Streptococcosis in aquaculture

Streptococcosis caused by the genera Streptococcus and Lactococcus have occurred in cultured freshwater, brackish water and marine fish species owing to the worldwide development of intensive aquaculture. In Japan, four pathogens, Streptococcus iniae, S. parauberis, S. dysgalactiae and Lactococcus garvieae, have been observed in aquaculture. Infections of these pathogens cause high mortality rates in the species important for aquaculture such as yellowtail, red sea bream and flounder. Recently, commercial vaccines have been licensed against these pathogens to prevent the infections in some aquaculture species. This review describes the outlines and topics of the diseases.