UW Hospital now has 11 cases of Legionnaires’ disease

December 8, 2018 GMT

Eleven patients at UW Hospital have developed Legionnaires’ disease, apparently from the hospital’s hot water system, and four of them remain in the hospital, officials said Friday.

Six patients have been discharged or treated at outpatient facilities. One died, as officials said last week, when the outbreak was announced and the reported tally of cases was five.


The patient who died had been hospitalized for multiple, severe health problems and the death was not unexpected, spokeswoman Lisa Brunette said last week.

The additional cases identified this week also were not a surprise, and more could be found before Wednesday, officials said. That is the end of the incubation period for the bacteria, which are typically present in low concentrations in tap water and at high levels can cause potentially fatal pneumonia.

Dr. Nasia Safdar, medical director of infection control at UW Hospital, said last week that UW’s cases appeared to be linked to a decision last month to reduce water flow at the hospital during low-demand times. That can make the water system more vulnerable to infectious bacteria, she said. Regular flow has been resumed, she said.

Last week, the hospital extensively chlorinated its water system, a process called “hyperchlorination,” to kill the bacteria. Testing so far has shown the expected reduction in the bacteria, officials said Friday. Monitoring at multiple sites continues.

“We are confident the hyperchlorination worked as expected,” John Marx, UW Health senior infection control practice specialist, said in a statement Friday.

The hospital is working with the Wisconsin Division of Public Health and the Centers for Disease Control to test its water and verify its system is safe, officials said.

SSM Health St. Mary’s Hospital, which confirmed having a Legionnaires’ case last week, hasn’t had any more cases, spokeswoman Lisa Adams said Friday. The St. Mary’s patient contracted Legionnaires’ in the community, not in a health care setting, Adams said last week.

UnityPoint Health-Meriter has not had any recent Legionnaires’ cases, spokeswoman Leah Huibregtse said Friday.


Legionnaires’ spreads in airborne droplets from hot water. The bacteria is mostly problematic for people with chronic diseases or who are already ill.

Until last month, UW Hospital hadn’t had any cases of Legionnaires’ acquired at the hospital in 23 years, the hospital said last week. Safdar attributed that to a copper-silver ionization system that disinfects the water.

Nationwide, about 6,100 cases of Legionnaires’ disease were reported in 2016, according to the Centers for Disease Control and Prevention. That figure is likely an underestimate, as many cases go undiagnosed.

About one in 10 people who get sick from Legionnaires’ disease will die, the CDC says. Among people infected at hospitals, nursing homes and other health care facilities, roughly one in four will die, the agency said last year.

Legionnaires’ is named for a 1976 outbreak at an American Legion convention in Philadelphia that hospitalized more than 200 people and killed 34.