By Associated Press
Recent genetic analysis has turned up no evidence that a single new mutant version of the virus is to blame, said Dr. Umesh Parashar, chief of the CDC group focused on viral gut diseases.
Adenovirus infections are not systematically tracked in the U.S., so it’s not clear if there’s been some recent surge in virus activity. In fact, adenoviruses are so common that researchers aren’t sure what to make of their presence in these cases.
“If we start testing everybody for the adenovirus, they will find so many kids” that have it, said Dr. Heli Bhatt, a pediatric gastroenterologist who treated two Minnesota children with the liver problems.
One was a child who came in nearly five months ago with liver failure. Doctors couldn’t figure why. Unfortunately, “not having a cause is something that happens,” Bhatt said. Roughly a third of acute liver failure cases go unexplained, experts have estimated.
Bhatt said the second child she saw got sick last month. By that time, health officials had been drawing attention to cases, and she and other doctors began going back and reviewing unexplained illnesses since October.
Indeed, many cases added to the tally in the last few weeks were not recent illnesses but rather earlier ones that were re-evaluated. About 10% of the U.S. cases occurred in May, Butler said. The rate seems to be relatively flat since the fall, he added.
It’s possible that doctors are merely discovering a phenomenon that’s been going on for years, some scientists said.
Another possible explanation: COVID-19.
The CDC recently estimated that, as of February, 75% of U.S. children had been infected by the coronavirus.
Only 10% to 15% of the children with the mysterious hepatitis had COVID-19, according to nasal swab tests given when they checked into a hospital, health officials say.
But investigators are wondering about previous coronavirus infections. It’s possible that coronavirus particles lurking in the gut are playing a role, said Petter Brodin, a pediatric immunologist at Imperial College London.
In a piece earlier this month in the medical journal Lancet, Brodin and another scientist suggested that a combination of lingering coronavirus and an adenovirus infection could trigger a liver-damaging immune system reaction.
“I think it’s an unfortunate combination of circumstances that could explain this,” Brodin told the AP.
Butler said researchers have seen complex reactions like that before, and investigators are discussing ways to better check out the hypothesis.
He said it was “not out of the realm of plausibility, at all.”
A Case Western Reserve University preprint study, which has yet to be peer reviewed, suggested children who had COVID-19 had a significantly higher risk of liver damage.
Dr. Markus Buchfellner, a pediatric infectious diseases doctor at the University of Alabama at Birmingham, was involved in the identification of the first U.S. cases in the fall.
The illnesses were “weird” and concerning, he said. Six months later, “we don’t really know exactly what we’re dealing with.”