Histopathology of atypical <em>Aeromonas salmonicida</em> infection in Atlantic cod, <em>Gadus morhua</em> L.

The histopathology of an atypical Aeromonas salmonicida found in Atlantic cod, Gadus morhua L., is described. Unlike members of the Salmonidae, the cod showed a well-developed host reaction to A. salmonicida involving encystment of the bacteria. When Atlantic salmon, Salmo salar L., were given an intra-muscular injection with suspensions of cultures of this strain of A. salmonicida no cellular host reaction was observed. When cod were given a similar injection the bacteria showed degenerative changes, leucocytes accumulated, and cyst formation was seen in the spleen and kidney. Since cod can be infected by this organism the possibility exists that they could act as carriers, a source of infection for salmonids in saltwater cage culture or in the wild. [ABSTRACT FROM AUTHOR]