Reoccurrence of West Nile Virus Disease in Humans and Successive Entomological Investigation in Sardinia, Italy, 2017

West Nile Virus (WNV) has been endemic to Sardinia region since 2014. Numerous cases of WNV infections were reported in Sardinia in 2011, which had already been on alert since 2008 because of the situation in the rest of Italy. In addition to cases involving wild birds and equidae, four human cases were reported, all of which were lethal. In July 2017, a new case of Neuroinvasive West Nile Virus Disease (WNVD) was diagnosed in a human patient by the detections of WNV antibodies in the patient's cerebrospinal fluid (CSF) and blood. Following confirmation of WNV-positivity, the Istituto Zooprofilattico Sperimentale (IZS) surveyed mosquitoes near the patient's residence by placing traps according to recommendations from the Italian entomological surveillance program. One pool of mosquitoes tested positive for WNV, making this the first case of detection of WNV in a patient's residence.