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 a 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.
National Institute of Virology (NIV), Pune, India and evidence of recent infection with West Nile (WN) virus was detected in 88 cases in 2002. These cases of encephalitis were from Japanese encephalitis (JE) nonendemic areas, like Maharashtra and Rajasthan, as well as from JE endemic areas, like Goa and Orissa. Interestingly, neutralizing antibodies predominantly to WN virus were detected in CSF samples by the 50% cytopathic effect inhibition method; the titers ranged from 5 to 375.
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.
In 2002 National Institute of Virology conducted research on West Nile Virus Infection. In a subpopulation of individuals (approximately 1 in 150), a neuroinvasive disease develops. The clinical features of severe WNV infection vary and include severe headache, ocular manifestations, muscle weakness, cognitive impairment, tremors, and a poliomyelitis-like flaccid paralysis.