Susceptibility of whirling disease (WD) resistance and WD susceptible strains of rainbow trout Oncorhynchus mykiss to Tetracapsuloides bryosalmonae, Yersinia ruckeri and viral haemorrhagic septicaemia virus

Infections were confirmed by observation of clinical signs, histology and PCR, for all the pathogens investigated. For ERM, an additional bacteriological examination was carried out and for VHS; viral infection was confirmed by cell culture. At least one of these methods confirmed infection in all fish that died following challenges. The German strain H was found to have similar susceptibility as that of the American strain TL to all three pathogens investigated; there were no significant differences in the course of the diseases, clinical signs or mortality.