Aeromonas salmonicida a potential pathogen in modern eel (Anguilla anguilla) farming?

A fish farm producing turbot suffered from serious and persistent disease o utbreaks caused by A. salmonicida subsp. salmonicida. The farm wanted to st art an intensive production of eels, too, but were concerned about the pote ntial risk of infections with A. salmonicida subsp. salmonicida. Our labora tory carried out a series of pathogenicity tests on eels to evaluate the ri sk. By immersion of eels in bacterial suspensions with densities up to 1.1x 10(10) c.f.u./ml, no mortality was induced and no clinical or pathological changes were found. By injection of the bacteria i.p. or i.m. mortalities w ere re corded but only at high doses of bacteria. Thus, LD50 values of 7.4x 10(7) and 5.0x10(8) c.f.u. were calculated for the i.p. and the i.m. routes , respectively. We therefore conclude that although eels were susceptible t o high doses of A. salmonicida subsp. salmonicida, the risk of infections i n an eel farm must be considered to be minimal under normal circumstances.