A mysterious hepatitis outbreak in children has now spread to 10 states and at least a dozen countries. Public health experts are asking parents to pay attention but not panic as they try to find what’s causing so many children — the majority just toddlers — to become ill.

Hepatitis literally means liver inflammation. And there are always some cases of children with inflamed livers from various causes, including those caused by viruses. However, none of the children who have the mystery version have tested positive for viruses known to cause hepatitis A, B, C, D or E.

Experts believe an entirely different class of virus, the adenovirus, may be responsible. But while a number of the children have tested positive for a strain called adenovirus 41, it usually causes respiratory illness.

Liver inflammation from an adenovirus has, until now, been almost unheard of in children who did not have compromised immune systems. The new cases have all been reported in otherwise healthy children.

Still, at this stage of the public health investigation, adenovirus 41 is the virus of interest in the outbreak, which has sickened children between the ages of 1 and 16. Most of the cases have been on the younger side of childhood, among those ages 2 to 5. In three U.S. cases, children experienced liver failure; two required a liver transplant and one is still waiting for one. A child in Wisconsin died.

At the end of April, Medical News Today said nearly 200 cases had been identified in Europe, North America and Asia, with 17 requiring liver transplants worldwide. The outbreak was first reported in Scotland with the earliest case sometime in November 2021, but has been seen in about a dozen countries now. In the United States, cases have also been confirmed in Alabama, Delaware, Georgia, Illinois, Louisiana, Minnesota, New York, North Carolina and Tennessee.

While public health experts aren’t completely sure what’s causing the hepatitis outbreak, officials say it’s highly unlikely it’s linked directly to the pandemic. Although some of the children have had COVID-19, most of the children diagnosed with hepatitis have not had COVID-19.

And despite rumors to the contrary, the COVID-19 vaccines are not a suspect. None of the children with hepatitis were vaccinated — and most of them are too young to even be eligible, according to public health experts.

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Watching for cases

Most of the outbreak involves really little kids getting very sick, according to Utah state epidemiologist Dr. Leisha Nolen, who is both a physician and a Ph.D. “The most prominent thing is they come in with vomiting and diarrhea. But I think most parents know vomiting and diarrhea are very common in little kids. Most of the time, that’s nothing and I don’t think parents need to be concerned,” she said.

Jaundice, though — a visible, though sometimes slight, yellowing of the skin or whites of the eyes — indicates a liver problem. “That’s the kind of sign that we’re worried about,” said Nolen, who added that “certainly, if your kid was really sick, if your kid has that yellow skin color, you should talk to your doctor. It might not be the liver problem that’s happening. It might be something else.”

State public health experts and doctors who are apt to see cases in children have been asked to report hepatitis cases as part of nationwide disease surveillance of the outbreak. Parents and doctors are also being asked to watch for symptoms of hepatitis, including fever, fatigue, loss of appetite, nausea, vomiting, dark urine, light-colored stool, joint pain and jaundice, according to an alert from the Centers for Disease Control and Prevention.

Nolen said Utah health officials are tracking emergency room data. They’ve been looking back at the last five months (when the first cases were seen in the United Kingdom) to see if Utah emergency rooms are seeing an uptick in cases that might indicate an unusual pattern of liver inflammation cases.

“We aren’t seeing something suspicious that changed from what is a normal pattern. There are all sorts of random things that can happen that can cause people’s livers to have health problems,” she said.

Other states are doing similar surveillance to detect cases, which are then reported to the CDC, which looks for patterns and outbreaks regionally and nationally. But even in informal interactions with colleagues in the Mountain West, Nolen said concerning cases haven’t emerged.

“Certainly we're all looking really closely. Even here in Utah, we have a few cases in children; it’s normal to have a few cases of hepatitis every month or every few months. We’re just reviewing those really thoroughly to make sure there’s nothing usual about those compared to what happened last year,” Nolen told the Deseret News.

“While this cluster was surprising and alarming, we do not want this report and alert to cause a panic among the public,” said Henry Shiau, a pediatric liver specialist at the University of Alabama at Birmingham, where some of the pediatric hepatitis cases have been treated, in a news release.

“Diarrhea, vomiting and fever are very common symptoms in children, especially those who are in day care or in school. What is important is for parents and pediatricians to have awareness of the signs of liver disease, such as yellowing of the eyes and skin, and let us know so we can investigate further.”

Hard to sort out

Besides testing for the common hepatitis viruses — and not finding them — the children have been tested for other viruses. CNN reported recently that among nine young patients in Alabama, six tested positive for the Epstein-Barr virus. While that’s a pretty large share, in all of the cases the Epstein-Barr infections were known to predate the hepatitis.

Kids commonly pick up viruses and when the children were tested for a number of other viruses, some were found, including entrovirus/rhinovirus, metapneumovirus, respiratory syncytial virus and human coronavirus OC43. 

In its investigation, which is the longest-running in the outbreak, the Scottish National Health Service found little in common between the children’s hepatitis cases, besides the illness itself and the young age of the patients, who were on average 4 at the time of being admitted to the hospital. They came from different areas and were demographically diverse.

A CDC advisory says there are 50 distinct types of adenoviruses that can infect humans. There’s no specific treatment; doctors treat the symptoms. Adenoviruses typically cause respiratory illness, though they can also cause inflammation in the stomach and intestines or lead to pink eye and bladder infections. Liver disease has not been previously linked to adenovirus in healthy children.

Nolen said if the liver biopsies in Alabama had shown adenovirus 41, it would have been a slam dunk. And health experts continue to look for markers from different viruses to see what they suggest. But it will likely take more cases before medical experts are certain what’s causing the illness in kids or to place the blame solidly on adenovirus 41.

The World Health Organization reported that the adenovirus strain 41 was found in at least 70 cases, though it’s possible children had the strain in addition to the hepatitis, not because of it. That’s what investigators are trying to sort out.

Preventing hepatitis and other ills

There are steps that parents and others can take to help stop the spread of the liver-injuring virus — or other viruses, too. They are precautions that people should be taking anyway, especially with COVID-19 circulating, health experts emphasize:

  • Wash hands often with soap and water.
  • Avoid people who are sick. And stay away from others if you don’t feel well.
  • Cover coughs and sneezes.
  • Do not touch your eyes, nose or mouth, which are great entry points for viruses to get into the body. And teach young children not to touch them, either.

And if a child is unusually ill, has jaundice or symptoms persist, a doctor should be consulted. Regardless of its cause, diarrhea or vomiting that doesn’t resolve quickly can lead to dehydration, which can be dangerous.