Review of research on streptococcosis in tilapia

Streptococcus spp. is gram-positive and is one of the major bacterial pathogens causing infectious diseases in human as well as in many vertebrates including swine, cattle and fish. Currently, the outbreak and prevalence of streptococcosis in fish,often occurring in various species of marine and freshwater fishes and mostly occurring in fishes of warm watershave already been reported by many countries. There are more and more reports of tilapia infected with streptococcosis in China. In 2009, the outbreaks of streptococcosis were found in tilapia farms in southern China, including Guangdong, Guangxi, Fujian and Hainan provinces; the rates of streptococcal infectivity and mortality were 20%~50% and 50%~70%, respectively. Thus, streptococcosis has seriously hindered thedevelopment of tilapia aquaculture. This review summarized the reports on pathogeny, epidemiology, control and prevention of streptococcosis in tilapia, which would provide references for the prevention and controlof streptococcosis in tilapia in the future.