The World Health Organization (WHO) is currently investigating an unusual rise in severe myocarditis cases among newborns and infants in the United Kingdom.

"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 WHO reported.

Myocarditis is a heart inflammation commonly caused by viral infections, including those caused by enteroviruses. Dr. Shamez Ladhani, a consultant pediatrician at the U.K. Health Security Agency (UKHSA) explained that enteroviruses, commonly seen as childhood infections, often result in hand, foot and mouth disease or viral meningitis.

According to the report, 15 newborns and infants presented symptoms consistent with neonatal sepsis between June 2022 and March 2023 in South Wales (10 cases) and Southwest England (five cases). Of these cases, eight required intensive care treatment and one died before being transferred to tertiary care.

In all cases alive at presentation, myocarditis was a presenting feature. The peak incidence of cases was in November 2022 with five. Interestingly, only one similar case has been identified over the previous six years in the South Wales region.