Doctors believe the unusual outbreak of acute hepatitis among children may have peaked in the UK, as work continues to understand the cause of the mysterious disease.
Figures released on Friday by the UK’s Health Security Agency show 197 children have been diagnosed with unexplained acute hepatitis this year, with 11 becoming so sick that they need a liver transplant. Nobody died in the UK.
The health agency launched an investigation in April after hospitals reported a rise in acute hepatitis cases in children with no known cause. Normally, UK hospitals see around 20 cases a year not caused by common hepatitis viruses, but this year cases are about 10 times higher.
The latest report from the UKHSA shows that while new cases are still emerging, the rate appears to have slowed. “Potential delays in reporting mean that the rate of new cases is uncertain, although the current rate is more consistent with stability than exponential growth,” the report states.
Scientists studying outbreaks believe that adenovirus, a common infection that can cause colds, vomiting and diarrhea, may be involved in outbreaks, but the virus does not usually cause hepatitis in healthy children.
Tests on sick children showed that 68% were positive for adenovirus, mostly in the blood. But levels of adenovirus and other respiratory viruses rose to extraordinarily high levels in the spring as Covid restrictions eased, meaning the infection was widely spread in the general population.
DNA studies are now underway to see if infected children have a genetic susceptibility to hepatitis, or whether the type of adenovirus identified in most children, known as adenovirus 41F, has mutated into a form that can lead to disease in some children. One possibility is that the infection may trigger an abnormal immune response in some children, which attacks liver tissue.
“This could be a very, very common infection with one or more viruses, and the vast majority of us don’t even know we’ve had it, but there may be a genetic predisposition that means some children continue to have a disease,” said Calum Semple, a professor of child health and outbreak medicine at the University of Liverpool”.
Tests on liver tissue from children who had transplants did not reveal a direct cause of the damage. Professor Semple said there was no indication that the coronavirus, which was detected in 15% of cases, was directly involved, although an indirect effect had not been ruled out. There is no link to coronavirus vaccines. The majority of cases are in children under the age of five, who are too young to be vaccinated with the injection.
The involvement of adenovirus is the “main contender”, said Will Irving, professor of virology at the University of Nottingham, but many factors may contribute to the wave of cases. He added that the spring rise in cases may simply be more than what hospitals have seen before, with the increase being driven by high levels of the virus in the community.
Although the UKHSA is still searching for the cause, the agency has ruled out a link to pet dogs. Questionnaires filled out by affected families found that about 70% of the children had been in contact with dogs, but “extended investigations” found nothing to indicate a problem. “There is no indication of the role of dogs who have children with acute hepatitis,” Professor Semple said. “We can put that to bed now.”
There are still cases to come, but the UK appears to be on a downward trend, said Dr Tasos Grammaticopoulos, Consultant Pediatric Hepatology and Emeritus Lecturer at King’s College Hospital. “It looks like we’ve passed the peak,” he added.