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The genus Edwardsiella is composed of a diverse group of facultative anaerobic, gram-negative bacteria that can produce disease in a wide variety of hosts, including birds, reptiles, mammals, and fish. Our report describes the isolation and identification of Edwardsiella piscicida associated with chronic mortality events in 2 separate captive largemouth bass (Micropterus salmoides) populations in New York and Florida. Wet-mount biopsies of skin mucus, gill, kidney, and spleen from several affected largemouth bass contained significant numbers of motile bacteria. Histologic examination revealed multifocal areas of necrosis scattered throughout the heart, liver, anterior kidney, posterior kidney, and spleen. Many of the necrotic foci were encapsulated or replaced by discrete granulomas and associated with colonies of gram-negative bacteria. Initial phenotypic and matrix-assisted laser desorption ionization–time of flight mass spectrometric analysis against existing spectral databases of recovered isolates identified these bacteria as Edwardsiella tarda. Subsequent molecular analysis using repetitive sequence mediated and species-specific PCR, as well as 16S rRNA, rpoB, and gyrB sequences, classified these isolates as E. piscicida. As a newly designated taxon, E. piscicida should be considered as a differential for multiorgan necrosis and granulomas in largemouth bass. [ABSTRACT FROM AUTHOR]

Avian and fish botulism outbreaks have been recorded since 1999 in eastern Lake Erie. These outbreaks are caused by Clostridium botulinum type E, a toxin-producing bacteria that is found in anoxic substrates rich in organic material. We studied the environmental conditions present in eastern Lake Erie during 2002, a year when several botulism outbreaks were observed. We also tested for the presence of C. botulinum type E in lake sediments. Samples were taken at six stations from two sites of different depths in the Dunkirk (New York, USA) area. The depth of the sampling sites influenced physico-chemical and biological processes in the sediments. We used the quantitative polymerase chain reaction (Q-PCR) to quantify the levels of C. botulinum type E in the samples. Sediment samples contained a patchy distribution of type E spore concentrations (from not detectable to 5520 DNA copies/mg). Samples of benthic invertebrates tested positive for C. botulinum type E spores in tissues ( Gammarus 2028 DNA copies/mg, oligochaetes 428 DNA copies/mg, chironomids 148 DNA copies/mg and dreissenid mussels 715 DNA copies/mg). Principal components analysis (PCA) from inshore stations indicated that a decrease in dissolved oxygen, pH and redox potential near the sediment was associated to an increase in specific conductance and the type E toxin gene in sediments. We also found that C. botulinum type E spores are present in sediments at different depths and at different times through the ice-free season. [ABSTRACT FROM AUTHOR]

No studies exist that address the health risks to humans resulting from environmental exposure to formaldehyde used to treat fish diseases. This study monitored formaldehyde exposure during two treatment scenarios to better ascertain the health risk. When a single 110-L tank was treated as an indefinite bath treatment at 250 mg/L formaldehyde, mean short-term exposure limit (STEL) averaged 0.76 ± 0.73 mg/L and permissible exposure limit (PEL) was 0.152 ± 0.10 mg/L, 10 cm from the source. One meter from the source, mean STEL and PEL were 0.45 ± 0.35 mg/L and 0.070 mg/ L ± 0.013 mg/L, respectively. The second scenario involved a 530-L flow-through tank treated at 250 mg/L as a 1-h flow-through treatment. Mean STEL averaged 1.61 ± 0.344 mg/L and mean PEL averaged 0.14 ± 0.012 mg/L, 10 cm from the source. One meter from the source, mean STEL and PEL were 0.97 ± 0.744 mg/L and 0.172 ± 0.0495 mg/L, respectively. For both scenarios, STEL and PEL were below the recommended exposure limits set by the U.S. Department of Labor, Occupational Safety and Health Administration (OSHA). However, factors such as water temperature, room air exchange rates, and the number of tanks treated per area must be considered when evaluating human health risk. [ABSTRACT FROM AUTHOR]