Persistence of West Nile Virus circulation in North-East region of India: A prospective facility-based study spanning over a decade

To understand the distribution and presence of West Nile (WN) among the acute encephalitis syndrome (AES) patients, a prospective facility-based study was conducted over 13 years (2007-2019). During the period, 8957 patients hospitalized with AES in northeastern India were tested for the evidence of WN virus infection by IgM ELISA followed by Plaque reduction neutralization test (PRNT). Of the samples tested 324 (3.62%) were found positive for WN IgM antibodies and 73 paired sera showed a fourfold rise in neutralizing antibody titre by PRNT. The study establishes WN as a noteworthy cause of encephalitis in an erstwhile endemic area for Japanese encephalitis (JE). Therefore, it is important that WN is recognized as an important acute encephalitis syndrome (AES) causing aetiology in this region and the National centre for vector borne disease control (NCVBDC) guidelines for detection of AES may be modified accordingly. Thus, inclusion of WN in routine diagnosis, along with establishment of an integrative surveillance network with one-health approach will be important.