Published: Thu, 6 Mar 2014 11:56:56
By: Steve Knowles
Koi herpes virus KHV causes a highly contagious, usually fatal disease of koi and common carp. Experts consider it to be the single biggest threat to koi ponds and the koi industry as a whole. The first case of disease related to KHV was identified in England in 1996
Koi herpes is so simple that it can’t reproduce on its own but must infect koi cells and “hijack” the cells’ internal workings, effectively turning each cell into a virus-making machine. Now consider how hard it would be to control such a disease. In order to kill the virus, you would also have to kill the cells it has infected, so the cure would likely be as bad as, or even worse than, the disease.
After KHV has infected a cell and reproduced many copies of itself, the newly created viruses rupture the cell and go on to infect other nearby healthy cells within the koi’s body. Because KHV is so effective at reproducing itself and destroying cells, it is a highly effective killer of koi.
A small percentage of fish will survive koi herpes virus (KHV) infection, thanks to the fish’s immune system. But besides these natural defenses, there is no way to cure an infected fish and restore it to koi health. (Unfortunately, even if there were a cure, by the time you can see disease symptoms it would probably be too late to save the fish and the rest of the pond.)
Some research reports indicate that raising the water temperature in a pond for several weeks could help slow and even stop the progression of KHV in some infected koi. But these reports also made two other findings. First, that the fish losses are still high despite the higher-temperature regime. Second that this temperature regime does not remove the virus from the koi's body. The virus is simply inactive and can reactivate later, with the fish becoming sick again. Or, worse, these fish could then act as carriers, spreading KHV to healthy koi.
The best way to prevent KHV is to take control of your fishes’ environment. When buying new animals, be mindful of the supplier and their reputation. Avoid situations where water from unknown sources may contaminate your otherwise clean pond water. (It's no exaggeration to say that even a drop of tainted water can start an outbreak in a pond.) And keep koi healthy by inoculating your koi with CAVOY, the vaccine that prevents KHV.
You should also consider quarantine as part of your koi-health measures. According to the Associated Koi Clubs of America (AKCA), quarantine is a must if you take your koi to koi shows. If you're concerned that your koi may have been exposed to KHV, place it in quarantine tank, well isolated from the main pond, and only handle with nets and equipment that are dedicated for use in the quarantine tank. There is no defined duration of quarantine, but various experts suggest 21 days to a year.
But there is hope. CAVOY is the first and only vaccine registered in the U.S. to prevent KHV. In clinical trials where koi were vaccinated with CAVOY then intentionally infected with KHV, an average of 88% of the koi survived, relative to unvaccinated koi.3
For more info on KHV and Cavoy go to www.cavoy.comDescription: Koi herpes virus KHV causes a highly contagious, usually fatal disease of koi and common carp. Experts consider it to be the single biggest threat to koi pond
Key Words: Koi Herpes, Cavoy,Koi Health, Koi Vaccinations