Viral haemorrhagic septicaemia update - virus detected in grayling sample

The discovery was made through comprehensive sampling. Cefas is continuing to test wild fish in the river, both below and above the infected farm to determine the extent of infection.

Although there is no scientific evidence that VHS infection causes significant disease outbreaks in wild freshwater fish stocks, any persisting infection in wild stocks could be a source of infection or re-infection for trout farms in the vicinity through VHS virus contamination of the river supply to the farms.

There have been no further cases of the disease on trout farms in the Ouse/Don catchments of North Yorkshire affected by the current case. The first round of testing on all farmed sites has returned negative results so far and is due to be completed later this week. A second round of testing began last week with results expected by the middle of July.

Results of the further testing will be made known when they have been completed. Fish farmers in the affected area and other stakeholders are being kept informed of the situation.

VHS has no implications for human health.

Notes to editors

The sample was confirmed positive by the CEFAS National Control Centre on 19th June.

On the 22nd May, Fish Health Inspectors from the Centre for Environment Fisheries and Aquaculture Science (Cefas), acting on behalf of Defra, inspected a trout farm in Yorkshire following a report from the farm manager of high levels of mortality in the farm stock. Samples were taken and analysed at the Cefas Weymouth laboratory, and the presence of Viral Haemorrhagic Septicaemia (VHS) has been confirmed. VHS is a notifiable disease which affects mainly farmed rainbow trout, and can cause significant mortality.

This is the first outbreak of VHS recorded in mainland Great Britain, although there was an outbreak of the marine form of the disease in farmed turbot in the Isle of Gigha in 1994.

The Diseases of Fish (Designated Areas) (England)(No.2) Order 2006 restricts the movement of any live fish or live eggs of fish into or out of the designated area and farms without the prior written consent of Defra.

The designated area is now defined as:

• the geographical area from which water drains to form the Yorkshire River Ouse catchment to its Estuarial Water Limit at Boothe Ferry Bridge, National Grid Reference SE7333 2625; and
• the geographical area from which water drains to form the River Don catchment to its Estuarial Water Limit at Goole, National Grid Reference SE7495 2288.

Further information on VHS and other serious freshwater diseases can be found on the Defra website and in its “Combating Fish Disease” publication. Our sister site, www.efishbusiness.co.uk also provides information on fish health matters.

To organise a fish health inspection on suspicion of an outbreak, contact the CEFAS Fish Health Inspectorate on 01305 206673/74

or by sending an email to: fish.health.inspectorate@cefas.co.uk

This Designated Area Order (DAO) came into force on 7th June 2006.

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