Lactococcus garvieae and Streptococcus iniae infections in rainbow trout Oncorhynchus mykiss: similar, but different diseases

Clinical and macroscopic findings (anorexia, lethargy, loss of orientation and exophthalmia) indicate that Streptococcus iniae and Lactococcus garviea e infections of trout share some common features, but histopathology reveal s notable differences between the 2 diseases. Meningitis and panophthalmiti s are the main lesions among S, iniae infected trout, whereas L. garvieae i nfection results in a hyperacute systemic disease. Differences in the LD(50 )s of the 2 pathogens and the sudden onset of signs and death correlate wit h the histopathological findings. indicating the severity of L. garvieae in fection of trout.