An unusual wave of baby deaths linked to a new strain of a normally harmless virus has sparked alarm in France.
Seven babies are known to have died after being infected with Echovirus-11, with two more still in hospital, according to a World Health Organization (WHO) alert.
Echovirus-11 belongs to family of pathogens called enteroviruses which, while normally only causing cold or flu-like symptoms in adults, can be dangerous to young children.
Health authorities are particularly concerned about the current cluster of cases due to their rapid onset of serious illness and high fatality rate unusual.
British experts said it was possible that Covid lockdowns could be partly to blame, as mothers lacking immunity from common bugs can pass this vulnerability on to their babies.
Enteroviruses usually cause only mild illness but tend to affect newborns and young children more severely than older children. They can trigger symptoms including a fever, runny nose, sneezing, cough, rash and muscle aches
The alert from France comes after the UK raised the alarm last month over an unusual cluster of enterovirus, caused by a different strain, left one baby dead and eight in intensive care.
French health authorities detected a total of nine cases of Echovirus-11 among newborns between July 2022 and April this year across three unnamed regions.
The babies, eight of which were born pre-term, experienced severe sepsis and multi-organ failure following infection, with seven dying as a result.
Three of the cases were recorded in 2023, with the rest occurring in 2022.
The newborns are believed to have caught the virus from their mothers by inadvertently swallowing infected bodily fluids during childbirth, the WHO said.
Genetic analysis of the Echovirus-11 strain behind the deaths suggests it is a new version of the virus which has not been recorded by global health authorities before.
The WHO report said although the possibility that the new strain could be deadlier couldn’t be ruled out, further research was needed.
‘Although higher pathogenicity of this new lineage cannot be excluded, the severity of infections may also be explained by the young age, prematurity, and the absence of maternal immunity,’ it read.
‘Further analyses are warranted to delineate the characteristics of this recombinant virus.’
However, the WHO added that, although based on the ‘limited’ information, the risk to the public by the cluster of cases is still considered to be low.
It also highlighted that as many countries don’t routinely report enterovirus infections, some cases may have slipped under the radar.
The WHO alert said the strain Echovirus-11 behind the newborn deaths in France appears to be new, with no previous record of it anywhere in the world
What is the situation?
More than a dozen young children in the UK have developed myocarditis (inflammation of the heart) alongside an enterovirus infection.
How many cases have been detected?
Ten cases have been spotted in South Wales and five have been detected in Southwest England between June 2022 and March 2023.
How many children have been hospitalised?
Eight youngsters were treated in intensive care, where they were intubated, put on a ventilator and received circulatory support.
Details of six cases are unclear, so the number may be higher.
Have any children died?
One child died before being transferred to tertiary care — part of a hospital that delivers highly specialist treatment.
However, a couple in South Wales have shared details of the death of their son Elijah, who died in similar circumstances.
As this death occurred in March 2022, out with the nine-month period defined by Public Health Wales, it is not being probed as part of the official cluster.
What is behind the outbreak?
Experts don’t know.
But health chiefs at Public Health Wales are investigating the reasons for the cluster of cases and to spot any others that may be reported in the coming weeks.
What’s the situation in France?
Health chiefs have identified a cluster of cases in newborns caused by a different type of enterovirus than the UK outbreak.
Seven babies have died as a result of the infection since June 2022 with two remaining in hospital.
The World Health Organization says a new strain of pathogen called Echovirus-11 is responsible.
No specific antiviral therapy is available for enteroviruses, so treatment focuses on preventing complications.
French authorities have urged medics to keep a watchful eye on newborns whose mothers may be ill with an enterovirus in response to the recent cases.
MailOnline understands that there are currently no signs of a similar cluster of Echovirus-11 infections in Britain.
However, UK health authorities have observed a string of unusual cases from a different enterovirus in the same period, which they are still investigating.
A total of 15 newborns in Wales and south-west England have been struck down with severe myocarditis — inflammation of the heart — since June 2022.
PCR testing of nine of the children confirmed they had coxsackie B3 or B4 — types of enterovirus.
Out of the affected babies, one died. Eight were treated in intensive care, where they were intubated, put on a ventilator and received circulatory support.
Details on the remaining six cases have not yet been published.
Myocarditis usually occurs following a virus. It is caused by the body’s immune system overreacting to being infected and causing inflammation, which can stay in the heart even after the virus has been cleared.
While some sufferers have no symptoms, it can cause chest pains, palpitations and shortness of breath.
The unwell children in the UK also presented with sepsis — which can kill within hours unless it is treated quickly. They were also less interested in eating and drinking.
Health authorities consider the two clusters of enterovirus clusters in the UK and France to be unrelated.
Previous unusual outbreaks of infectious disease among children, including Strep A last winter, have been blamed on lockdowns potentially weakening immunity against the usually harmless bugs.
Professor Ian Jones, a virologist at the University of Reading, told MailOnline one possible explanation for a recent rise in severity of enterovirus cases could be mothers not being exposed to common bugs during lockdown.
‘Neonates are protected by maternal antibodies for the first three months of life so I guess one could speculate that lower enterovirus infections due to lockdowns have led to less protective antibody being passed to the new-born,’ he said.
He noted however, that there was currently no evidence of this.
Professor Jones added another factor to consider is that because enteroviruses are such a large group of viruses it is easy for them to recombine and spawn new variants.
‘The current cases in France appear to be caused by such a recombinant, not a previously circulating virus,’ he said.
But he added: ‘While the cases are notable the absolute numbers are small, and I don’t think they signify a general threat.’
Dr Simon Clarke, an infectious disease expert at Reading, said that the cases in France and UK, while caused by same broad group of pathogens, are unrelated.
‘The two WHO alerts are caused by different enteroviruses in babies in different countries, so they aren’t linked,’ he said.
He added that given how people can be infected with enteroviruses unknowingly it may be useful for medics to screen pregnant women for a potential infection.
‘Given as they can be carried without causing disease, the message here is that it might be beneficial to screen pregnant women for the presence of certain pathogens that could cause a serious infection in a newborn,’ he said,
Even if an infection can’t be cured, screening may flag up potential problems before they occur.’