A meningoencephalitis outbreak associated with echovirus type 18 (E18) in south-western Hungary in mid-2023.

Echovirus type 18 (E18) is a member of the genus Enterovirus of the family Picornaviridae. In this study, we investigated the characteristics of E18 infections in hospitalized adults with meningoencephalitis that occurred during an unusual epidemic in south-western Hungary in mid-2023. Five (6.1%) out of 82 cerebrospinal fluid specimens that were tested were positive for an enterovirus, four of which were E18 (OR372160 and PP861087-PP861090). Headache (100%), fever (75%), retrobulbar pain (50%), nausea (50%), joint/limb pain (50%), exanthema, photophobia, and vomiting were the most common symptoms. Sequence analysis showed that these viruses were related to unpublished emerging E18 strains from France (2022/2023) and China (2019/2020). Further study is necessary to monitor the circulation of epidemic/pandemic E18 variants over time.