The paper describes an illness of one-year rainbow trout fry that was characterized by gastroenteritis and progressively high mortality, but which did not indicate a typical bacterial infection; and a clinical illness of cyprinids that indicated typical acute bacterial septicemia caused by Gram-negative bacteria. These diseases of rainbow trout and cyprinids were caused by the Gram-negative motile bacterium Citrobacter freundii. Cultures of Citrobacter freundii were isolated and identified on the basis of key phenotypic characters and with the aid of the Api 20 E system. Pathohistological examination confirmed inflammatory changes in the intestine of rainbow trout; and inflammatory and necrotic changes in the internal organs of cyprinids. We were able to reproduce the illness by means of artificial infection with a pure culture of Citrobacter freundii. This is the first published report confirming Citrobacter freundii as a cause of fish disease in Serbia
High mortality of 1-year old rainbow trout occurred on a fish farm in the spring season, with clinical symptoms typical for acute septicemia. Histological examination revealed inflammatory changes and necrosis of the internal organs. The causative agent was isolated on RTG-2 and EPC cell lines and identified by serum neutralisation, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence (IFAT) as Rhabdovirus carpio. Experimental infection using the virus isolated from rainbow trout caused disease in carp fry, as well. This is the first case of disease of rainbow trout caused by Rhabdovirus carpio, and the first reported isolation of Rhabdovirus carpio from rainbow trout in Serbia. Also, this is the first successful infection of carp with Rhabdovirus carpio isolated from rainbow trout
An acute contagious viral disease caused by Rhabdovirus carpio, spring viraemia of carp, was described for the first time by Fijan in 1972. Carp is the most important susceptible species in all age categories, although other species of cyprinid fish also contract the disease. As the name suggest, the disease typically appears in spring, when the water temperature increases. The disease is often complicated by the secondary appearance of bacterial and parasitic infections. The clinical symptoms include and presume gathering of infected fish near the sides of the pond, uncoordinated swimming, darkening of body color, pale gills, petechial bleeding (of the skin, eyes, gills, and fin bases), exophthalmus, and the appearance of pseudofecal expulsions from the infected anus. Pathoanatomical examination sometimes reveals only oedematous organ enlargement and intestinal inflammation. A varying degree of haemorrhaging is present in the bladder, internal organs, and fluid-containing cavities. Diagnosis is based on isolation and identification of the virus and ELISA in the laboratory. More than 1664 samples were analyzed in the course of the 10-year investigation (from 1992-2002) from different carp hatchery localities in the Republic of Serbia. Rhabdovirus carpio was isolated and identified at more than a third of the tested fish hatcheries (31,57%) infected with the spring viraemia virus. Although the disease was known earlier, it now represents an urgent problem in many European countries, and has been causing great damage in intensive and semi-intensive carp production in our country during the last few years. Therefore, special attention has been paid to it
In this paper we have demonstrated and described disease affecting one-year-old rainbow trout characterized with gastroenteritis and progressive mortality rate, indicating no typical bacteriological septicemical infection. Gastroenteritis of rainbow trout was isolated with Gramm mobile bacteria Citrobacter freundii. Citrobacter freundii cultures were identified by investigation of key phenotypic traits and biochemical methods - Api 20E system. Pathohistological investigation determined inflammatory changes on intestines. By artificial infection with pure Citrobacter freundii culture we have reproduced this disease. This was the first finding of Citrobacter freundii as inducer of disease affecting rainbow trout in Serbia.
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