Deyan STRATEV, Stoycho STOEV, Ivan VASHIN, Hristo DASKALOV
The main clinical and pathomorphological changes in Aeromonas hydrophila infection in carp provoked by different field strains of this bacterium were studied. The strongest histopathological damages were seen in the functional epithelium of liver and kidneys, followed by intestine and hearth damages in addition to various haemorrhages in interstitial tissues of visceral organs and some skin haemorrhages on the ventral surface of the body and the anal region. As a whole, pathological damages consisted of degenerative changes as cloudy swelling, granular and/or hyaline droplet degeneration or vacuolation in functional epithelium in the respective internal organs in addition to some target vascular disturbances, which appeared to be good biomarkers for field assessment of that disease. Pathological damages in internal organs and haemorrhages were stronger in experimental fishes exposed to higher levels of the respective pathogens, especially those isolated from dead anaconda or the referent strain, and less pronounced damages were seen in fishes infected with of Aeromonas hydrophila isolated from a silver carp with marked signs of septicaemia.