Enteroviruses are found worldwide. In temperate regions such as France, an increase in enterovirus infections is observed every year during the summer and fall, primarily consisting of mild cases of meningitis in hospital settings. This increase can begin as early as May but most often occurs during the summer. The summer peak is usually observed in June/July, with a second, smaller peak occurring in the fall. While most enterovirus infections cause few or no symptoms, some infections can lead to severe complications, depending on age, immune status (humoral immune deficiency), or the type of enterovirus.

Given the current epidemiological context marked by a resurgence of enterovirus infections, Santé publique France, in its report published today on 2023–2024 data, reminds healthcare professionals of the need for vigilance and highlights essential hygiene rules to limit virus transmission.

Toward a resurgence of significant enterovirus circulation this summer

The low circulation of enteroviruses (EV) observed in France since 2020, linked to measures to combat the COVID-19 pandemic, persisted through 2022, with EV infection levels well below the peaks observed between 2016 and 2019. Since 2022, a gradual resurgence in enterovirus circulation has been observed in France. The number of EV infections reached 2,339 cases in 2023, with the scale of the summer outbreak close to that of pre-COVID-19 years (an average of 2,720 cases between 2016 and 2019). The meningitis outbreak, meanwhile, was of a similar magnitude to 2019, with 1,555 cases.

In 2024, the number of EV infection cases reported to the Enterovirus Surveillance Network (RSE) as of June 19, 2024, reflects a resurgence of EV infections, observed as early as spring (peaking in week 17), with a higher number of meningitis cases between weeks 12 and 20 (March 18 to May 19) compared to the same period in 2023—293 cases versus 178 cases).

The number of emergency department visits and hospitalizations for viral meningitis reported by the OSCOUR network appears to have been increasing since spring (in week S12) compared to the same period in 2023, though by week 24, the number of cases had reached a level close to that observed in 2023. This could indicate an expected summer peak in the coming weeks.
Vigilance is therefore still warranted throughout the summer of 2024 in light of any resurgence of EV infections and viral meningitis, particularly among very young children.

What are the recommendations for healthcare professionals?

Given the current circulation of enteroviruses and the possibility of a resurgence of enterovirus infections this summer, particularly among young children, Santé publique France and the National Reference Center for Enteroviruses and Parechoviruses urge healthcare professionals to exercise particular vigilance in cases of severe clinical presentations, especially neurological ones, or in immunocompromised individuals, and in any case of severe neonatal infection where an EV infection should be considered and investigated.

They emphasize the importance of collecting appropriate specimens for EV genome testing (LCQ, blood, nasopharyngeal swabs, stool) in all cases of severe clinical presentation. Accordingly, any neonatal infection or severe neurological condition associated with an EV infection must be reported to the CNR, and specimens must be sent to complete virological investigations (including sequencing).