New York (AFP) – Health officials are still puzzled over the mysterious cases of acute liver damage in hundreds of young children around the world.
The best available evidence suggests a common stomach bug that is not known to cause liver problems in healthy children. This virus was detected in the blood of infected children, but strangely enough, it was not found in their diseased livers.
“There are a lot of things that don’t make sense,” said Eric Kremer, a virologist at the Institute for Molecular Genetics in Montpellier in France.
As health officials in more than a dozen countries consider the puzzle, they ask:
Has there been some rise in the stomach bug – called Adenovirus 41 – that has caused more cases of a previously undetected problem?
Are children more vulnerable to infection due to the pandemic-related lockdowns that protect them from viruses that children usually suffer from?
Is there a modified version of the adenovirus that causes this? Or some other as yet unrecognized germ, drug or poison?
Is it some kind of immune system reaction caused by a previous infection with COVID-19 and a subsequent invasion by some other virus?
The US Centers for Disease Control and Prevention and investigators around the world are trying to figure out what’s going on.
Diseases are rare. Centers for Disease Control and Prevention (CDC) officials said last week that they are now looking into 180 possible cases across the United States, most children have been hospitalized, at least 15 liver transplants have died and six have died.
More than 20 other countries have reported hundreds more cases in total, although the largest numbers have been in the United Kingdom and the United States
Symptoms of hepatitis — or hepatitis — include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, light stools, joint pain, and jaundice.
The scale of the problem only began to become clear last month, although disease investigators say they have been working to solve the mystery for months. Experts say it has been very difficult to pinpoint a cause.
The classic causes of hepatitis in healthy children — viruses known as hepatitis A, B, C, D and E — have not been shown in tests. Furthermore, the children came from different places and there seemed to be no common exposures.
What has emerged is adenovirus 41. More than half of the cases in the United States have tested positive for adenovirus, of which there are dozens. In a small number of samples tested for the type of adenovirus present, adenovirus 41 appeared each time.
The fact that the adenovirus has continued to emerge strengthens the case because it plays a role, but it’s unclear how, Dr. Jay Butler, the CDC’s deputy director for infectious diseases, 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 cause other problems, including gastroenteritis. Adenoviruses have previously been linked to hepatitis in children, but mostly in children with weakened immune systems.
Dr. Umesh Parashar, head of the Centers for Disease Control and Prevention (CDC) group focused on viral gut diseases, said recent genetic analysis has revealed no evidence that a single new mutated version of the virus is responsible.
Adenovirus infections are not systematically tracked in the United States, so it is not clear if there has been some recent rise in virus activity. In fact, adenoviruses are so common that researchers aren’t sure what to do to have them in these cases.
“If we start testing everyone for adenovirus, they will find a lot of children with it,” said Dr. Healy Bhatt, a pediatric gastroenterologist who treated two Minnesota children with liver problems.
One of them was a baby who came about five months ago with liver failure. Doctors couldn’t figure out why. Unfortunately, Bhatt said, “Having no reason is something that happens.” Experts estimate that approximately one-third of acute liver failure cases are unexplained.
Bhatt said the second child she saw fell ill last month. By then, health officials had drawn attention to the cases, and she and other doctors had begun going back and reviewing unexplained illnesses since October.
In fact, many of the cases that have been added to the tally in the past few weeks were not recent diseases, but earlier re-evaluated cases. About 10% of cases in the United States occurred in May, Butler said. He added that the rate appears to have been relatively flat since the fall.
Some scientists said it’s possible that doctors are just discovering a phenomenon that’s been going on for years.
Another possible explanation: COVID-19.
The Centers for Disease Control and Prevention recently estimated that, as of February, 75% of US children have contracted the coronavirus.
Health officials say only 10% to 15% of children with occult hepatitis have COVID-19, according to nasal swab tests taken when they are hospitalized.
But investigators are questioning previous infections with the Corona virus. It’s possible that coronavirus particles lurking in the gut play a role, said Peter Broden, a pediatric immunologist at Imperial College London.
In an article published earlier this month in the Lancet medical journal, Broden and another scientist suggested that a combination of the novel coronavirus and adenovirus infection could trigger an immune system reaction that’s harmful to the liver.
“I think it’s an unfortunate combination of circumstances that could explain that,” Broden told The Associated Press.
Butler said researchers have seen complex reactions like these before, and investigators are discussing ways to better verify the hypothesis.
He said it “wasn’t beyond reasonableness at all”.
A preprint study by Case Western Reserve University, which has not yet been peer-reviewed, indicated that children who contracted COVID-19 were more likely to have liver damage.
Dr. Marcus Buchfelner, a pediatric infectious disease physician at the University of Alabama at Birmingham, participated in identifying the first cases in the United States in the fall.
He said the illnesses were “strange” and worrying. Six months later, “We don’t know exactly what we’re dealing with.”
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