Experimental Streptococcus iniae infection in barramundi (Lates calcarifer) cultured in Vietnam

Document Type: Primary Research paper

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Abstract

Streptococcus iniae has become one of the most important fish pathogens. This work describes first isolation of this bacterial species from cultured barramundi in Khanh Hoa, Vietnam. Three Streptococcus iniae strains (Aum, C4 and CR3) were tested for virulence in barramundi model using intraperitoneal injection at concentrations of 102-107cell per ml. The results showed that the LD50 of Aum, C4 and CR3 when the barramundi were challenged via intraperitoneal were determined to be 104.8, 105.6 and 105.8 CFU respectively. Moribund barramundi diplayed similar clinical symtoms, i.e., erratic swimming, haemorrhage at base of fins, tail rot. Fifteen days after challenge, S. iniae could not be isolated from kidney, spleen, liver or brain of surviving fish. 

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