Aeromonas Causes Severe Skin Lesions in Rainbow Trout (Oncorhynchus mykiss): Clinical Pathology, Haematology, and Biochemistry

Abstract

Aeromonas infection caused mass death of rainbow trout, Oncorhynchus mykiss (Walbaum) weighing 394 ± 69 g, at a water temperature of 4 o C in April. In a bioassay, the disease was induced by an Aeromonas strain whose biochemical characteristics most closely resembled Aeromonas sobria and Aeromonas caviae. The development of the skin lesions started as depigmented spots surrounded by a hyperaemic zone with the formation of ulcers, or the changes on the skin resembled furunculosis, taking the form of very large prominent bulges filled with clear exudate which, when broken, revealed haemorrhagically altered muscle. Some fish showed exophthalmus; inflammation around pectoral fins; hyperaemia of the wall of the swim-bladder and petechial haemorrhages on the liver were found inside the abdominal cavity. Severe anaemia was characterized by a reduced erythrocyte count and lower haematocrit and haemoglobin levels. Clinical chemistry analyses in the diseased fish indicated reduced levels of total protein, cholesterol, triacylglycerol and total calcium and an increase in the urea level. Among the five enzymes and isoenzymes analyzed, catalytic concentration reaching multiples of the normal level was found in alanine aminotransferase, lactate dehydrogenase, α-hydroxybutyryl dehydrogenase and γ-glutamyl transferase. Electrophoretic analysis indicated a reduced level of albumin in the diseased fish. These results point out the importance of mesophilic motile Aeromonas as causal agents of severe skin affections in salmonids. The findings encourage efforts to extend the knowledge of clinical haematology for the identification of health disorders and specific responses typical of the individual diseases. Aeromonas caviae, Aeromonas sobria, histopathology, red blood count, biochemical indices, blood plasma, electrophoresisThe care of the health of fish stocks in intensive salmonid culture necessitates the participation of qualified veterinary supervision. Among the suite of methods for examination of the physiological health of the fish, an increased awareness of the usefulness of clinical chemistry is materializing among first pathologists and veterinarians. Appropriate haematological and biochemical assays may identify changes in organ function, find anomalies in the metabolism, determine additional laboratory procedures and make prognoses. Synthesis and analysis of the figures obtained for the individual diseases may provide valuable information on the specific response or the range and nature of the pathological process. For salmonids this is confirmed by the analyses performed by

Effects of bacterial infestation caused by human wastes on the skin structures of Mugil platanus Günther, 1880 (Mugilidae)

“…The tissue lesions detected were tegument and caudal peduncle muscles necrosis and they were different in each of the sampling spots. Ours results are similar to the ones described by Rehulka (2002), which verified enormous prominent bulges developed on fish skin and the lesions were filled with clear to slightly turbid exudate, in some cases with a slight tint of blood. On a cut section, they exposed haemorrhagically altered muscle.…”

“…Since diseases caused by bacteria originated from human activity are affecting the juveniles of this species, this can compromise the maintenance of fish stocks in the estuary. Flores-Lopes et al (2001;2002) used the presence of lesions/anomalies in fish species as an instrument of biological evaluation of environmental quality. The results obtained in our study with Mugil platanus specimens, re- assure the importance of using anomalies as indicators of environmental alterations and degradations of anthropic origin which compromise the quality of ecosystems.…”

Haemato-biochemical disorders associated with nodavirus like-agent in adult leaping mullet Liza saliens (Risso, 1810) in the Caspian Sea

“…The same results were seen both in the infectious diseases and in the longtime starvation [20,[33][34][35]37]. The reduction of TP and albumin could be the result of amino acids deficiency and/or reduced proteins synthesis due to hepatopathy and renal failure, however, the reasons are not clear for us.…”

“…Analysis of data obtained for individual diseases may provide valuable information on the specific responses in pathophysiological processes of the disease [2,23,34,35,41,48].…”

Effect of polychlorinated biphenyls (Delor 103) on haematological and enzyme parameters of the rainbow trout Oncorhynchus mykiss

“…In general, a lower Na ). Enzymes are increasingly used not only as indicators of pathological processes (Bell 1968, Racicot et al 1975, Shieh 1978, Harbell et al 1979, Waagbø et al 1988, Ř ehulka 2002b but they also play an important role in toxicology (Lusková et al 2002) and as indicators of stress. LD, creatine-kinase, and the ALT and AST aminotransferases are primarily used for the lastmentioned purpose.…”