than 60 cases have been reported in the state so far this year, mirroring a national increase in cases in 2016. No other clusters have been reported in Minnesota this year,” states the MDH news release about the outbreak.