EN
Streptococcal infections in fish cause high economic losses in the fish farming industry. The species responsible for the streptococcal infection are Lactococcus garvieae, Lactococcus piscium, Streptococcus iniae, Streptococcus agalactiae, Streptococcus parauberis, Streptococcus dysgalactie, Vagococcus salmoninarum and Carnobacterium piscicola. The main pathogenic species are L. garvieae and S. iniae. In some countries, also in European ones, in the summer season these two species cause more than 50% mortality in the rainbow trout industry. Lactococcosis is rapidly spreading throughout the southern part of Europe. Vaccination can be an effective procedure in the control of lactococcosis. The immunity after injection indicates a good level of protection but of short duration. Some of the species of Streptococcus pathogenic for fish are zoonotic agents. Of primary importance is Streptococcus iniae which can cause bacteremic cellulitis and osteomyelitis in humans.