Outbreak of autochthonous West Nile virus infection in Lazio region, Italy, July to August 2025: preliminary investigation
Ilaria Mussetto, Andrea Bongiovanni, Francesca Colavita, Cristina Giambi, M. Sala, Cosmo Del Borgo, Fabrizio Carletti, Maria Teresa Scicluna, Alessandro Zerbetto, Angela Corpolongo, Federico Romiti, Maria Beatrice Valli, Stefania Vaglio, Roberto Giammattei, Paola Scognamiglio, Gabriella De Carli, Alessandro Agresta, Claudio De Liberato, Giuseppe Di Luzio, Florindo Micarelli, Emanuele Nicastri, Andrea Siddu, Valeria Ficarelli, Enrico Girardi, Fabrizio Maggi, Francesco Vairo, the Lazio WNV Outbreak Group
Abstract
In July–18 August 2025, 171 autochthonous cases with West Nile virus (WNV) infection were confirmed in Lazio, Italy: four asymptomatic blood donors, 110 with WNV fever, 57 with neuroinvasive syndrome and nine deaths. WNV lineage 2 was detected in two neuroinvasive cases. Infection with WNV was confirmed in 28 horses, five crows and a Culex pipiens pool. We present the preliminary epidemiological and phylogenetic analysis of the outbreak and the public health measures taken within a One Health approach.