Her 17-year-old son was despondent on the call, wondering how much longer he could avoid the coronavirus that made Bon Air Juvenile Correctional Center in Virginia the scene of the nation’s worst known outbreak at a prison for youths.

The teen was nervously awaiting the results of his second coronavirus test as resident after resident fell ill around him. The first — negative — came after a fever.

Prison officials had stopped visitors, suspended schooling, ended counseling and locked at least some teens in their cells 23 hours a day to stem the outbreak, the mother said. Still, it wasn’t enough.

The mother said her son’s cellmate, with whom he shared a bunk bed, began showing coronavirus symptoms. Her son phoned her in a depression after undergoing yet another test.

“He said, ‘Mom, I just don’t know how to stay well anymore,’ ” the mother recalled. “That would break any mother’s heart, because I didn’t know what to tell him, either.”

He tested negative.

Nearly a quarter of the publicly reported cases of the novel coronavirus at U.S. youth detention centers are at this single facility outside Richmond, according to a tally maintained by The Sentencing Project. Bon Air houses roughly 190 male residents between the ages of 14 and 20 from across Virginia.

The unfolding medical crisis that has sickened 26 inmates and seven staff members is the very type that youth advocates have feared could sweep such centers. Even as thousands of adult inmates have been released to head off covid-19 behind bars, Virginia and some other states have been slow to release youth offenders, leaving conditions for a tinderbox, they say.

“This is a warning sign to other youth correctional facilities across the country. And what’s so tragic is that it was so predictable,” said Rachael Deane, the legal director for the JustChildren Program at Virginia’s Legal Aid Justice Center. “In correctional facilities . . . the virus spreads like wildfire.”

Deane said clients inside Bon Air “are reporting chaos.” The Legal Aid Justice Center wrote in a letter to prison officials this week that one had not been seen by a doctor despite having tested positive for the coronavirus, another had symptoms but couldn’t get a test, numerous residents diagnosed with covid-19 were not provided adequate information about the disease, some parents had not been informed about their child’s positive tests, and protective gear for residents was not adequate.

Another mother interviewed by The Washington Post said she had not been able to talk to her son on the phone for a month, communication issues that were mirrored in reports to the Legal Aid Justice Center. The problems, they say, are being exacerbated by a skeleton staff.

Greg Davy, a spokesman for the Virginia Department of Juvenile Justice (DJJ), wrote in an email that officials are preparing a response to the allegations laid out in the Legal Aid Justice Center’s letter.

“As always, DJJ’s top priority is protecting the health and safety of our residents and staff,” Davy wrote. “We will continue to work closely with [the Virginia Department of Health] as we respond to this pandemic.”

A tracker on the department’s website reported that as of Wednesday, 22 of the sickened inmates have recovered, while four are still in quarantine. All seven of the staff members who contracted covid-19 remain in isolation. A news release issued last week said 21 of the then 25 sickened residents showed no outward signs of illness, and four had symptoms “no more severe than a cold or flu.”

The department said all the inmates are receiving medical care and parents have been kept up-to-date about what is going on.

DJJ officials said the facility has taken a number of steps to stop the outbreak, including screening residents twice a day for fever, testing anyone who exhibits even mild symptoms, giving residents and staff cloth masks and instituting social distancing policies.

The first signs of trouble emerged at the beginning of the month. The DJJ reported on April 2 that two staff members who had little contact with residents tested positive for the coronavirus. On April 6, the department announced a resident had covid-19.

Last week, Valerie Slater, the executive director of the juvenile justice advocacy group Rise for Youth, said she filed a freedom of information request seeking more information about what was happening inside Bon Air since officials had not provided an update. Other advocates said the DJJ had rebuffed their requests for information.

On Friday, DJJ officials announced there were 25 cases of the coronavirus at Bon Air. The gap in reporting angered Slater and some parents.

“They went radio silent on the whole thing,” Slater said.

Department Director Valerie Boykin said in a news release that the facility had not released the number of cases sooner because of concern for the underage offenders’ privacy, but the DJJ’s thinking had evolved on the issue along with other juvenile justice agencies across the country.

Parents said the anxiety of a potentially lethal contagion combined with the extreme isolation of spending 23 hours a day in a cell is taking a toll on their children. Two parents said their sons are only let out an hour a day to take a shower, exercise and call loved ones. The measures have extended more than two weeks now. The Post generally does not name juvenile offenders.

The Legal Aid Justice Center said they had been in touch with five inmates who were being kept under 23-hour-a-day lockdown. DJJ officials did not respond to questions about how many residents were being kept under those conditions.

“You’ve already had your child taken from you, so you’ve gone through absolute hell,” the mother of the 17-year-old said. “Then they’re saying I can’t see my kid. All of the sudden, they’re locked inside their room for 23 hours. It’s almost too much.”

The mother said the family only learned of her son’s first coronavirus test because her husband was on the phone with him when medical staff showed up in protective gear to administer it. She was in disbelief they hadn’t been informed. DJJ officials said in a news release they are notifying parents of all positive tests.

A mother of a 19-year-old said her son suffered from mental health issues and had previously attempted suicide. She said she has only been able to communicate with him by letter and she thinks his counseling has stopped. So have the choir and piano lessons that she said gave him purpose.

“He’s written, ‘I don’t know how I’m going to get through it,’ ” the mother said. “That’s alarming and concerning, because it shows he’s not getting the social engagement. I’m not getting letters saying, ‘I talked to my therapist today.’ ”

Eight commonwealth’s attorneys — including four locally in Arlington, Alexandria, Fairfax and Loudoun counties — called on Virginia juvenile justice officials to release youth offenders who posed no safety risk and to halt new admissions on April 15.

Boykin, whose spokesman did not respond to a request to interview her, told NPR this week that the DJJ had released 14 juveniles from Bon Air and was planning to release another 10 soon. Bon Air is the state’s only youth prison. Boykin wrote in a letter that the department had released 22 youths from state facilities in March and was reviewing more than 25 other cases. The DJJ has the authority to release or divert some juveniles in its care, but others can only be freed by a judge.

Youth advocates said those numbers are too low. They say it is part of a national problem. Some states, like Michigan and Colorado, have moved to release juvenile prisoners in a coordinated fashion, but such actions have been piecemeal across the country. An Annie E. Casey Foundation survey of a sampling of facilities in 30 states found the number of youths in detention dropped 24 percent between March and April.

“The releases are happening sporadically in some counties in some states, but certainly not across the board,” said Liz Ryan, president of the Youth First Initiative. “We have been saying for a month coronavirus is the kind of thing that can spread rapidly and put kids’ lives at risk.”

Josh Rovner, a senior advocacy associate at the Sentencing Project, said 115 inmates and 209 staff members at juvenile detention centers across the country have tested positive for the coronavirus as of Thursday. The numbers include 12 at Swanson Center for Youth in Louisiana and five at the New Beginnings Development Center in the District.

But Rovner said the actual number of coronavirus cases is probably higher. Only four states have put out figures for coronavirus cases in juvenile detention centers, but even those numbers are not comprehensive, he said. He pointed out Louisiana’s figures don’t include group homes. He has found other cases by scanning media reports.

“We don’t have any sense of how widespread coronavirus is in juvenile facilities,” Rovner said. “The reporting is scant.”