On 5 April, the UK National IHR Focal Point informed WHO of an increase in severe myocarditis in neonates associated with enterovirus infection in Wales (UK). Between June 2022 and April 2023, ten hospitalised neonates with a positive PCR for enterovirus were found to have myocarditis. Seven of the ten cases were confirmed to have coxsackievirus B3 or coxsackievirus B4. As of 5 May 2023, one patient remained hospitalised and one patient had died. According to the WHO statement, although enterovirus infections are common in neonates and infants, the reported increase in myocarditis - inflammation of heart muscle tissue - with severe outcome associated with enterovirus infection is unusual.
As every spring, there is an increase in cases of enterovirus viral infections. It has been happening for several years (except during the pandemic, for obvious reasons). Among professionals, we already know that this is the case.
It happens in the UK and in all European countries, and it tends to come at this time of year.
There is no particular alarm, it's just that since the word "myocarditis" exploded with the covid-19 pandemic, everyone seems to be very concerned but it's not an unusual situation.
In Spain we don't have this feeling. Neither I personally, nor the National Centre of Microbiology apparently either.
At La Paz Hospital, in all of 2022 there were five neonates with enterovirus infection, three of whom had myocarditis. In 2023, we have had none.
To know whether the UK cases are many or few, we will have to know how many cases there are in other years, which is not mentioned in the published note.
I think that for the moment we cannot create unnecessary alarms. As they [the WHO statement] say, myocarditis is relatively common in neonatal enterovirus infections. Enterovirus is very common, especially in spring or summer epidemics, and there is a case every year. So far, we have not detected any unusual increase in cases of enterovirus infection.
Senior Researcher, Head of the Enterovirus and Viral Gastroenteritis Unit (Reference and Research Laboratory for Immunopreventable Viral Diseases), Centro Nacional de Microbiología, Instituto de Salud Carlos III
At the moment, I cannot assess whether the figures are alarming or not, but from the data we have at the Enterovirus Reference Laboratory of the National Microbiology Centre and from discussions with other clinicians, it does not appear that there has been an increase in cases of neonates with enterovirus myocarditis in Spain.
Nor do we have news that what has been reported from Wales (UK) is occurring in other European countries. However, the European Network for the Study of Non-polio Enteroviruses (ENPEN) is already collaborating to study this issue properly.
Enteroviruses are very prevalent viruses that circulate every year with an increase in incidence usually in the spring-summer months, mainly affecting children. The co-circulation of the different genotypes (more than 100 different genotypes are known) varies from year to year and, while some circulate every year, others circulate in the form of epidemic outbreaks every 2-3 years. To understand the epidemiology and clinical features associated with infections by the different enterovirus genotypes, longer and more extensive surveillance studies are required to investigate which genotypes are circulating each year and what pathologies they cause, whether there has been a significant increase in the circulation of a particular genotype causing an increase in cases, or whether, within a particular genotype, a more pathogenic strain has emerged that could cause more severe cases.