Infections of Edwardsiella tarda among brook trout in Quebec

Acute bacterial septicemia is commonly diagnosed in brook trout Salvelinus fontinalis of Quebec. Canada. The agents most commonly isolated include Aer omonas salmonicida (furunculosis), Aeromonas hydrophila (motile aeromonad s epticemia), and Pseudomonas species. Septicemia in brook trout caused by th e gram-negative bacterium Edwardsiella tarda was diagnosed for the first ti me in the province of Quebec from two different fish farms producing stock for fee fishing establishments. Affected fish displayed nonspecific lesions associated with bacterial septicemia including hemorrhages on the gills an d viscera and exophthalmia. Stress-associated immunosuppression due to an i ncrease in summer water temperatures and lack of precipitation were conside red as primary causes of these disease outbreaks.