Bacterial white patch disease caused by Bacillus cereus, a new emerging disease in semi-intensive culture of Litopenaeus vannamei

The Litopenaeus vannamei aquaculture industry in India has faced a severe problem with a new type of bacterial disease namely white patch disease (WPD). Day by day the disease causes gradual mortalities and once the severe disease outbreak comes, the farm faces high mortality of more than 70% within 3 to 5 days. The major symptoms are white opaque patches in the carapace, necrosis, whitish blue coloration, loss of appetite and pale white muscles. Infected shrimp subjected Gram staining found that the rod shaped bacteria was the pathogen. Genomic identification also confirmed that the causative pathogen is Bacillus cereus WPD (GenBank No: KF673474.1). Also B. cereus WPD had the ability of having higher virulence factors including hemolytic activity, lipase activity and high mortality to the L. vannamei and Artemia when challenging at the rate of 104 to 108 cfu ml− 1.