Phylogenetic Analysis of the 2020 West Nile Virus (WNV) Outbreak in Andalusia (Spain)

Casimiro-Soriguer, Carlos S.; Perez-Florido, Javier; Fernandez-Rueda, Jose L.; Pedrosa-Corral, Irene; Guillot-Sulay, Vicente; Lorusso, Nicola; Martinez-Gonzalez, Luis Javier; Navarro-Marí, Jose M.; Dopazo, Joaquin; Sanbonmatsu-Gámez, Sara

During recent decades West Nile Virus (WNV) outbreaks have continuously occurred in the Mediterranean area. In August 2020 a new WNV outbreak affected 71 people with meningoencephalitis in Andalusia and six more cases were detected in Extremadura (south-west of Spain), causing a total of eight deaths. The whole genomes of four viruses were obtained and phylogenetically analyzed in the context of recent outbreaks. The Andalusian viral samples belonged to lineage 1 and were relatively similar to those of previous outbreaks which occurred in the Mediterranean region. Here we present a detailed analysis of the outbreak, including an extensive phylogenetic study. As part on this effort, we implemented a local Nextstrain server, which has become a constituent piece of regional epidemiological surveillance, wherein forthcoming genomes of environmental samples or, eventually, future outbreaks, will be included.