Reduction of antibacterial drug use in Norwegian fish farming due to vaccination.

Sales statistics for antibacterial drugs and vaccines intended for use in farmed salmonids in Norway were collected and analysed. In 1993, there was a substantial reduction in annual sales figures for antibacterial drugs, which continued in 1994 and 1995. Oil-adjuvanted vaccines containing antigens against furunculosis were introduced in the fall of 1992. Introduction of oil-adjuvanted vaccines has been the single most important cause for the substantial reduction in use of antibacterial drugs in Norwegian fish farming industry.