Pathophysiology: West Nile virus (WNV) is a neurotropic flavivirus that has emerged globally as a significant cause of viral encephalitis. Infection of humans is associated with a febrile illness that can progress to lethal encephalitis with symptoms including cognitive dysfunction and flaccid paralysis. Seroprevalence studies suggest that while the majority of WNV infections are asymptomatic, approximately 20 to 30% of infected individuals develop flu-like clinical manifestations characterized as WNV fever.
In 2012, most human cases of WNV infection occurred in north-eastern Italy, in areas that had been affected also in 2010 and 2011. However, in 2012, a markedly higher incidence of WNV infection was observed than in previous years, with 25 cases of WNND, 17 cases of WNF, 14 WNV RNA-positive blood donors, and further two cases of asymptomatic WNV infection identified by active surveillance of subjects at risk of WNV exposure.
The diagnosis of West Nile virus infection is confirmed with a blood or cerebrospinal fluid test. There is no specific treatment for West Nile virus infection. Intensive supportive therapy is directed toward the complications of brain infections. Anti-inflammatory medications, intravenous fluids, and intensive medical monitoring may be required in severe cases.
To face the risk of a new WNV epidemic in 2013, Regional Health Departments, in collaboration with Local Public Health Departments, have planned strengthened public health interventions with enhanced active surveillance and vector mosquito control plans in affected municipalities and with more diffused and detailed information to the general population on how WNV infection is acquired and on the use personal protective practices.