Available online 24 March 2023, 105425

The rates of enterovirus-associated meningitis increased in late 2021, and then waned during the SARS-CoV-2 omicron wave.

After SARS-CoV-2 omicron decreased, the incidence of enterovirus-associated meningitis rose again.

Echovirus 6 was the leading virus detected in samples of hospitalized meningitis patients before and after the 2021-22 omicron wave

Outbreaks of enteroviral meningitis occur periodically and may lead to hospitalization and severe disease.

To analyze and describe the meningitis outbreak in patients hospitalized in Israel in 2021-2022, during the COVID-19 pandemic.

In December 2021, before the emergence of the SARS-CoV-2 omicron variant, an off-season increase in enterovirus (EV) infections was observed among patients hospitalized with meningitis. In January 2022, enterovirus cases decreased by 66% in parallel with the peak of the Omicron wave, and then increased rapidly by 78% in March (compared with February) after a decline in Omicron cases. Sequencing of the enterovirus-positive samples showed a dominance of echovirus 6 (E-6) (29%) before and after the Omicron wave. Phylogenetic analysis found that all 29 samples were very similar and all clustered in the E-6 C1 subtype. The main E-6 symptoms observed were fever and headache, along with vomiting and neck stiffness. The median patient age was 25 years, with a broad range (0-60 years).

An upsurge in enterovirus cases was observed after the decline of the SARS-CoV-2 omicron wave. The dominant subtype was E-6, which was present prior to the emergence of the omicron variant, but increased rapidly only after the omicron wave decline. We hypothesize that the omicron wave delayed the rise in E-6-associated meningitis.

Enterovirus

Meningitis

Echovirus-6

COVID-19

Omicron variant

© 2023 Elsevier B.V. All rights reserved.