NEW YORK (AP) – Health officials remain perplexed by mysterious cases of severe liver damage in hundreds of young children around the world.
The best available evidence points to a fairly common stomach bug that isn’t known to cause liver problems in otherwise healthy kids. That virus was detected in the blood of stricken children but – oddly – it has not been found in their diseased livers.
“There’s a lot of things that don’t make sense,” said a virus researcher Eric Kremer at the Institute of Molecular Genetics of Montpellier.
As health officials in more than a dozen countries look into the mystery, they are asking:
– Has there been some surge in the stomach bug – called adenovirus 41 – that is causing more cases of a previously undetected problem?
– Are children more susceptible due to pandemic-related lockdowns that sheltered them from the viruses kids usually experience?
– Is there some mutated version of the adenovirus causing this? Or some other not-yet-identified germ, drug or toxin?
– Is it some kind of haywire immune system reaction set off by a past COVID-19 infection and a later invasion by some other virus?
The United States (US) Centers for Disease Control and Prevention (CDC) and investigators around the globe are trying to sort out what’s going on.
The illnesses are considered rare. CDC officials last week said they are now looking into 180 possible cases across the US.
Most of the children were hospitalised, at least 15 required liver transplants and six died.
More than 20 other countries have reported hundreds more cases in total, though the largest numbers have been in the United Kingdom (UK) and US.
Symptoms of hepatitis – or inflammation of the liver – include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, light-coloured stools, joint pain and jaundice.
The scope of the problem only started to become clear last month, though disease detectives say they have been working on the mystery for months. It’s been maddeningly difficult to nail a cause down, experts said.
Conventional causes of liver inflammation in otherwise healthy kids – the viruses known as hepatitis A, B, C, D and E – didn’t show up in tests. What’s more, the children came from different places and there seemed to be no common exposures.
What did show up was adenovirus 41. More than half of the US cases have tested positive for adenovirus, of which there are dozens of varieties. In a small number of specimens tested to see what kind of adenovirus was present, adenovirus 41 came up every time.
The fact that adenovirus keeps showing up strengthens the case for it playing a role, but it’s unclear how, CDC’s Deputy Director for Infectious Diseases Dr Jay Butler, told The Associated Press.
Many adenoviruses are associated with common cold symptoms, such as fever, sore throat and pink eye. Some versions – including adenovirus 41 – can trigger other problems, including inflammation in the stomach and intestines.
Adenoviruses previously have been linked to hepatitis in children, but mostly in kids with weakened immune systems.
Recent genetic analysis has turned up no evidence that a single new mutant version of the virus is to blame, said Chief of the CDC group Dr Umesh Parashar focussed on viral gut diseases.
Adenovirus infections are not systematically tracked in the US, 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 a pediatric gastroenterologist who treated two Minnesota children with the liver problems Dr Heli Bhatt.
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”, Dr Bhatt said.
Roughly a third of acute liver failure cases go unexplained, experts have estimated.
Dr 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 per cent of the US cases occurred in May, Dr Butler said.