Immunoglobulin M seropositivity for Toscana virus in a random population sample in Sicily

Objectives: High Toscana virus (TOSV) antibody seropositivity rates have been documented in the last decade, especially in the Mediterranean area. It is unclear if these rates are associated with a recent or past exposure to the virus. This is of importance, as primary infection can cause neurologic complications, especially in adults. The aim of the present study was to assess the current active TOSV circulation in western Sicily. Methods: A cross-sectional seroprevalence study was conducted on 271 individuals aged 4-92 years, sampled from the general population of a small city. Each participant completed a self-administered questionnaire and provided serum, which was analyzed for the presence of specific anti-TOSV IgM and IgG. Results: Anti-TOSV IgM was detected in eight (3.0%) participants, of whom only three had anti-TOSV IgG. The prevalence of anti-TOSV IgM was highest in subjects aged 25-34 and 35-44 years (7.1% and 4.8%, respectively). All subjects positive for anti-TOSV IgM were resident in the suburban area. Conclusions: The detection of IgM documented the circulation of TOSV, a Phlebovirus, in a random population sample of Sicilian adults. The highest risk of TOSV seroconversion in subjects living in the suburbs appears to suggest a high density of TOSV vectors in peri-urban areas.