Chapter 18 - Red sea bream iridoviral disease

Abstract

Red sea bream iridoviral disease (RSIVD) is an acute and highly contagious disease caused by red sea bream iridovirus and infectious spleen kidney necrosis virus, members of genus Megalocytivirus. RSIVD causes systemic infection in many species of marine and freshwater fishes, in both food and ornamental fishes, and the outbreaks can result in mass mortalities up to 100%. The diseases have been reported in many countries, especially in East and Southeast Asia. The infected fishes usually show symptoms of lethargy, body discoloration, and abdominal distension or ascites. Gross pathological changes of infected fish are enlargement of internal organs, especially spleen. Infection with these viruses produces a characteristic presence of enlarged basophilic cells within infected organs. Increasing biosecurity and good aquaculture management to prevent virus exposure, together with the adoption of rapid and accurate diagnostic techniques combined with vaccination, are the most effective measures to control RSIVD.