An outbreak of Legionnaires’ disease in Wisconsin has been linked to a decorative water wall in a hospital lobby, according to a study published Tuesday that suggested the popular architectural feature can pose dangers in a health-care setting, especially for people with weakened immune systems.

In 2010, eight people contracted the severe and potentially life-threatening form of pneumonia caused by the bacteria. None had been admitted to the Milwaukee-area hospital at the time of exposure. But they all had walked by the water wall in the main hospital lobby, researchers said.

The disease is spread through inhalation contact with contaminated water sources.

One person who got sick was a delivery man. Three others were picking up medication at the hospital pharmacy. Three were outpatients. And one man was waiting to pick up his wife.

“He really enjoyed sitting next to the water wall,” said Thomas Haupt, a Wisconsin health division epidemiologist and lead author of the study. “These water walls are indeed very beautiful, but they’re very risky.”

All eight either had underlying medical conditions or other factors that increased their risks of getting Legionnaires’ disease. Three were hospitalized in intensive care and were on mechanical ventilators; all eight survived.

The study, published online in Infection Control and Hospital Epidemiology, is the second documented outbreak of Legionnaires’ disease in a health-care setting associated with a wall-type water fountain, a design that is increasingly popular in hospitals, hotels, spas and other public settings, the study said. In 2007, two cancer patients at the National Institutes of Health in Bethesda were diagnosed with the disease after being exposed to a contaminated wall-type water fountain.

Decorative water fountains and water walls can be soothing and calming, so many hospitals and clinics included those amenities as a way to be more patient-friendly, said Jan Patterson, a professor of medicine and infectious diseases at the University of Texas Health Science Center at San Antonio.

But the problem is, even with regular cleaning and testing, “it’s possible for legionella to accumulate,” said Patterson, who is also president of the Society for Healthcare Epidemiology of America. “I guess the takeaway here is that if you have any underlying conditions, you should avoid walking by them or stay as far away as possible.”

As for hospitals and other health-care facilities, “they should avoid having these in their facilities altogether,” she said.

When the fountain was first suspected as the source of the Wisconsin outbreak, the hospital shut down the water wall and turned it into a planter. No known additional cases of Legionnaires’ disease occurred after that. Many other health-care facilities in Wisconsin shut down or removed their decorative fountains, the study said.

Every year, the federal Centers for Disease Control and Prevention receive reports of about 3,000 people diagnosed with Legionnaires’ disease. But experts say that many more cases go unrecognized and between 8,000 to 18,000 wind up in the hospital, according to Lauri Hicks, a CDC medical epidemiologist and specialist on Legionnaires’. More than 10 percent of cases are fatal.

Some of the most common symptoms, such as shortness of breath, cough and severe fatigue, are also associated with pneumonia, she said.

The Wisconsin study, she said, is a “good reminder that in settings where you have people with increased risk of getting Legionnaires’ disease, you should be considering carefully the management of any of your water systems that these persons could be exposed to.”

CDC experts have been working with a professional organization, the American Society for Heating, Refrigerating and Air Conditioning Engineers, to come up with a standard practice for building managers and owners to prevent the disease, she said.

Inpatient facilities with fountains, or any center that takes care of people with weakened immune systems, such as nursing homes, should be conducting regular assessment for Legionnaires’ disease, she said.

The water in fountains or water walls is often an ideal breeding ground for bacteria because it is warm or at room temperature and because the recirculating water can stagnate. In addition, fountains develop scum, “and the bacteria like to live in that slime layer that forms on fountains, in whirlpools, even in your shower,” Hicks said.

Fountains can also create bacteria-bearing aerosols as water sprays or cascades down walls or rocks.

The fountain at the Aurora St. Luke’s South Shore hospital was installed in 2008. All visitors using the hospital main entrance passed by it on their way to the information desk. Water flowed down a tile wall about 8 feet wide by 5 feet high, and through a bed of decorative rocks that rested on a spongelike foam material.

The water collected in a trough at the bottom of the fountain, beneath the rocks and foam, and an electric pump recirculated it to the top of the water wall.

Health officials found that the water was kept warm by two heat sources: an electric fireplace on the opposite side of the same wall that housed the fountain and low-voltage flood lights in the ceiling and in the water trough.

Although hospital staff performed weekly and monthly maintenance, “it’s very difficult to clean those things out,” Haupt said. A sampling of a 3-inch by 4-inch piece of the foam material found it had more than 1 million bacteria, he said.