Detection of white spot virus (WSV) in Litopenaeus vannamei from shrimp aquaculture farms in East Midnapore district, West Bengal (India)

White spot syndrome virus (WSV) infection is one of the most virulent pathogenic and devastating viruses of the cultured penaeid shrimps. It leads to severe disruption and loss of economy every year. The present study was carried out to detect the presence of WSV in Litopenaeus vannamei from cultured farms in East Midnapore district, West Bengal for the first time. Out of 8 shrimp samples from different places two samples of Litopenaeus vannamei were found to be WSV positive from Rasulpur and Basanti areas of the district. The confirmation of WSV was detected through two steps PCR reaction. Conventional diagnosis fails to detect early stages of infection, and are also time consuming and less sensitive. Whereas Nested PCR or 2nd step PCR is a powerful and sensitive diagnostic tool for identification of WSV even at a very early stage (asymptomatic/ carrier stage) of infection. Furthermore histopathological studies of gills revealed the presence of developing and fully developed intranuclear inclusion bodies, muscles showed infiltration of haemocytes, necrosis, inflammation with degeneration and inflammation & extensive necrosis of hepatopancreas and degeneration of tubular lumen; thereby confirming the WSV infection among the Litopenaeus vannamei.