The CDC is still looking for the cause of a mysterious liver disease in children

The search for the cause behind the cluster of mysterious and severe cases of hepatitis in young children continues.

Reports of potential cases have been pouring in since the Centers for Disease Control and Prevention issued a nationwide alert to doctors in April, asking them to be on the lookout for unexplained cases of liver inflammation in children.

These cases have not yet led to direct answers, but experts are confident that further research over the coming months will bear fruit.

A total of 296 potential cases of unexplained hepatitis in young children have been identified so far, the CDC reported Friday. Most cases are not new; many have been identified retrospectively, with doctors dating back to October. And while the number may seem high, it has not exceeded the expected annual number of cases of severe pediatric hepatitis.

In fact, cases have been declining in recent weeks, according to Dr. Markus Buchfellner, a pediatric infectious disease researcher at the University of Alabama at Birmingham. Buchfellner first alerted the CDC to back-to-back unusual cases of pediatric hepatitis last year.

But falling case numbers don’t mean scientists are taking their eyes off the ball. The situation is “still alarming enough that we need to know more,” he said.

Most cases involved children under 5; the average age was 2 years old, the CDC reported. Nearly 90% of the children required hospitalization, 6% required a liver transplant and 11 children died.

None of the children tested positive for any of the common causes of hepatitis, including the viruses that cause hepatitis A, B and C. Hepatitis refers to inflammation of the liver in general and can have hundreds of causes, including other viruses, toxins, and foods. poisoning.

In 224 of the cases, the patients were tested for an adenovirus infection – a virus considered the main suspect. Just under half, 45%, tested positive.

Adenoviruses are common in children and can cause a range of symptoms, from the common cold and pink eye to vomiting and diarrhea. But they are not a known cause of severe hepatitis in healthy children.

The adenovirus is known to cause hepatitis in immunocompromised children, said Dr. David Sugerman, a physician with the CDC’s Division of Viral Diseases and author of the new report. But the recent surge of cases differs from cases in immunocompromised children in two ways, he said. First, they are found in children with healthy immune systems, and second, the virus has been found in stool and blood samples, but has not yet been detected in liver tissue.

“Pathology in Liver Tissue [in the new cases] is not what we usually see with adenovirus liver disease. That’s what’s different,” said Sugerman, who is also the deputy incident manager for the CDC’s Pediatric Hepatitis of Unknown Etiology Response Task Force.

According to the report, adenovirus was not the only virus detected in samples from children, although it was by far the most common. About 26% of children previously had Covid, and 10% tested positive for Covid at the same time as they had hepatitis. A smaller number of children had other viruses, such as RSV.

A misunderstood problem

It’s not uncommon for viruses to go undetected until they cause serious problems, said Dr. Alice Sato, a pediatric infectious disease specialist at Children’s Hospital and Medical Center in Omaha, Nebraska. For this reason, physicians do not have a clear understanding of how many adenoviruses, and which specific ones, are circulating in communities at any given time.

It’s possible, she said, that adenovirus infections in children with hepatitis are coincidental, given that the cases do not appear to be higher than pre-pandemic levels of pediatric hepatitis.

That said, “there’s enough suspicion that the CDC has enlisted the states to watch this very closely to see if this is really something so that we can prevent it,” Sato said. . “It’s not taking off like wildfire, but several states have reported cases that may be of concern.”

One theory is that adenovirus has always been a cause of pediatric hepatitis in some children, but because children weren’t socializing during the pandemic, they weren’t exposed to adenovirus early in life. According to Sugerman, most children are exposed to adenovirus before age 4. Quarantine has also interrupted the normal cycle of the virus – with things like influenza and RSV, which were previously considered winter viruses, now appearing in the summer months.

“There could be a quick re-exposure, and it’s possible it’s something that’s always been there, but we haven’t seen it before because there hasn’t been that re-exposure,” he said. he stated, noting that if re-exposure is the cause, it is not triggering a wave of hepatitis cases.

Still, Sugerman said acute liver failure in children isn’t well understood, and about 30% of cases historically have no known cause. “It is possible that the adenovirus was one of the causes of these cases which had not been detected before,” he said.

Sugerman said Covid infection does not appear to be an underlying cause of hepatitis, but the possibility is still being investigated.

Buchfellner, of the University of Alabama at Birmingham, said a link to the long Covid has not been completely ruled out, as experts have not yet been able to detect traces of the virus in the hepatic tissue.

“There are a lot of theories floating around as to why this happened, and we don’t have solid evidence to say one way or another,” he said. “What we were able to show is that something unusual is going on.”

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