CDC Alert on Adenovirus and Hepatitis in Kids: What Experts Say You Should Know

9 cases of hepatitis, or liver inflammation, have been reported in Alabama and two have been identified in North Carolina

NOTE: Watch interviews with experts as they discuss what parents need to know on NBC 5 at 4 p.m. Tune in live on TV and in the player above.

The Centers for Disease Control and Prevention on Thursday issued a public health alert to physicians nationwide, asking doctors to be on the look out for unusual cases of severe liver disease in children, but how worried should parents be?

The agency said in its advisory that nine cases of hepatitis, or liver inflammation, have been reported in Alabama in children aged 1 to 6, and NBC News reports an additional two have been identified in North Carolina, according to the state's health department.

Dozens of cases have been reported in recent weeks in children in Britain and across Europe. The usual viruses that cause infectious hepatitis were not seen in the cases, and scientists and doctors are considering other possible sources.

Here's what you should know.

What is hepatitis?

Hepatitis is "inflammation of the liver that causes liver cell damage and if severe, can interfere with the normal function of the liver," according to Lurie Children's Hospital.

Some severe cases can lead to liver failure or possibly even death.

One of the most common causes of hepatitis is viral infection, according to the hospital.

“Mild hepatitis is very common in children following a range of viral infections, but what is being seen at the moment is quite different," said Graham Cooke, a professor of infectious diseases at Imperial College London. Some of the children in the U.K. have required specialist care at liver units and a few have needed a liver transplant.

The liver processes nutrients, filters the blood and fights infections. The infections caused symptoms like jaundice, diarrhea and abdominal pain. Hepatitis can be life-threatening if left untreated.

What are the symptoms to watch for?

"So the the symptoms of hepatitis in childhood can be vague at first - abdominal pain, loss of appetite, severe fatigue - but then, as it progresses, the children do start to have dark urine, pale stools, yellowing of the whites of their eyes," said Dr. Estella Alonso, a hepatologist at Lurie Children's Hospital in Chicago. "These are the things that parents notice. And if parents do notice that they should seek medical attention from their pediatrician or in an emergency or urgent care setting as soon as possible."

According to Lurie Children's Hospital, the most common symptoms of acute hepatitis include:

  • Flu-like symptoms
  • Fever
  • Nausea and/or vomiting
  • Decreased appetite
  • Not feeling well all over
  • Abdominal pain or discomfort
  • Diarrhea
  • Later symptoms include dark-colored urine and jaundice (yellowing of the skin and eyes). The symptoms of hepatitis may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.

The hospital notes that symptoms will likely vary by child.

What's causing the hepatitis infections?

While it's unclear what's causing the illnesses, a leading suspect is an adenovirus.

There are dozens of adenoviruses, many of them associated with cold-like symptoms, fever, sore throat and pink eye. U.S. authorities said the nine Alabama children tested positive for adenovirus and officials there are exploring a link to one particular version — adenovirus 41 — that’s normally associated with gut inflammation.

"So far it's unclear if the cause of this is all of this adenovirus 41," said Dr. Sharon Welbel, director of hospital epidemiology and infection control at Cook County Health. "For some other adenovirus there's certainly... it's been found in these kids and in a good portion of the kids in Britain, but it's also very common so I can't say for sure cause and effect. It's certainly a possible cause."

The CDC's advisory Thursday urges pediatric doctors to consider adenovirus testing.

Public health officials ruled out any links to COVID-19 vaccines, saying none of the affected children were vaccinated.

Have any infections been detected in Chicago or Illinois?

Experts say no such cases have been reported in Illinois or Chicago.

"We normally see between three to seven cases of severe hepatitis per year in the Illinois region," Alonso said. "We saw our usual rate of hepatitis cases this winter, but did not attribute any of them to adenovirus. We have not yet seen a severe case of hepatitis associated with adenovirus, but of course, we see a lot of adenovirus infection."

Welbel also said she it not aware of any reports of such cases in the area.

What's the difference between an adenovirus and coronavirus?

Adenoviruses and coronaviruses are both considered by health experts to be "common respiratory viruses." Each have several different strains, or types of the virus, with some types causing more severe illness than others.

"Coronavirus is a respiratory illness. Adenovirus is a respiratory illness as well," Alonso said. "It's transmitted in very much the same way as coronaviruses, but they're two very distinct viruses. Adenovirus is not associated with these severe respiratory symptoms in immune competent children. The adenovirus has not been associated with a inflammatory condition after the infection, the way coronavirus has been associated with the MIS-C diagnosis. But both can be circulating in the community at the same time and both are transmitted the same way. They're just two very distinct viruses."

How worried should you be?

The WHO noted that although there has been an increase in adenovirus in Britain, the potential role of those viruses in triggering hepatitis is unclear. WHO said there were fewer than five possible cases in Ireland and three confirmed cases in Spain, in children aged 22 months to 13 years.

The U.N. health agency said that given the jump in cases in the past month and heightened surveillance, it was “very likely” more cases will be detected.

Still, experts say the risk of severe hepatitis in healthy children remains rare.

"It's still very unusual, you know," Welbel said. "So far we've seem very, you know, a very small handful of cases, some of those cases were severe and a couple did require liver transplant in the U.S., but so far it's still what I would call rare."

What can you do to prevent it?

Experts say the public health protocols in place from coronavirus are the best measures for preventing adenovirus as well.

That includes washing hands properly, avoiding close contact with people who are sick, staying home when you are sick, covering your cough or sneeze, disinfecting surfaces and keeping hands away from faces and eyes.

"Those are just the basic public health precautions," Alonso said. "If a child or a friend, a sibling member has a viral gastroenteritis with vomiting or diarrhea, that child should be kept to themselves not attending playdates not attending school, so that the virus doesn't spread. Because our thinking is that this adenovirus may actually spread in several children where they don't have hepatitis, but then in certain individuals, it causes an infection that does become the hepatitis. So in general, it'd be good to practice public health measures that reduce the spread of adenovirus in general in our community."

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