JThe World Health Organization said on Saturday that 12 countries have reported at least 169 unusual cases of hepatitis in children, with 17 of those children having undergone liver transplants as a result. At least one child has died.
The European division of the WHO, which is leading the investigation into the mysterious outbreak, has urged countries to find, investigate and report similar cases.
“While the numbers aren’t large, the consequences have been quite severe,” Richard Pebody, who leads the high-risk pathogens team at the WHO’s European division, told STAT in an interview. “It’s important for countries to watch.”
Affected children range in age from 1 month to 16 years old, although the majority are under 10 and many are under 5, Pebody said.
Countries that have reported cases are UK (114), Spain (13), Israel (12), US (9), Denmark (6), Ireland (less than 5) , the Netherlands (4), Italy (4), France (2), Norway (2), Romania (1) and Belgium (1). Pebody would not say which country had reported a death.
The figures may already be out of date. The United States has seen 11 cases – nine in Alabama and two in North Carolina.
Alabama’s earliest cases date back to October and November 2021, the earliest known cases. Pebody said most of the others are newer. Scottish authorities – whose identification of a cluster of cases marked the first report published on these cases — reported 14 cases dating from January to mid-April.
Severe hepatitis in previously healthy children is not common. What makes these cases of severe liver inflammation more unusual is that they were not caused by the typical culprits – the hepatitis viruses labeled A through E which are the most common causes of the disease. .
Instead, suspicion focused on an unexpected suspect – an adenovirus, specifically adenovirus type 41. At least 74 of the affected children tested positive for adenovirus infection and molecular testing revealed evidence of adenovirus 41 in 18 of these children.
Both the UK and the Netherlands have reported that they are seeing an increase in the circulation of adenoviruses, adding to the evidence that these viruses may play a role.
But several issues complicate the picture.
Adenoviruses normally attack the airways, although some – including type 41 – can trigger gastroenteritis, an inflammation of the stomach and intestines that causes diarrhoea. Adenovirus 41 has been linked to hepatitis in immunocompromised children, but has not been observed to cause disease in previously healthy children.
While many children were infected with adenoviruses when they developed hepatitis, 20 of them had Covid-19 and another 19 were co-infected with adenovirus and SARS-CoV-2, the virus that causes the Covid.
Authorities have ruled out any possibility that Covid vaccines may have been implicated in these cases. The vast majority of children have not been vaccinated, according to the WHO statement.
Pebody said a number of hypotheses were on the table. Because the illness the children exhibited does not match what has previously been associated with adenovirus 41, scientists are studying the virus to see if it has undergone any changes that could explain the new behavior.
Another theory stems from the fact that these cases are being reported around two years into the Covid pandemic. Many affected children will have had fewer colds and other infections in the past two years, due to social distancing and wearing masks. This may have left them more susceptible to developing serious illness when they encountered germs. Hong Kong scientists reported last year that children were ending up in hospital with rhinovirus infections – colds – when schools reopened after months of closure.
The possibility that Covid-19 could play a role in this is also still on the table, Pebody said.
“At the moment, the main hypothesis seems to be that the adenovirus seems to play a role,” he said, while warning that “these are the very early days” of the investigation.