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Thread: KHV: Irresponsible People And Ignorance

  1. #21
    Oyagoi yerrag's Avatar
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    Quote Originally Posted by MikeM View Post
    I think I must not understand. It seems you want a study to see if naïve koi can be infected by carriers? Do you doubt that a naïve koi would be infected by a koi shedding the virus?
    I meant the same exact study be done this time on koi that has never been infected with KHV to see if the KHV virus will appear. This way, we can be sure it's not simply the temperature stress that's causing the expression of the KHV virus. The design of the study should involve a control group, which was overlooked.

  2. #22
    Daihonmei MikeM's Avatar
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    The "temperature stress" utilized in the OSU studies involves koi maintained at 12C (54F). Temperature is increased from 12C to 23C (73-74F) at a rate of 1C per day. The temperature is then held constant for 4 days at 23C. Then is lowered back to 12C at a rate of 1C per day. 23C is in the permissive range for KHV. At 12C KHV is inactive. I do not think many would consider 1C per day a stressful temperature change in a colloquial sense. It is a 'stress' in the context of KHV studies because it places the koi in an environment that allows KHV to become active.

    These are low temperatures for those in warm climates, but not unusual for Japan, Europe and much of the U.S. Having water warm by 11C over 11 days would be unusual.

  3. #23
    Oyagoi yerrag's Avatar
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    Thanks for looking up what the temperature stress involved, Mike. As you said, the low temperature range sets the stage for the virus to become active. Given that ponds coming out of winter need to rebalance to adjust to a constantly changing equilibrium, the stress on koi can be significant to make them more vulnerable to viral infection. Koi keepers in warmer clime have it easy.

  4. #24
    Daihonmei MikeM's Avatar
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    I was sent a link to a July 14 UK press release concerning a KHV outbreak. Unlike the U.S., KHV is a reportable disease in the U.K.:



    "Press release

    Koi herpesvirus disease outbreak confirmed in Greater London

    From:Centre for Environment, Fisheries and Aquaculture Science
    First published:14 July 2016

    Koi herpesvirus (KHV) disease has been confirmed in carp (Cyprinus carpio) at Maidenhead aquatics - Wembley

    Carp mortalities from Koi herpesvirus (KHV) disease

    An outbreak of KHV disease has been confirmed at Maidenhead Aquatics – Wembley, The Greenhouse, Chilcot Nursery, Birchen grove, Greater London.
    The site is now subject to statutory controls to prevent the spread of the disease. The Fish Health Inspectorate (FHI) at Cefas, acting on behalf of Defra has issued a confirmed designation prohibiting the movement of fish to, from the effected system onsite.
    KHV has no implications for human health. It is nonetheless, a serious viral disease of fish, and is notifiable in the United Kingdom. KHV affects all varieties of common and ornamental carp (Cyprinus carpio) and can result in high rates of fish mortalities.
    Clinical signs of KHV disease may include white or necrotic patches on the gills, rough patches on the skin, sloughing mucous and sunken eyes. These signs usually appear when water temperatures are between 16 and 28 degrees centigrade. Anyone noting deaths in carp or carp hybrids, with signs of disease similar to those above, or have suspicion of notifiable disease in any aquatic animal, should immediately contact the FHI.
    Anyone who imports, keeps, fishes for, or retails carp (common and ornamental) and carp hybrids should take precautions to prevent the spread of KHV."

    It is still around.

  5. #25
    Daihonmei MikeM's Avatar
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    For those not aware, there have been a number of reports of KHV outbreaks in the southeastern U.S. over the past few weeks. A couple of outlets are suspected, but it is very difficult to pinpoint a source unless the hobbyist has separately quarantined new acquisitions. The possibility of a carrier already being in the pond makes it impossible to be certain.

    I am posting simply as a continuing warning that KHV remains a serious threat. A decade ago, an outbreak in multiple ponds in several states all around the same time would have generated huge volumes of sad stories of the individual hobbyists, much finger pointing, demands for information regarding any rumored source and dire predictions. Nowadays, isolated outbreaks go un-mentioned and this current outbreak has not gotten much notice. People become lax and start thinking KHV somehow went away.

    So, once again... Your own quarantine is the best way to minimize your risk, but every koikeeper should start by acquiring their koi only from known, reputable dealers who acquire their koi from breeders who follow bio-security protocols, who themselves maintain bio-security and who are open in explaining what they do to assure safety. If you do not know, ask.

    And, no matter how good the deal, or how heart-breaking, do not go rescuing koi from some abandoned pond or purchasing off Craig's List... or from some unknown Ebay seller.

  6. #26
    Sansai
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    Am I right in saying you quarantine fish in all good faith,they pass the test. The pond temperatures change and the fish start dying.

    Costia then becomes the culprit.Water parameters first then get the scopes out.

    Did I read very recently the cure for KHV is VIRKON? Really?

    What's the panic?

    I thought there was no cure for KHV.

    Garfield

  7. #27
    Tosai
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    Quote Originally Posted by coolwon View Post
    Am I right in saying you quarantine fish in all good faith,they pass the test. The pond temperatures change and the fish start dying.

    Costia then becomes the culprit.Water parameters first then get the scopes out.

    Did I read very recently the cure for KHV is VIRKON? Really?

    What's the panic?

    I thought there was no cure for KHV.

    Garfield
    My understanding is that Virkon is used to kill the virus in a pond that had fish with KHV in it. In other words it is used to "sterilize" a pond but it does not kill the virus in the host fish.
    IMHO you can do the same thing by simply draining the pond and or use bleach and leave the pond empty for a week or so.

  8. #28
    Daihonmei MikeM's Avatar
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    Quote Originally Posted by coolwon View Post
    Am I right in saying you quarantine fish in all good faith,they pass the test. The pond temperatures change and the fish start dying.

    Costia then becomes the culprit.Water parameters first then get the scopes out.

    Did I read very recently the cure for KHV is VIRKON? Really?

    What's the panic?

    I thought there was no cure for KHV.

    Garfield

    There is no cure for KHV.

    The QT procedure for protecting against KHV is much more extensive than for parasites and bacterial diseases. It requires having the temperature in the permissive range, having a 'victim' koi present to catch the disease in the event the new fish is an asymptomatic carrier and a long duration of months, not weeks. There are detailed protocols published. Since few hobbyists have the facilities to properly quarantine for KHV, in practice the best protection is knowing the source is bio-secure.

  9. #29
    Daihonmei MikeM's Avatar
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    Quote Originally Posted by Douwe View Post
    My understanding is that Virkon is used to kill the virus in a pond that had fish with KHV in it. In other words it is used to "sterilize" a pond but it does not kill the virus in the host fish.
    IMHO you can do the same thing by simply draining the pond and or use bleach and leave the pond empty for a week or so.
    Correct.

    To sterilize existing facilities, bleach can be used in a heavy concentration with all filters, etc. left operating. All non-submerged surfaces are sprayed with bleach. Nets, tubs and other equipment are submerged in bleach water. Although a few hours of concentrated bleach exposure is probably enough, dealers who have had to sterilize have tended to keep it going for an extended period of several days. Then empty everything, let it dry out thoroughly.... and start anew. Be ready for dealing with new pond syndrome. ....Note: Bleach can degrade a liner pond, some plastics, etc.

  10. #30
    Tosai
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    Quote Originally Posted by MikeM View Post
    Correct.

    To sterilize existing facilities, bleach can be used in a heavy concentration with all filters, etc. left operating. All non-submerged surfaces are sprayed with bleach. Nets, tubs and other equipment are submerged in bleach water. Although a few hours of concentrated bleach exposure is probably enough, dealers who have had to sterilize have tended to keep it going for an extended period of several days. Then empty everything, let it dry out thoroughly.... and start anew. Be ready for dealing with new pond syndrome. ....Note: Bleach can degrade a liner pond, some plastics, etc.
    Excellent point. Bleach is nasty stuff and needs to be used with a great degree of caution.

    Back to the KHV thing and your point about using trusted sources for fish: I could not agree more. Currently I use only two dealers and both only buy and sell high quality fish that they personally source from only trusted Japanese Koi Farms (they go to JP frequently and source in person). Both the dealers and farms stand to lose hundreds of thousands of dollars in inventory as well as their reputation and lively hood if they try to cut corners. The reputable farms are all doing random blood sampling and ELISA testing to statistically determine if they have KHV in their farm. The dealers quarantine the fish after they arrive from Japan for a minimum of 3 to 4 weeks.

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