Autochthonous West Nile Virus Infection Outbreak in Humans (Asti, Piedmont, Italy, August–October 2018) and Long-Term Sequelae Follow-Up

West Nile virus (WNV) infection is a reemerging zoonosis recently provoking significant outbreaks throughout Europe. During the summer of 2018, the number of WNV infections rose with a peak of new diagnoses of West Nile neuro-invasive disease (WNND). Most of the Italian cases were clustered in the Po River Valley. We present a case series of nine patients with WNV infection admitted to the Cardinal Massaia Hospital from 30 August 2018 to 1 October 2018. Demographic, immunovirological, clinical and therapeutic data are shown, and a report on clinical sequelae from the subsequent follow-up in patients with WNV and WNND. We showed the clinical, radiological and biochemical characteristics of WNV-infected patients. The risk factors and the clinical presentation of WNV in most patients in our case series were typical of that described in the literature, although, despite the high morbidity and mortality of WNND, we showed survival of 100% and long-term sequelae in only three patients. Environmental conditions may be essential in WNV outbreaks, and WNND can be clinically neurological multiform. Our long-lasting follow-up with clinical or radiological monitoring confirmed the morbidity of long-term neurological sequelae after WNND. Further studies are needed to investigate the epidemiology and physiopathology of bacterial superinfections after WNV infection.