A healthy baby died at 1 month old after contracting a severe version of a common virus. It's now showing up in multiple states.

• A dangerous type of parechovirus is circulating in the US, infecting newborns.
• At least one baby died in Connecticut, and the CDC has tracked the virus in "multiple states."

When baby Ronan was born on May 21 this year, he was a "healthy, full-term," 8 pound-5 ounce boy.

But about 10 days after Ronan was born, his mother, Kat DeLancy, started noticing some redness on his face. Perhaps he'd been in the sun too long.

He had no fever, and "seemed otherwise perfectly fine," DeLancy told Insider.

Just a couple days later, Ronan was irate.

"Crying and crying and crying," she said.

His chest turned bright red, he stopped eating much of anything, and seemed sleepy and low-energy.

Doctors suspected it could be colic, but "I just had a bad feeling," DeLancy said. "He didn't look good to me."

In the middle of the night, the worried mom rushed her newborn to the hospital. There, a provider noticed he looked pale. Clinicians stuck an oxygen saturation monitor on his foot, then on his tiny toe. The reading, which should register around 95% in a healthy person, first read 70%, then 20%.

Immediately, the infant was whisked away and intubated. Practitioners found out Ronan had been having seizures. Brain scans revealed some damage, possibly repairable. But it took about four days of tests to really figure out what was wrong. Ronan had a parechovirus.

"No one seemed to believe that he had a virus," DeLancy said. Perhaps it was a genetic condition, some doctors speculated. "One infectious disease doctor actually said that they thought it might be head trauma. They were asking me questions like, had I ever dropped my baby? Had anybody else held my baby?"

Initially, DeLancy was assured that her baby would fully recover from the viral illness. After all, most babies and toddlers get this virus at some point. But that's not what happened to Ronan.

Most kids get a parechovirus infection at some point, and many never know it

Parechovirus are part of a large family of viruses (Picornaviridae) that cause a wide array of viral illnesses ranging from the simple, common cold (rhinovirus) to crippling polio.

Most children will get some kind of parechovirus before they start grade school. Usually, the illness clears up on its own in about seven days. It is rarely tested for, unless a patient is severely ill.

"We'll say, 'Oh, this is probably a parecho or a coxsackievirus,'" Dr. Andrew Wong, a primary care physician with Hartford Healthcare, said. "We'll give them Tylenol, hydration, Advil, and they'll get better in a week."

But infectious disease doctors nationwide are growing increasingly worried about one particular type of parechovirus called PeV-A3, which is associated with severe disease in very young infants.

The Centers for Disease Control and Prevention put out a special alert to healthcare providers nationwide Tuesday, urging them to test for parechovirus in children who have unexplained fevers, seizures, loss of appetite, irritability, rashes, and sleepiness.

'Hot, red, angry babies'

Dr. Claire Bocchini, an infectious disease specialist at Texas Children's Hospital who has treated babies that are critically ill with parechovirus, says with A3, one of the most "classic" symptoms of severe illness can be seizures, a tell-tale sign that the virus has invaded the brain.

"You can have babies who are very, very fussy, irritable, then become very sleepy, aren't eating well," she said.

They may have sepsis, with the virus impeding the baby's heart and liver function. Eventually, parechovirus A3 can kill or seriously brain damage newborns.

Other children never show outward symptoms of the infection and develop normally. Most of the high risk cases happen in babies, like Ronan, who are less than one month old. But even a six month-old can be susceptible to a bad case of parechovirus.

In 2017, pediatricians and infectious disease experts in New Zealand wrote a paper in a prominent microbiology journal, acknowledging that parechovirus "is increasingly being recognized as a potentially severe viral infection" in babies.

"In young infants, the typical clinical presentation includes fever, severe irritability, and rash, often leading to descriptions of 'hot, red, angry babies,'" they said.

Ronan never logged a fever, and his mother believes that was a big part of the reason it took providers so long to figure out what was going on.

"It took a lot of pushing and prodding and tests for them to find it in my son," she said. "And honestly, I don't think that they would've kept testing if I didn't keep just being annoying."

While there is no treatment for parechovirus, there are immune-boosting therapies often given to the most severe patients, including Ronan. Sometimes they work, and sometimes they don't.

Ronan didn't get better. The longer his infection wore on, the worse his brain damage became.

Scans showed to his mom near the end of his life showed "areas where there was actually no tissue anymore," she said. "They said his entire frontal lobe is basically gone. His entire parietal lobe is almost entirely gone."

There wasn't much left to do for the boy, who died at 34 days old.

Handwashing and avoiding kissing or sharing drinks is critical

Bocchini is careful not to blame parents when their kids get severely sick with parechovirus.

"I always tell parents that there's nothing that they can do to really prevent these infections when they happen," she said. Newborn immune systems, still developing, are highly susceptible to all kinds of viral problems.

Still, because people can shed parechovirus in their stool for up to six months after an infection, thorough handwashing is a critical piece of prevention.

"Soap and water for 20 seconds," Bocchini said. "After you go to the bathroom, after you change a diaper, before you eat, before you feed an infant, that's always important."

Because there isn't good surveillance or testing for this virus, it's unclear how common deadly infections like Ronan's really are. One 2010 autopsy study from Wisconsin showed a parechovirus present in at least 18 dead children in that state over a 17-year span, but it's unclear whether those viruses are what actually caused the infant deaths.

DeLancy, Wong, and Bocchini are all hopeful that more awareness and testing for the virus now will help providers get a better sense of the scope of the problem. That could lead to future antiviral treatments for the illness, rapid tests, or, one day, a vaccine for pregnant mothers.

"It's a very long term goal," DeLancy said, but she hopes in a decade or so, "they'll be able to give them a medication or something to treat it before it escalates to needing to go to the hospital."