KHV

A recent chat with a friend has caused a bit of concern. While chatting to him abouthis recent fishing trip(locally) he said that he had witnessed the owner/leaseholder of the venue netting dead fish from the margins and taking them away in a wheelbarrow. He enquired as to why the fish were dead/dying and was told that it was due to lack of oxygen. It has transpired that in fact, the fish have got KHV and that the EA had been informed.DEFRA has subsequently slapped a Designated Area Order on the venueprohibiting the movement of fish.What concerns me is that the venue is still open for business.Surely the EAshould have closed the venue or do they not have the power?

I do not know much about the disease myself......can it be treated.

My local club has posted notices on its waters alerting thier members to the risk from this water.

Copied the following from the National Association of Fisheries & Angling Consultatives Fact Sheet (issued free to all members)Information Sheet 02/06 February 2006

Koi Herpes Virus

Koi Herpes Virus (KHV) is an extremely infectious viral disease affecting carp (Cyprinuscarpio) in its ornamental and wild varieties. These include:

• Koi carp

• Common carp

• Mirror carp

• Ghost cap• Other variants

At this time there are no reported incidents of other species being susceptible.

Are our UK stocks at risk?

The answer is unfortunately that they are as the virus has been found in the UK on several sites on a number of occasions. KHV is spreading at an alarming pace around the worldsince originally being reported in Israel in the 1990’s, however the disease was actually characterised in ex-Israeli koi carp in the USA in 1998.

It was first located in koi dealers stocks in the UK in 2000 (CEFAS, 2005). KHV is nowpresent in most western European countries. The disease is also widespread in Asiacausing very large mortalities in carp for human consumption. Up to four out of five fishoften die in severe infections. KHV has been identified in UK wild stocks in large-scalemortalities in each of the past three years. However the spread of the disease does notappear to be out or control in the same way that we have seen other non-native parasiticdiseases spread within the UK for example.

2003 – 6 fisheries

2004 – 4 fisheries

2005 – 4 fisheries

The above figures should not be taken as a sign that the disease is not a very seriousthreat with the potential to cause significant mortalities to our wild stocks.

What is being done to protect our fish?

Well there have been some very positive steps. The English Carp Heritage Organisation(ECHO) has funded a researcher at CEFAS to carry out a project looking into the disease,whilst CEFAS have started a surveillance programme of coarse and ornamental farms inEngland and Wales for antibodies to KHV and also further research into: -

• Assessment of the impact of KHV on wild and fishery carp populations in the UK.

• Improved methods to detect sub-clinical KHV.

• Identification of genetic markers to differentiate strains of KHV.

NAFAC Information Sheet 02/06 Koi Herpes Virus. © Page 2

How can outbreaks of KHV be identified in wild stock of carp?

The disease has a number of characteristics such as: -

• Extensive necrosis of the gills.

• Small white focal lesions that eventually spread to all gill arches.

• Tissue sloughs from gill.

• Secondary bacterial and fungal infections.

• Sunken eyes sometimes observed in koi.

• Lethargic, moving into the shallows• Excessive mucus production.

However these symptoms are similar to several other diseases of carp.

How can we protect our stock from KHV?

The best way is to avoid stocking. Where stocking is essential then ask your supplier to have the fish tested for the virus. A fish that has had the disease will have developed antibodies and CEFAS are able to carry out a test for these KHV antibodies. A fish that has the antibodies will have the potential to transmit the disease.

There are two tests currently available from CEFAS. The first is used to detect the virus where a clinical infection exists and is referred to as the PCR test. The second is used to detect the virus when there is no evidence to suspect that the disease is present.

A leaflet ‘New Tests for Koi Herpes Virus (KHV)’ is available from CEFAS. Telephone01305 206600 or www.info@cefastechnology.co.uk.

Are vaccinated fish safe?

Because the vaccine used is ‘live’ and the vaccine displays symptoms of latency manyscientist prescribe to the theory that a vaccinated fish may well have the ability to transmit the disease to naïve fish. It is the author’s belief that no trust should be placed in this as a safeguard until more research is carried out and the results published.

Note: Our Honorary Scientific Advisor, Ash Girdler, prepared this Information Sheet. If further information on this or any other subject is required he can be contacted through theNAFAC web site.

John H (C.S.G.)?

I thank you for your 'low down' on KHV, it is most informative and quite comprehesive, however it has not answered my question. Should the venue concerned be shut, and does the EA have power to shut it down.?

The venue should be shut down. But the E.A. can only advise.

If you have any concerns then contact the EA and have a chat. They will soon act if they are informed of such and they will also let you know how they stand on your question.

If what you say is right then its a poor example of an owner who has little care on welfare issues. Sad really but I'm not surprised.

Another case of profit over sense./forum/smilies/surprised_smiley.gif

No the venue does not need to close to anglers. It should introduce disinfectant net dips and anglers fishing there should ensure that their nets are dried out in the sun afterwards.

KHV is still something of a mystery. I suspect scientists feel it is most at risk of being transferred during the stage when clinical symptoms are evident.