title: An outbreak of Shewanella putrefaciens group in wild eels Anguilla anguilla L. favoured by hypoxic aquatic environments.
abstract: Microbiological analyses were conducted on wild eels from the L'Albufera Lake (Spain). A total of 174 individuals were collected in two surveys (i.e. year 2008 and autumn-winter 2014) among those caught by local fishermen into the lagoon. The prevalence of Shewanella putrefaciens group was 1.7% in 2008 and rose above 32% in 2014. It was due to an outbreak of shewanellosis that presented a morbidity rate of 64%. S. putrefaciens group strains were isolated as pure cultures from the sick eels that showed white ulcers surrounded by a reddish inflammation, damage of the mouth, extensive skin discoloration, exophthalmia, ascites and bad odour. The S. putrefaciens group was recovered from freshwater samples taken at the L'Albufera system, along autumn-winter 2015. Its counts significantly increased in freshwater parallel to hypoxia and temperature rising. Shewanellae strains were identified as S. putrefaciens and S. xiamenensis by 16S rRNA gene sequencing. These isolates recovered from sick eels or freshwater were virulent for European eel by IP challenge (LD50106CFU g-1body weight). They also caused 30-38% cumulative mortality, in European eels challenged by a 2-h bath (107CFU mL-1). These results suggest that shewanellosis could be transmitted through water highlighting the fact that hypoxic conditions increase this bacterium levels in water.
authors.affiliation: Departamento de Microbiología y Ecología, Universitat de València, Valencia, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Esteve
authors.affiliation: Departamento de Microbiología y Ecología, Universitat de València, Valencia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Merchán
authors.affiliation: Departamento de Microbiología y Ecología, Universitat de València, Valencia, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Alcaide
mesh_terms: D000693:Anaerobiosis; D000811:Anguilla; D000818:Animals; D004196:Disease Outbreaks; D005393:Fish Diseases / Q000453:epidemiology* / Q000382:microbiology; D005618:Fresh Water; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D012621:Seasons; D020614:Shewanella putrefaciens / Q000502:physiology*; D013030:Spain / Q000453:epidemiology
keywords: Shewanella putrefaciens; Shewanella xiamenensis; hypoxic aquatic environments; wild European eels