Origin of Hepatitis Outbreak in Kids is Still Unknown

Health authorities have launched a global investigation into an outbreak of an unknown variant of the hepatitis virus that has been detected in children in a number of countries, including one in Germany.

There are more than 200 known cases, with 111 of them in the UK. But as more health authorities are alerted to the situation, cases are being detected around the world from Israel to Japan and Canada.

Many children have been hospitalized, 17 have required liver transplants and at least one child has died.

The European Center for Disease Prevention and Control (ECDC) issued a report into the situation on Thursday and told DW that details, such as the country of origin of the child who died, as well as whether they had been immunocompromised or undergone a liver transplant, remained confidential.

Cases have been detected across the world. Many have been serious, requiring hospitalization

In the United States, Wisconsin health authorities were investigating a potential second death, according to an alert issued on Wednesday.

Earlier in April, a large hospital in the US state of Alabama reported cases of five children who had experienced significant liver damage, including three with acute liver failure, who had also tested positive for adenovirus. The hospital later identified four additional pediatric patients with hepatitis and adenovirus infections going back to October 2021.

The hepatitis outbreak in the UK

A technical briefing released Monday by UK health authorities noted that out of 80 cases there, 43 of the children had recovered or been discharged, 38 were still in hospital or had an "unknown" discharge status and that none had died so far.

The children were not testing positive for any typical strains of hepatitis — types A, B, C, D or E. Kids aged one month to 16 years of age have been identified with the illness, but the majority of cases have affected kids under the age of five.

The UK report seemed to show strong evidence that the adenovirus, a common childhood virus, may play a role in this outbreak of hepatitis. Of 53 UK patients tested for adenovirus, 40 tested positive.

Possible explanations for the outbreak

UK officials have five working hypotheses for what is causing the outbreak.

The first and most likely cause, according to the UK report, is the existence of a "cofactor" that is making normal cases of the adenovirus more severe in children.

Cofactors can be a number of things: A lack of prior exposure to the adenovirus during the pandemic, a prior COVID infection, a COVID coinfection, or a toxin, drug, or environmental factor.

The report said it was also possible, but less likely, that the children are being infected by a new variant of the adenovirus, some other novel pathogen, or a new COVID variant.

It noted that it may not necessarily be a virus that is causing the illness and that it could instead be an unknown environmental factor. Vaccines have been ruled out.

Increase in adenovirus cases

Adenovirus cases in children aged between one and four are currently higher in the UK than they have been over the past five years, the report said.

Between November 2021 and March 2022, approximately 200-300 cases of adenovirus were reported per week. That is compared to 50-150 cases per week in the pre-pandemic period and less than 50 cases per week between March 2020 and May 2021.

The increase in adenovirus infections in the younger age groups began in November 2021, the report said.

Most patients presented with jaundice-like symptoms, said ECDC director Andrea Ammon at a press conference.

Jaundice causes a yellowing of the skin and eyes, followed by vomiting and other gastrointestinal problems. The symptoms are similar to those in a common adenovirus infection, Ammon said.

But some patients had also experienced acute liver failure, requiring emergency liver transplants, which is not a common response to an adenovirus infection.

What should I watch out for?

Richard Pebody, who leads a World Health Organization high-threat pathogen team in Europe, said on Thursday that parents of young children should not panic. Such cases were still very rare, Pebody said.

Parents should, however, stay alert for signs that their child was developing symptoms like jaundice: Yellow eyes and skin and/or dark urine.

"Then clearly they need to contact a healthcare professional," Pebody said at a press conference.

The ECDC report also cautioned parents to look out for vomiting, abdominal pain and pale stool.

Case numbers likely to rise

Researchers and doctors with knowledge about the situation believe that as awareness of the outbreak increases, case numbers will rise as well. But that may not be because the illness is spreading, but rather because doctors are checking their files and connecting details about the outbreak to old cases and patients whose diagnoses were unclear.

It's a process that begins with doctors recognizing unusual cases when they see them.

William Irving, a professor of virology at the University of Nottingham, said that when his hospital saw its first case, doctors chalked it up as an unusual event.

And unusual events need to get reported, too.

"We do our tests and we don't find a cause and hopefully the child gets better and goes home," Irving said. "And you scratch your head and say 'Well, that was an interesting case. I wonder what it was.' And we don't do anything more. That's happening all over the country. Each center is getting one, maybe two cases; you don't recognize that there is an incident until all of those get reported centrally."

When a Scottish team of doctors found eight case reports of kids with acute hepatitis over a short period of time, they contacted the health authorities, which triggered an alert. Once that alert was triggered by UK health officials, more cases started coming in.