Serological evidence of tick-borne encephalitis virus in limousin, france

Ticks transmit multiple pathogens, including B. burgdorferi, the agent of Lyme disease, and tick-borne encephalitis virus (TBEV), which can cause severe neurological disease and death despite frequent pauci- or asymptomatic infections. The Limousin region is considered at risk for TBEV because of dense tick (Ixodes) populations, although no clinical TBE cases have yet been reported there.

This study assessed TBEV seroprevalence in 880 patients tested for Lyme disease at Limoges University Hospital between January 2020 and January 2023. Presence of neutralizing antibodies was confirmed with a microneutralization assay. Seropositive TBEV cases were asked about epidemiological data.

Anti-TBEV IgG antibodies were detected in 2.61% (23/880) of sera. Three cases had high titers of neutralizing antibodies. For two of them, travel history or missing epidemiological data limited interpretation, but one case from Corrèze department, exhibited an exposure history and lab testing data that strongly support TBEV infection.

For the first time, this study enabled the identification of several factors supporting the hypothesis of the circulation of TBEV in the Limousin region, France, confirming the spread of TBEV from the east to the west of the country and the need for increasing TBEV surveillance.