Isolation and identification of trout viruses in South Africa.

A total of 3,257 samples of diseased rainbow trout were examined for the presence of viruses from January 1983 to December 1987. A virus closely related to the VR 299 serotype of infectious pancreatic necrosis virus was isolated from 13 cases. An additional 7,228 viscera samples from asymptomatic fish were collected during the same period and a similar virus was isolated from 2 sites. During the same period 2,892 ovarian fluid samples were collected and a similar virus was isolated from 1 site. A similar virus was also isolated from one consignment of imported trout ova. A total of 5,550 ova was examined during this period. The viruses were identified by various tests as being closely related to the VR299 serotype of infectious pancreatic necrosis virus. All these samples tested negative for infectious haematopoietic necrosis virus, viral haemorrhagic septicaemia virus and herpesvirus salmonis.