Experts have described the outbreak of hepatitis in children under the age of 10 as “unusual and worrying”.
But while it is very serious for those youngsters who have had to undergo liver transplants, it is worth emphasizing that case numbers in the overall population are very small.
Fewer than 10 per cent of confirmed cases have received transplants, and the 108 confirmed infections represent a tiny proportion of that age group: 79 cases in England amounts to 7.7 per million children aged under 15, while 29 in the rest of the UK is roughly 16 per million in that same age group, according to Sheila Bird, former program leader at the MRC Biostatistics Unit, University of Cambridge.
Professor Bird said this discrepancy in case rates between England and the other nations suggested there might be some delayed reporting. However, these remain very small numbers.
With several countries worldwide now reporting cases, teams of scientists in the UK, US and at the World Health Organization are working on identifying a cause for the outbreak.
The leading hypothesis is adenovirus, which is a very common cold virus. For most people, including children, adenovirus does not cause serious illness. The UK Health Security Agency has advised that people observe normal hygiene measures such as thorough handwashing and disposing of tissues if they have a cold.
While one potential cause – a new variant of adenovirus – may sound alarming, it is not uncommon for the genomes of viruses to mutate; Sars-Cov2, the virus that causes Covid-19, has evolved many times since it first emerged more than two years ago.
However, unlike Covid, which is an RNA virus, adenovirus is a DNA virus – and therefore tends to evolve more slowly.
Professor Bird said the proportion of children needing liver transplants, while a minority, was still “remarkable.”
In a normal year, clinicians would expect to see 11 “super-urgent” – that is, due to sudden onset of disease – liver transplants in children. The fact there have been eight so far in 2022, with less than a third of the way through, is clearly a concern.
The good news is that doctors and parents will now be alert to any symptoms in children and treatments can be given rapidly if they become very ill.
Parents have been advised to look out for symptoms of hepatitis including dark urine, pale, grey-coloured faeces, itchy skin, yellowing of the eyes and skin (jaundice), muscle and joint pain, a high temperature, feeling and being sick, feeling unusually tired all the time, loss of appetite, and tummy pain.
Doctors have been told to lower their threshold for suspicious cases, which will also ensure any child with hepatitis symptoms can be seen quickly by a specialist.
Dr Zania Stamataki, associate professor in viral immunology at the Center for Liver and Gastrointestinal Research, University of Birmingham, said: “Liver inflammation (known as hepatitis) caused by adenovirus is uncommon in the young, with the exception of immunocompromised children.
“The rising incidence of children with sudden onset hepatitis is unusual and worrying. If an adenovirus is to blame, this could be a new variant of adenovirus that may cause liver injury in children with naïve/immature immune systems. But we need to know more to be sure.
“Alternatively, if adenovirus is the culprit for hepatitis in children that are otherwise well, we ought to look for other infections and environmental causes that could exacerbate adenoviral inflammation.”