Pet dogs are being probed as a potential cause of a mysterious hepatitis outbreak striking children across the world.
Health chiefs claim a ‘high’ number of the sickened children, who are aged 10 and under, come from families which own dogs or have had ‘dog exposures’.
The UK Health Security Agency (UKHSA), tasked with hunting down why dozens of children have developed the unusual type of liver disease, said the ‘significance of this finding is being explored’.
Officials did not explain how dogs could potentially be to blame.
Experts said the link was a ‘bit far-fetched’ given how common dog ownership is in the UK.
Meanwhile, officials today revealed another 18 youngsters have been struck down with the illness, bringing the UK’s total to 163 since January. Eleven have needed a liver transplant.
Nearly 300 cases have now been detected across the world, figures suggest. One death has been confirmed, while four are under investigation. But none of these are in the UK.
Scientists have been left puzzled over what is causing the illness — with the usual hepatitis A, B, C, D and E viruses excluded from laboratory test results.
Health chiefs believe the culprit may be an adenovirus. However, investigations are ongoing because they usually cause colds and stomach bugs.
Two strains of adenovirus are known to infect dogs, including one which causes infectious hepatitis. The other is one of the pathogens that triggers ‘kennel cough’.
The World Health Organization said earlier this week that nearly 300 cases had been detected globally. One death has been confirmed while four are under investigation. But none of these are in the UK
Health chiefs claim a ‘high’ number of the sickened children, who are aged 10 and under, come from families which own dogs or have had ‘dog exposures’. The UK Health Security Agency (UKHSA), tasked with hunting down why dozens of children have developed the unusual type of liver disease, said the ‘significance of this finding is being explored’
The UK had detected 163 confirmed and possible hepatitis cases among under-10s by May 3, which were not caused by the usual hepatitis A to E viruses. Of these, 118 cases are resident in England, 22 in Scotland, 13 in Wales and 10 in Northern Ireland
As of May 3, there were 118 cases confirmed in England, none of which are linked with each other. Some 40 cases in the country are waiting to be confirmed (grey bars). Nearly six in 10 cases are among children aged three to five
The report also revealed that adenovirus continues to be the most commonly detected virus amongst the youngsters with hepatitis. Blood tests from 126 of the affected children in the UK showed 91 were carrying it (72 per cent). And the UKHSA noted that some who tested negative only had throat and faecal tests rather than the gold-standard blood test
Q&A: What is the mysterious global hepatitis outbreak and what is behind it?
What is hepatitis?
Hepatitis is inflammation of the liver that is usually caused by a viral infection or liver damage from drinking alcohol.
Some cases resolve themselves, with no ongoing issues, but a fraction can be deadly, forcing patients to need liver transplants to survive.
Why are experts concerned?
Hepatitis is usually rare in children, but experts have already spotted more cases in the current outbreak than they would normally expect in a year.
Cases are of an ‘unknown origin’ and are also severe, according to the World Health Organization. It has caused up to two deaths and 18 liver transplants.
How widespread are cases?
The inflammatory liver condition has been spotted in around 300 children aged between one month and 16 years old.
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Fewer than five
*cases in Canada and Illinois, Wisconsin and New York are still yet to be confirmed
What are the top theories?
Experts say the cases may be linked to adenovirus, commonly associated with colds, but further research is ongoing.
This, in combination with Covid infections, could be causing the spike in cases.
The WHO reported adenovirus has been detected in at least 74 of the cases. At least 20 of the children tested positive for the coronavirus.
British experts tasked with investigating the spate of illnesses believe the endless cycle of lockdowns may have played a contributing role.
Restrictions may have weakened children’s immunity because of reduced social mixing, leaving them at heightened risk of adenovirus.
This means even ‘normal’ adenovirus could be causing the severe outcomes, because children are not responding to it how they did in the past.
Other scientists said it may have been the adenovirus that has acquired ‘unusual mutations’.
This would mean it could be more transmissible or better able to get around children’s natural immunity.
New Covid varying
UKHSA officials included ‘a new variant of SARS-CoV-2’ in their working hypotheses.
Covid has caused liver inflammation in very rare cases during the pandemic, although these have been across all ages rather than isolated in children.
The UKHSA has noted environmental triggers are still being probed as possible causes of the illnesses.
These could include pollution or exposure to particular drugs or toxins.
Three quarters of the UK’s 163 hepatitis-stricken children have tested positive for adenoviruses, analysis shows.
But the UKHSA admitted it was possible the others could also have had the virus because of the way the testing is carried out.
Some of the negative cases had only looked for adenovirus in respiratory and faecal samples, even though it is mainly detected in the blood.
Academics believe lockdowns may have weakened the immunity of children and left them more susceptible to the virus.
But the UKHSA also acknowledged that an ‘exceptionally large’ adenovirus wave could be why the condition is appearing more frequently than expected, or it may be even be down to a mutated form of adenovirus.
Hepatitis is usually rare in children, but experts have already spotted more cases in the UK since January than they would normally expect in a year.
Cases are of an ‘unknown origin’ and are also severe.
Another theory is that children may have been battling the adenovirus at the same time as Covid, or that the complication may be long Covid.
However, health officials have ruled out the Covid vaccine as a possible cause because the majority of the ill British children haven’t been vaccinated due to their young age.
Top experts fear health chiefs won’t understand what’s behind the peculiar pattern — which has been sickened 200 children worldwide since March — for months.
Dr Meera Chand, director of clinical and emerging infections at the UKHSA, said the link with adenovirus is being ‘rigorously’ assessed.
She warned parents to stay on the lookout for hepatitis symptoms, while noting the likelihood of their child being affected is ‘extremely low’.
Jaundice — the yellowing of the skin and whites of eyes — is the most common sign, followed by vomiting and pale stools.
UKHSA officials trawled through questionnaire responses from affected families and found 70 per cent — 64 of 92 respondents — owned a dog or had been exposed to a dog.
The health chiefs admitted the finding may be lucky because pet dog ownership is ‘common in the UK’.
Around half of UK adults own a pet, figures suggest.
But it is investigating if the dog link is of any significance.
Dr Chand said: ‘It’s important parents know the likelihood of their child developing hepatitis is extremely low.
‘However, we continue to remind everyone to be alert to the signs of hepatitis – particularly jaundice, look for a yellow tinge in the whites of the eyes – and contact your doctor if you are concerned.
‘Our investigations continue to suggest that there is an association with adenovirus and our studies are now testing this association rigorously.
‘We are also investigating other contributors, including prior SARS-COV-2, and are working closely with the NHS and academic partners to understand the mechanism of liver injury in affected children.’
Health chiefs are also hopeful that hepatitis cases have peaked, noting that there has been ‘some apparent reduction in confirmed cases in the past two weeks’.
However, the downturn may be due to reporting lags.
Scotland is continuing to log cases and there are a ‘substantial’ number of suspected cases in England that are being investigated, the UKHSA said.
The report also revealed adenovirus continues to be the most commonly detected virus amongst the youngsters with hepatitis.
Blood tests from 126 of the affected children in the UK showed 91 were carrying it (72 per cent).
And the UKHSA noted some who tested negative only had throat and faecal tests, rather than the gold-standard blood test.
‘It is therefore not possible to definitively rule out adenovirus in these cases,’ the agency said.
The UK update comes after the WHO this week said nearly 300 probable cases of hepatitis have been spotted in 20 countries.
Most of the cases have been detected in the UK (163) and US (27), which have some of the strongest surveillance systems.
The liver inflammation condition has also been spotted in Spain (22), Israel (12), Italy (9) and Denmark (6).