“Her eyes didn’t look like they were attached to her head anymore,” her mom, Kelsea Schwab, told CNN Chief Medical Correspondent Dr. Sanjay Gupta. “They were just rolling all over.

“She would still ask for bananas and ask for juice and ask for snuggles, kind of like she’s still there, but not really,” she said.

Seemingly out of nowhere, Baelyn’s liver had become so damaged that it could no longer clean ammonia out of her blood.

She’s part of a nationwide investigation by the US Centers for Disease Control and Prevention into recent cases of sudden severe hepatitis — or swelling of the liver — in 109 children in 25 states and territories. There are roughly 340 more children with similar cases around the world, the, European Centre for Disease Prevention and Control reported on Wednesday.

In the US, five of the children have died, and 15 have needed liver transplants.

Globally, including the US, there have been 11 deaths, and in the UK, 11 children have received liver transplants.

Like Baelyn, most of the children are young — under the age of 5. Many had no apparent health problems before showing signs of liver injury: They lost their appetites. Their skin and eyes began to turn yellow, symptom called jaundice. Some had dark urine and cloudy gray stool.

Two-year-old Baelyn Schwab is part of an investigation into recent cases of severe hepatitis among children.

Within a week, Baelyn had gone from running around her family’s farm in Aberdeen, South Dakota, playing with her sister and watching the children’s TV show “Blippi,” to a room in the pediatric intensive care unit at M Health Fairview Masonic Children’s Hospital in Minneapolis, where doctors were checking her blood four or five times a day, watching to see if her liver might recover. But it didn’t.

“Slowly watching her deteriorate like that, like her muscles, she would start shaking, and she had a hard time sitting up, and she couldn’t hold her head up, and just watching her go through that was like, ‘this is not my kid,’ ” Schwab said. “Like, am I ever even going to get her back?”

‘This is very unusual for us’

The liver has a number of important roles. It controls clotting factors in the blood. It contributes to the body’s immune response. It also filters out ammonia that is produced when bacteria in the intestines break down protein. When the liver is working as it should, ammonia gets changed into urea and flushed out of the body as urine.

Normal blood levels of ammonia are between 25 and 40, says Dr. Srinath Chinnakotla, surgical director of the liver transplant program at M Health Fairview Masonic Children’s Hospital.

What parents should know about the increase in unexplained hepatitis cases in children

“Anything over 100, you can get symptoms,” Chinnakotla said. “So what happens is that the brain starts swelling, and then they become comatose. And if you don’t transplant them appropriately, they can have brain damage” — or, worse, die.

Baelyn’s ammonia level had gotten as high as 109.

“That’s when I got a little bit nervous,” Chinnakotla said. At levels that high, “the kidneys shut down; the patient becomes comatose. And then you know you are behind the eight ball.”

People waiting for liver transplants can get so sick that they can’t withstand the procedure. That’s the situation Chinnakotla did not want Baelyn to be in.

Chinnakotla, a world-renowned surgeon and one of only a few dozen specialists who perform pediatric liver transplants in the United States, put Baelyn on a transplant waiting list.

Children automatically get highest priority, a status called 1A, reserved for those who have hours or days to live.

In an average year, he might do this surgery on 10 children. Most of them need new livers because they were born with autoimmune diseases or birth defects. Maybe one might need a new liver because of sudden liver failure.

“And this year,” he said, “we’ve already seen two children with liver failure and transplanted two children with liver failure. This is very unusual for us.”

A medical mystery

Disease detectives aren’t sure what’s causing these hepatitis cases.

Dr. Jay Butler, the CDC’s deputy director of infectious diseases, said at a briefing last week that the agency was “casting a wide net” to look at all possible exposures and associations.

Even before this outbreak, sudden liver failure cases like this often puzzled doctors.

“I’ve taken care of a half-dozen or a dozen kids where we did our best look, and we never found a cause for why their livers just failed,” said Dr. Beth Thielen, a pediatric infectious disease specialist at the University of Minnesota who has been treating Baelyn. “And some of them got better, or some of them went to transplant, so this happens at some base frequency.

“And I think what has drawn people’s attention is that this seems to be happening more frequently, and there does seem to be this association with adenovirus — not every child, but there does seem to be a larger percentage of these cases that do seem to be associated with adenovirus,” Thielen said.

More than half the children in the CDC’s investigation — including Baelyn — have tested positive for adenovirus 41, a type of virus that ordinarily causes stomach upset and cold-like symptoms. It has never before been linked to liver failure in otherwise healthy children.

Doctors aren’t sure how this virus might be involved. It’s not clear whether it could be directly damaging the liver or setting off an unusual immune response that’s causing the body to attack its own tissues. Another possibility is that adenovirus has an accomplice, a co-factor that could be genetic, environmental or even infectious, that in tandem is leading to these extreme outcomes.

Baelyn tested positive for adenovirus, which is being studied for a potential link to unusual cases of hepatitis.

Because these cases are happening amid the pandemic, researchers are also looking for any link to the virus that causes Covid-19. Some of the children in the investigation, including Baelyn, have a history of Covid-19 infection, but others don’t. Investigators says it’s too early to know whether it’s a factor.

Baelyn tested positive for adenovirus in her blood but not in her liver tissue. It’s a pattern doctors have noticed in other children, too. In Baelyn’s case, her doctors say her liver may have been so damaged by the time they tested it that they couldn’t find the virus. They’ve sent tissue samples to the CDC for more specialized testing.

The adenovirus infection created a quandary for Baelyn’s doctors. Ordinarily, adenovirus infections are relatively mild-mannered, and the link to liver failure in these children is still uncertain.

But what if it was the culprit?

Patients who get organ transplants must have their immune function turned down with powerful medications so their bodies won’t reject the new organ. The drugs might diminish Baelyn’s immune function, allowing the smoldering infection to reignite and burn out of control.

If the adenovirus had destroyed one healthy liver, could it attack another? Would they give her a new liver only to see that one ravaged, too?

They could treat the adenovirus, but the drug they would need to use — cidofovir — is toxic to the kidneys.

It was a risk.

With so much uncertainty still about the cause of these infections, should they use this powerful antiviral in a medically fragile child?

They decided to try it but to watch her carefully. They didn’t have time to wait for the infection to clear. Her liver was failing too quickly.

A stealthy disease

On Friday, April 22, Baelyn woke up covered in itchy red welts. Her mom had seen it before: hives.

“She has a pretty long list of allergies,” Schwab said. “She’s always had a snotty nose, since the beginning of time.”

The family has been working with an allergist, so they took her to the doctor, who gave her a shot of epinephrine and sent her to the local emergency room for monitoring. The hives cleared up.

The next day, her mom thought she could see a little yellow in the whites of Baelyn’s eyes, but she chalked it up to the epinephrine.

On Sunday, she thought they were a little more yellow, and she texted a photo to her mother. “Do you see the yellow, or am I crazy?”

After a few symptoms emerged, Baelyn was flown to a hospital in Minnesota.

On Monday, her mother-in-law mentioned that Baelyn’s eyes looked yellow. “OK, I’m not crazy,” Schwab thought. She made a doctor’s appointment for the next day.

“She was still acting fine. She still acted perfectly healthy. Her skin wasn’t yellow, just her eyes,” Schwab said.

The doctor drew blood and, later that afternoon, called them with dire news.

“You have to get to the city now. You don’t have time to wait,” they were told.

They didn’t even have the five hours it takes to drive to Minneapolis. Schwab raced from work to the hospital, and the family was flown to the city by helicopter.

Just the day before, Schwab had been talking with her mother, a lab technician, about the mysterious cases of hepatitis that were being investigated in kids. She never imagined that Baelyn might be one of them.

Schwab and her husband, who doesn’t want to be named for this story, also have a 4-year-old daughter, Kennedy. They farm 1,000 acres in Aberdeen, South Dakota, where they grow hay and raise sheep. She used to travel to Fargo each week for a job managing dental offices, but she left that job recently because of a family tragedy.

In December, her youngest daughter, Laramie, died of sudden infant death syndrome just 12 days before her first birthday.

Then, tragedy seemed to compound itself.

Weeks after losing Laramie, Schwab went to the doctor with pain in her abdomen. She thought it was stress from grief, but it was her appendix. While she was recovering from surgery for that, the whole family got Covid-19 — possibly from Laramie’s funeral. Then, two of her husband’s grandparents died within weeks of each other.

“I think I’ve cried so much in the last five months, I don’t have any tears left,” Schwab said. “To be back in the hospital setting again, it’s like replaying in your head all day.”

Schwab shared photos and videos but asked that CNN not film Baelyn, who was taking powerful drugs to weaken her immune system and being weaned off painkillers. Her mother didn’t want the world to see feisty, independent Baelyn as weak and sick.

A lifesaving gift

The liver that saved Baelyn’s life came in a picnic cooler, packed in ice.

It had been drained of blood, washed and preserved in a solution. These preparations blanch the normally deep burgundy tissue to pale fleshy color that’s not quite tan and not quite pink. In the surgeon’s gloved hands, it could be mistaken for an uncooked chicken breast.

Although bioengineers have created machines that can temporarily take over the work of the heart, the lungs and even the kidneys, there is no device or procedure that can fill in for the liver. When it fails, patients need a transplant.

“The interesting thing about liver, it’s just such a humble organ,” said Dr. Heli Bhatt, a pediatric gastroenterologist at M Health Fairview Masonic Medical Center who is treating Baelyn.

CDC releases new clinical details in cases of unusual hepatitis in children

It does its job without much fuss until it just can’t anymore. Bhatt says someone can lose a lot of liver tissue and not know until it’s almost too late.

When Baelyn came to the hospital, doctors did a liver biopsy to see the damage from the inside. They found something called precursor cells, a sign that the liver was trying to repair itself. They tried to buy Baelyn a little time to see if the organ might recover.

“Kids that present like that, a lot of times, do turn over within like two to three days and then do fine and not require a liver transplant,” Bhatt said.

They took her blood every four hours around the clock, watching for any change in her liver enzymes, her clotting factors, her ammonia levels.

But over the next few days, the numbers did not improve. They decided to put Baelyn on the transplant list and to screen her parents to see if they might be able to be living donors.

“She kept appearing really well, you know, till she was not well and needed to be intubated,” Bhatt said. “That’s the thing about the liver, that you need to have extremely low suspicion to be very carefully monitored in the hospital and sent to ICU at the first drop-off deterioration so that you can get the best care.”

Baelyn had been at the top of the transplant list for three days when the offer came for a liver from a 16-year-old in Texas. It was just in time.

Masonic dispatched a team, including a surgeon, to Texas. They removed the organ, turning one family’s heartbreak into another’s hope.

Hooking up the washing machine

Chinnakotla’s team carefully divided the liver, teasing apart its internal structures so it would be small enough to fit into a 2-year-old’s body and still work. They raced back to Minnesota.

Transplants are long, painstaking surgeries under even the best of circumstances. “With children, you get one good shot. So you want to do it slowly and carefully, at least that’s my philosophy,” Chinnakotla said.

When Chinnakotla explains liver transplants to patients, he tells them it’s like hooking up a washing machine: There are two hoses coming in, like one for the cold water and one for hot water, and a hose to drain fluid out.

CDC investigating more than 100 cases of unexplained hepatitis in children, including 5 deaths

The hot water hose is the hepatic artery that supplies blood to the liver and pancreas. He compares the cold water tube to the portal vein, which drains blood from the intestines. The drainage hose is a large vein called the inferior vena cava that carries filtered blood back to the heart, where it can be re-oxygenated.

He has to clamp off these vessels to stop the flow of blood, remove the old liver, replace it with the donor liver, reattach the blood vessels and finally — in a moment that always makes him hold his breath — release the clamps. It’s in that instant that he knows whether the operation was successful, if the liver once again flushes with color, back to its deep dark red.

When he opened Baelyn’s body, it was clear that her liver was heavily damaged. One side was bulbous and swollen, and there were dark areas of dead tissue. Under a microscope, doctors could see that much of the tissue was destroyed. Normal livers are spongy; Baelyn’s was tough and rubbery, another sign of disease.

There was also a surprise. Instead of one vessel supplying the liver with blood, there were two, each about half the normal size.

When he tried each of these smaller vessels to the new liver, it didn’t work. “There wasn’t enough flow,” he said. Finally, he used blood vessels harvested from the donor to create a special graft, or bridge, between the aorta and the liver.

“When I did that, it looked good,” he said.

Even the downsized liver was still too large for tiny Baelyn’s body, so Chinnakotla left her incision open, covered with mesh, for a day or two so her care team could check on the transplant more easily and drain the wound.

The operation lasted from 8 in the morning until 4:30 in the afternoon on May 5.

“She came back from surgery, and she wasn’t yellow anymore,” Schwab said. It was an astonishing change.

But Baelyn is not out of the woods and won’t really be for another year, Bhatt says.

She will stay in the hospital for at least two more months, her mom said. After that, she will be monitored frequently while her body and her new liver get used to each other.

The long road to recovery

Baelyn is awake. She is being weaned off the medications that control her pain. She is getting physical therapy to help restore the strength she lost from being in bed. Her doctors say she is recovering remarkably fast.

For the Schwabs, life is still minute-to-minute. They are managing with the help of friends and family and donations from a GoFundMe page for Baelyn.

“I think we tried our hardest to make sure we were sleeping. We definitely have not slept or ate since the transplant, just anticipating that something bad is going to happen or has happened,” Schwab said.

And they’re still working through some grief over the fact that their once-healthy rough-and-tumble 2-year-old needed a liver transplant at all.

Baelyn is in the hospital in Minnesota while she recovers following a liver transplant.

Schwab hopes that by telling their story, they can help other families avoid the same fate.

“I really want to spread awareness about this because I don’t want another parent to be in this situation,” she said. “It’s terrifying. It’s horrible. It’s dramatic. And not very many families can handle the strain that this puts on them and emotionally, physically, mentally, financially.”

She wants people to watch for any symptoms — like any yellowing of the skin or eyes, dark urine, cloudy gray stool, fatigue, fever, nausea, vomiting or a loss of appetite — and take immediate action if they appear.

“I feel like if somebody would have done a story a couple months ago, I would have definitely jumped on it.”

Their doctors, though, say the family did everything right.

“Mom is a fighter, too,” Bhatt said. “She is an amazing advocate for Baelyn. She’s so attentive to all her care.”

“Going through your kid almost died and needed a transplant in such a short amount of time, and yet to understand all the medical stuff and ask good questions, it’s not something that I personally could have done,” Bhatt said. “Hats off to them.”

CNN’s Nadia Kounang contributed to this story.