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 septlcaemia virus and herpesvirus salmonis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

A selective procedure for the field isolation of pathogenic Streptococcus spp. of rainbow trout (Salmo gairdneri)

A procedure established for the selective isolation of the species of Streptococcus responsible for rainbow trout streptococcosis in South Africa, consisted of the inoculation of samples into nutrient broth which had been supplemented with 100 µg/ml of nalidixic acid, 160 µg/ml of oxolinic acid or 200 µg/ml of sodium azide. After incubation, the sample was plated onto tetrazolium agar on which the rainbow trout pathogenic Streptococcus species grew as a red colony. The colonies were isolated from the tetrazolium agar and identified as rainbow trout pathogenic isolates by biochemical and serological tests. In the laboratory the selective procedure is capable of detecting about 2 bacteria per ml. This procedure was used in the field and biochemically identical Streptococcus species were found in the mud and a freshwater crab from the water source of a site with a history of streptococcosis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201