Studies on the occurrence of white tail disease (WTD) caused by MrNV and XSV in hatchery-reared post-larvae of Penaeus indicus and P. monodon

White tail disease (WTD) caused by Macrobrachium rosenbergii nodavirus (MrNV) and extra small viruses (XSV) is a major problem. It is responsible for severe mortality in post-larvae of M. rosenbergii in the hatcheries and nurseries. These viruses have a wide host range including marine shrimp. Recently, WTD has been observed in hatchery reared post-larvae of marine shrimp (Penaeus monodon and P. indicus). Clinical signs observed in these animals were found to be similar to those found in the post-larvae of M. rosenbergii. The infected post-larvae showed positive for MrNV and XSV by RT-PCR. The inoculum prepared from these infected post-larvae caused 100% mortality in the post-larvae of freshwater prawn.