Thousands of elderly residents of Minnesota nursing homes are being confined to their rooms, cut off from their relatives and gripped by fear of an invisible virus. Those who fall prey to the illness risk dying alone.

But for weeks, Minnesota residents have been kept in the dark by state health officials about which senior care facilities have reported cases of COVID-19, the respiratory disease caused by the virus.

Responding to mounting public criticism, the Minnesota Department of Health on Saturday released the names of 32 nursing homes and assisted-living facilities facing outbreaks of COVID-19. The data offer a revealing glimpse into how far the disease is spreading in senior living communities across the state and the types of facilities most exposed. So far, 13 residents of long-term care facilities have died from the disease, accounting for more than half of the 24 deaths across the state.

As public health experts had warned, nursing homes with a poor track record at controlling infections appear to be particularly vulnerable to the virus' spread. Two-thirds of the Minnesota nursing homes identified with a COVID-19 case have been cited by federal regulators for violating at least one infection control measure over the past four years, according to a Star Tribune analysis of federal health data. At least two of the nursing homes with COVID-19 cases have been fined for serious health and safety violations, health records show.

The list released Saturday includes 11 nursing homes and assisted-living facilities in Hennepin County, as well as four each in Ramsey and Washington counties. The facilities include Walker Methodist Health Center and the Villa at Bryn Mawr, both in Minneapolis; two assisted-living facilities, in Edina and White Bear Lake, operated by the Waters, and facilities in Bloomington and Arden Hills operated by Presbyterian Homes and Services, a large nonprofit provider. The outbreaks are spread over facilities in more than a dozen counties.

That rate of spread has raised concerns about whether the industry's safety measures — bans on visits, isolation and health screenings of staff — are rigorous enough. Other states have taken more dramatic measures. In Connecticut, for instance, public health authorities have proposed separating infected patients in "coronavirus-only" facilities to protect healthy residents. And this week, the nation's largest nursing home association urged providers to start creating separate wings, if not entire buildings, to care for the projected surge of infected patients. Moving patients to separate, coronavirus-only facilities would pose risks to those infected, but might help states get ahead of the problem before clusters emerge in more nursing homes, said Toby Edelman, senior policy attorney with the Center for Medicare Advocacy in Washington, D.C. "Right now, it's safe to say that what is being done is not adequate," she said. "Nursing home residents are like sitting ducks. If you separate them, they have a better chance of survival."

More than 80,000 Minnesotans live in nursing homes and assisted-living facilities. The CDC has said that older people and those with chronic health conditions, such as heart and lung disease, are at a higher risk from the virus. In nursing homes, many patients have weakened immune systems and live in close proximity. The median age of Minnesotans who have died from the virus is 84.

So far, Minnesota's senior care facilities have been spared the sort of severe outbreaks that have rampaged through nursing homes in other states, infecting scores of residents and staff and leaving many dead. At one facility in Washington state, two-thirds of the residents and staff tested positive for the virus and at least 37 have died. Still, there are signs that the disease is spreading within Minnesota's senior living communities: Nine facilities have more than two cases, one facility has eight cases.

Even before the coronavirus arrived on U.S. shores, nursing homes had struggled to comply with basic infection protection protocols.

Two of the nursing homes on the state's list have been fined over the past three years for serious health and safety violations. Rochester East Health Services was fined more than $130,000 in 2018 after a health inspection found that four diabetic residents were not receiving proper care and that providers had not adequately protected one patient from choking and another from falling. Presbyterian Homes of Arden Hills was fined in August 2017 after an inspection found that a resident broke a leg while being improperly transferred.

"You layer a pandemic on facilities that are chronically understaffed and struggling with infection control, and that's a very, very challenging situation," said Joseph Gaugler, a professor who focuses on long-term care and aging at the University of Minnesota's School of Public Health.

Over the past month, limited public information about which Minnesota senior care facilities had outbreaks had been a source of anxiety. State health officials encouraged nursing homes and assisted-living facilities to inform families of any outbreaks. But there are no consistent, industrywide standards.

Some Minnesotans said they discovered they had a loved one living in a facility where coronavirus was found only after the state Health Department posted the facility names on its website.

The department classifies an "outbreak" broadly as occurring in any facility that has had even a single case of a resident, staff member or visiting contractor testing positive for COVID-19.

Walker Methodist Health Center, a large Minneapolis nursing home with 250 residents, has had one resident and one former employee test positive for COVID-19.

"The resident is in isolation in their room, and doing quite well," spokeswoman Sarah Benbow said. Benbow said that the staff member's last day working at the center was March 17, and the person tested positive 10 days later. Benbow said the facility is "very hopeful" that means the employee didn't infect anyone at work.

The center is following all CDC guidelines, including restricting visitors, monitoring residents daily and screening employees before they enter the building, she said. Benbow said the families of all the residents received a phone call about the situation. "Since we have shared the news, we have been overwhelmed by an outpouring of support," she said.

State health officials and nursing home industry representatives had expressed concern that releasing the names of facilities with outbreaks would be counterproductive. Families might rush to move their loved ones to other facilities presumed to be safe, and that might cause the virus to spread more rapidly, they said.

So far, those fears have proved groundless. Nursing homes and assisted-living providers that have notified families of COVID-19 cases have not seen an exodus of residents, in part because of concerns that the virus is so widespread that moving an aging relative will not necessarily insulate them from the virus. Even now, a month after the first case was reported in Minnesota, some 80% of the 865 Minnesotans sickened by the virus live in private homes and apartments. Long-term care facilities account for less than 6% of all cases.

Daniel Fenner said his 91-year-old mother called him last week to inform him that someone had the virus at her facility, the Waters of White Bear Lake. The facility confirmed that a resident had tested positive and been sent to the hospital. It also outlined a series of protective measures, including daily health screens of residents and a requirement that all staffers wear masks.

Fenner said he concluded that "nowhere is safe" from the virus. "The whole world is going through this, and my mother's little world is not that different from what the rest of us are going through," he said. "The biggest thing is that people in these facilities need to know that people on the outside care."

Staff writer Christopher Snowbeck contributed to this report.