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Information on KHV and Hazorea Aquatics’ Biosecure Koi Facility

Koi Herpes Virus (KHV) has been active in Koi and carp fish farms in Israel since 1998. It is believed the disease was imported to Israel in broodstock and equipment that came from a defunct Koi breeding farm in the UK. KHV is suspected to have existed before 1998 in East Europe, the US and Japan. Today it has spread to all Koi producing countries. Paradoxically, it was the openness of Israeli producers and authorities and their willingness to share information that fueled rumors that the virus started in Israel, or that Israeli farms were responsible for its propagation. In fact, more research on this disease and on ways to deal with the threat it represents has been done in Israel than in any other country in the world.

Three Methods of Combating the Virus – Only in Israel:

After extensive research and experimentation, Carp and Koi farmers in Israel developed a method for “active immunization" of fish. The “immunization” is achieved by infecting the fish with KHV in a controlled environment, and then putting them through a temperature change. This enables the immune systems of the Carp/Koi to effectively combat the virus and recover completely without any lingering damage or signs of disease. There is little documented evidence to date that fish that have been "immunized" in this way have demonstrated symptoms of KHV again or that they have redeveloped pathogens. However, there is some evidence that a few fish "immunized" in this way may be (or become) carriers of the virus and can even become re-infected and/or transfer the virus to other fish during periods of stress. The long-term effects are still not known, and we also have no way of knowing if this process is effective against mutations of the virus. This method has proved extremely cost effective and efficient for the production of carp for consumption.

 Research at the HebrewUniversity - HadassahMedicalSchool in Jerusalem has led to the production of a vaccine against KHV - produced from the attenuated virus. In 2007, an Israeli company became the first in the world to vaccinate all its exported Koi with the new vaccine. The vaccination is carried out through immersion. However, even the developers of the virus are uncertain regarding the long-term effects of the vaccine, and during 2007 a number of virus outbreaks were reported amongst Koi that had been vaccinated. Many leading experts in the field continue to hold that some of the vaccinated fish are carriers and that the vaccine does not provide a solution for new emerging strains or future possible mutations of the virus. In addition it is feared that the spread of fish vaccinated with attenuated virus will introduce large numbers of virus carriers that will seriously hamper future programs to monitor the presence of the pathogenic virus and make it very difficult to establish disease-free populations of Koi. To date, The European Commission has decided to recommend banning of imports of vaccinated Koi to Europe starting October 2008.

Following the KHV outbreak in 2001, Hazorea Aquatics made a strategic decision not to continue working “with” the virus but to raise virus free Koi. Following trials at a pilot project and a study of a similar site in Europe, Hazorea decided to invest in a new, entirely isolated, completely Biosecure indoor, intensive system that could produce guaranteed KHV free Koi throughout the year in large quantities. To date, this is one of the only completely Biosecure large scale commercial Koi RAS (Recirculating Aquaculture System) facilities in the world.

 
Hazorea Biosecure Koi

The facility contains 8 separate systems for the breeding and initial growth of larvae and fry, and 4 systems for on-growing. The entire facility is completely isolated from the goldfish hatchery, the outdoor ponds and the rest of the farm. It has its own water source and strict measures of disinfection and sterilization are enforced regarding personnel, instrumentation and equipment in order to minimize the possibility of external sources of disease entering the system. Access by staff and visitors is monitored and regulated and birds and rodents cannot enter the facility. The Koi are grown from egg to shipping box in a totally enclosed and biosecure facility.

The system enables Hazorea to market between 1 and 1.5 million disease-free Koi all year round, while minimizing the risk of contamination. The system is not sterile, meaning that the Koi are susceptible to various parasites and bacteria that usually exist in some quantity in all water. It should also be noted that no system can be infallible or hermetically sealed off from all outside influence, but since all the fish in the system are always completely visible and in a controlled environment (as opposed to the fish in outside ponds), staff can respond immediately to any problem and treat it effectively. More importantly, the water temperature in the system is always at the level where KHV is most active. Since KHV cannot be detected in water temperatures below 62ºF, this ensures that KHV cannot go undetected (as it can in facilities shipping out of colder water). At Hazorea any signs of KHV can be spotted quickly and in sufficient time to curtail deliveries to customers. Hazorea Koi are also examined regularly at the Israeli Agricultural Ministry animal health laboratories and at the CEFAS laboratories in the UK. These tests include testing by PCR and ELISSA assays.

At Hazorea we continue to strive to improve the quality of what we supply to our customers. New high quality Brood-stock, have been incorporated especially for the purpose of introducing new bloodlines in the spawning. Some of the new fish were from Hazorea’s own closed system, while others were brought in especially from Japan and kept in a separate quarantine for 12 months before their introduction.

The result has been a rapid increase of demand for Hazorea Biosecure Koi around the world. Customers are reporting a marked increase in quality as well as a noticeable advantage in that Hazorea Biosecure Koi adapt quicker to new surroundings, are less shy, and less prone to stress. Everyone loves Koi that rush to meet each new visitor that approaches their tank.

Too much is still unknown about KHV, and that is why we at Hazorea are sure that the most effective way to successfully combat it is to go “back to basics” and not export fish that may be carrying the virus. Hazorea Koi can never be a source of possible virus contamination.

Koi businesses and keepers around the world have been affected by KHV. In fact, no facility, anywhere, can be completely sure that it will not be the next to be infected unless steps are taken to insure that the Koi are supplied from a virus free source. We at Hazorea Aquatics are confident that our biosecure system will produce healthier, virus-free Koi, thus contributing to our customers’ security and peace of mind.