One baby died and a further nine were admitted to hospital in an “unusual” cluster of heart infections in south Wales and southwest England, according to health officials.
Late on Tuesday night, the World Health Organisation said there had been a rise in severe myocarditis – a potentially deadly inflammation of the heart – in newborns and infants between June 2022 and March 2023.
A total of 15 babies – 10 in Wales, five in England – presented with the condition during this period, the WHO said. Of these, nine tested positive for an enterovirus – a common pathogen which can cause respiratory illness, hand, foot and mouth disease, and viral meningitis. In very rare instances, young babies can develop myocarditis.
The prevalence of cases in the UK peaked in November, the WHO said, adding that the risk to public health remains low.
“The reported incident represents an increase in both the number and severity of enterovirus infections in infants under the age of one month,” the WHO said in Tuesday’s announcement. Only one case had been identified in Wales in the six years prior to 2022.
Paediatric review of ICU babies
“Although enterovirus infections are common in neonates and young infants, the reported increase in myocarditis with severe outcomes in neonates and infants associated with enterovirus infection is unusual,” the agency said.
In the South Wales area, 10 babies received hospital treatment for enterovirus and myocarditis, one of whom died, Public Health Wales said earlier this month. All were aged under one month.
The UK Health Security Agency (UKHSA) said a “higher than average number of cases” of enterovirus had been observed in “very young babies” in Wales over the autumn and winter months.
Dr Shamez Ladhani, a consultant paediatrician at UKHSA, said officials were “investigating the situation in England to see if any similar cases have been observed here and whether there are any factors driving the increase in cases.”
The Telegraph understands that paediatricians across England have been asked to review the babies in intensive care to determine whether there is a broader outbreak, as the UK does not have routine surveillance in place for enterovirus-linked myocarditis.
Professor Paul Hunter, an expert in medicine at the University of Anglia, suggested there was no cause for concern.
“The big problem with these types of cluster is knowing whether this represents a real change or a random clustering with little long term importance,” he said. “Most but not all apparent clusters do not go onto pose a consequential threat to public health.
“Nevertheless, you cannot afford to assume that they will not progress and you have to investigate them.”
‘An extremely rare occurrence’
Dr Penny Ward, a visiting professor in pharmaceutical medicine at Kings College London, said health officials will investigate whether “there is a change in pathogenicity” of the enteroviruses found in the recent cases.
She said it “is quite possible” that the uptick in myocarditis cases was driven by a “larger scale outbreak of enterovirus infections – as we have seen quite a number of viral infections increased in frequency since Covid became less of a problem, but as we do not routinely look for these viruses in the population at large it's difficult to know.”
Welsh health officials are investigating whether the cases in Wales and England are linked, as they have emerged in two geographical clusters.
At the start of May, the country’s health minister, Eluned Morgan, said doctors have been asked to consider whether babies presenting with sepsis – a life-threatening reaction to an infection – could have myocarditis, but stressed “this is still an extremely rare occurrence”.
Experts say that a child may have sepsis if he or she: is breathing very fast; has a fit or convulsion; looks mottled or pale; is very lethargic or difficult to wake; and feels abnormally cold to touch. Parents should call 999 if their child is presenting with these symptoms.
The current investigation into enteroviruses and myocarditis is similar to the UKHSA’s enquiries into an unusual hepatitis outbreak in children last year, which was eventually traced to an adenovirus.
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