Haematopoietic necrosis virus [cyprinid herpesvirus 2 (CyHV-2)] was isolated during disease outbreaks in goldfish, Carassius auratus, at an ornamental fish retail site in southern England in 2004. Signs of disease included lethargy and inappetence and were first seen after water temperatures increased from 14-15 to 19-21 degrees C. External gross pathology included pale patches on the gills and skin and internally the spleen was enlarged, often with distinctive white nodules. The most prominent histopathological changes observed were necrotic lesions in the spleen and kidney and focal patches of necrosis in the gill lamellae. Necrotic cells often contained nuclei with marginated chromatin and pale intranuclear inclusions. Ultrastructural examination of the spleen tissue revealed typical herpesvirus-like particles measuring 100 nm in diameter. The virus was isolated from extracts of gill tissue in KF-1 cells at 20 degrees C and oligonucleotide primer sets were designed based on conserved gene sequences and used to amplify viral DNA by polymerase chain reaction (PCR). The PCR assays were then used to detect the virus in DNA extracted from tissues sampled during earlier disease investigations at the retail site owner's holding facility in 2002 and 2003 and stored at -70 degrees C since then. Polymerase gene-specific PCR amplification products obtained from tissue samples and from the virus isolated in cell culture shared 100% nucleotide sequence identity with the published sequence for CyHV-2.

Ranaviruses are an emerging group of viruses and have been implicated in an increase of epidemics in susceptible species. They have a wide host range, infecting fish, amphibians and reptiles, with some isolates able to infect multiple species from different animal classes. Whilst some information exists on the pathogenicity of ranaviruses to novel hosts, there is none on the pathogenicity of fish ranaviruses to amphibians; this information is needed to develop measures to prevent the further spread of ranaviral disease in the aquatic environment. We undertook bath infection trials to assess the susceptibility of the European common frog Rana temporaria to 9 ranavirus isolates comprising doctor fish virus (DFV), European sheatfish virus (ESV), epizootic haematopoietic necrosis virus (EHNV), guppy virus 6 (GV6), pike-perch iridovirus (PPIV) and short-finned eel ranavirus (SERV) from fish hosts, and Bohle iridovirus (BIV), frog virus 3 (FV3) and Rana esculenta virus 282/I02 (REV) from amphibians. Animals were challenged as tadpoles at 15 and 20°C and as recent metamorphs at room temperature (20 ± 1°C) to investigate the effect of temperature and amphibian developmental stage on virus pathogenicity. Tadpoles were susceptible to FV3, PPIV and REV, but refractory to the other ranaviruses. Post-metamorphs were susceptible to FV3 and REV but refractory to BIV (the other ranaviruses were not tested). Significant mortality occurred in post-metamorphs and in tadpoles challenged at 20°C but was low in tadpoles challenged at 15°C. This study presents the first evidence of mortality in an amphibian species after challenge with ranavirus originally isolated from fish.

We describe an outbreak of seafood-associated Vibrio parahaemolyticus in Galicia, Spain in on 18th of August 2012 affecting 100 of the 114 passengers travelling on a food banquet cruise boat. Epidemiological information from 65 people was available from follow-on interviews, of which 51 cases showed symptoms of illness. The food items identified through the questionnaires as the most probable source of the infections was shrimp. This product was unique in showing a statistically significant and the highest OR with a value of 7.59 (1.52–37.71). All the nine strains isolated from stool samples were identified as V. parahaemolyticus, seven were positive for both virulence markers tdh and trh, a single strain was positive for trh only and the remaining strain tested negative for both trh and tdh. This is the largest foodborne Vibrio outbreak reported in Europe linked to domestically processed seafood. Moreover, this is the first instance of strains possessing both tdh+ and trh+ being implicated in an outbreak in Europe and that a combination of strains represent several pathogenicity groups and belonging to different genetic variants were isolated from a single outbreak. Clinical isolates were associated with a novel genetic variant of V. parahaemolyticus never detected before in Europe. Further analyses demonstrated that the outbreak isolates showed indistinguishable genetic profiles with hyper-virulent strains from the Pacific Northwest, USA, suggesting a recent transcontinental spread of these strains.

Aquatic animal diseases are a major constraint for increasing aquaculture production. Understanding the contribution of pathogen spread from infected aquaculture sites is critical in devising control measures in the event of an outbreak. We have reviewed the available literature on the persistence in the aquatic environment of several important viral pathogens of fish and crustaceans. These include infectious haematopoietic necrosis virus, viral haemorrhagic septicaemia virus, infectious salmon anaemia virus, koi herpes virus, epizootic haematopoietic necrosis virus and infectious pancreatic necrosis virus, white spot syndrome virus (WSSV), Taura syndrome virus and yellow head virus. Some trends were common to all viruses: (i) viability declined with increasing temperature (at temperatures above 0°C); (ii) higher biological loading in water correlated with reduction in detectable viable viruses; and (iii) virus decay in water is a function of time. Most aquatic animal viruses (AAVs) remained viable for several days or weeks. WSSV is particularly stable. Comparison of studies investigating survival parameters was sometimes difficult because of the different methods employed and different ways in which the data were presented. Data gaps are identified and experimental methods employed for testing critically assessed. The information presented in this review is directly relevant to design effective control measures for AAVs and to explore measures that reduce the economic impact of disease caused by these important pathogens.

Gram-positive cocci recovered from diseased rainbow trout from a farm in England were characterized by different methods, including pulsed field gel electrophoresis, as virulent Lactococcus garvieae serogroup 2 (pulsotype A1). Groups of rainbow trout were kept at a range of temperatures and injected intraperitoneally (i.p.) with one of the UK isolates, L. garvieae 00021. The 18 degrees C and 16 degrees C groups showed 67% and 28% mortality, respectively, by day 27 post-injection. Fish kept at 14 degrees C or lower were less susceptible (< or =3% mortality). Raising the temperature of all groups to 18 degrees C at day 27 post-injection did not result in recurrence of the disease, even though viable bacteria were recovered from all groups 42 days later. Grayling were highly susceptible, with 65% mortalities when challenged with 200 colony forming unit fish(-1) by i.p. injection and 37% mortalities when exposed to effluent water from tanks containing affected rainbow trout. Other fish species tested, Atlantic salmon, brown trout and seven cyprinid species, were less susceptible. Viable L. garvieae was isolated from the internal organs of all species tested at the end of the trials, suggesting that they may pose a threat as possible carriers to susceptible farmed and wild fish.