Health officials have received reports of hundreds of children in 33 countries, including the United States, diagnosed with acute hepatitis of unknown origin that is clinically more severe than previous similar cases.
The World Health Organization (WHO) said in a May 27 statement that it had received reports of 650 possible cases of acute hepatitis of unknown origin in children between April 5 and May 26, with the reports coming as researchers theorize about a link possible with COVID. -19.
"The etiology of this severe acute hepatitis remains unknown and under investigation," the health agency said. "Cases are more clinically severe and a higher percentage develop acute liver failure compared to previous reports of acute hepatitis of unknown etiology in children."
Another 99 cases were pending classification as of May 26, with the potential to bring the total number of cases to 749 if confirmed.
Nearly 60 percent of the reported cases were in Europe, with 222 from the United Kingdom alone. Of the 240 cases reported in America overall, 216 cases were recorded in the United States.
The Centers for Disease Control and Prevention (CDC) in late April issued a nationwide health alert for a group of nine children in Alabama identified with hepatitis and adenovirus infection, with no known cause.
The children were between one and six years old, all previously healthy, with five of them hospitalized with severe liver damage, including some with acute liver failure.
"Hepatitis A, hepatitis B and hepatitis C viruses were ruled out," the CDC said, adding that all children tested positive for adenovirus.
The agency urged doctors to be on the lookout for symptoms and report any suspected cases of hepatitis of unknown origin to the local health department. Typical symptoms are dark urine, loose stools, vomiting and jaundice.
Link to COVID-19?
The CDC later released a report saying none of the Alabama children tested positive for COVID-19 when they were taken to the hospital. The agency also said none of the children had a previously documented case of SARS-CoV-2, also known as the CCP virus, nor had they received the COVID-19 vaccine.
Some research suggests that a previously unknown infection with the SARS-CoV-2 coronavirus may be behind mysterious cases of severe hepatitis in children.
Children with COVID-19 are at significantly increased risk for liver dysfunction afterward, according to a report recently posted on medRxiv, which has not yet been peer-reviewed.
But most children with acute hepatitis – which is generally rare in that age group – do not report a previous SARS-CoV-2 infection. Instead, most of them were found to be infected with an adenovirus called 41F, which is not known to attack the liver.
A separate team of researchers suggests in The Lancet Gastroenterology & Hepatology that it is possible that the affected children, many of whom are too young to be vaccinated, may have had mild or asymptomatic COVID-19 infections that passed without were noticed.
One theory put forward by the researchers is that residual coronavirus particles in the gastrointestinal tract of these children may stimulate the immune system to over-react to adenovirus-41F by producing high amounts of inflammatory proteins that then damage the liver.
"We suggest that children with acute hepatitis be investigated for the persistence of SARS-CoV-2 in stool" and other signals that liver damage is occurring because the spike protein of the coronavirus is a "superantigen" that oversensitizes the immune system, the researchers said.
Other experts have theorized that, as a result of social distancing and other countermeasures associated with COVID-19, young children have had less chance of being exposed to adenoviruses, which would help build their immunity. In such cases, it is theorized that children's immune systems may respond to an adenovirus infection by overproducing inflammatory proteins.
More study is needed to confirm either theory, said Dr. Rima Fawaz, a pediatric liver disease specialist at Yale School of Medicine.
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