KHV – It Can Happen in Your Pond

Published on November 2, 2012

cavoy_koi_pond_tancho_kohaku Over the past few months, officials have confirmed that Koi Herpes Virus (KHV) caused the death of numerous koi and carp in the US. Several KHV outbreaks have been reported in California, New York, Texas and Missouri resulting in devastating losses for koi hobbyists.

The economic impact of KHV can be extreme. Based on the replacement value of koi stocks alone, it’s estimated that the impact of KHV has already exceeded $120 million in the US.1 Given mortality rates in excess of 70% and the unpredictability of outbreaks, koi worth more than $3 billion are at risk every year. To date, roughly 15% of koi dealers have experienced a KHV outbreak and 31% of hobbyists have direct or indirect experience with KHV.2 While there is no cure for KHV, there is now a preventative solution called CAVOY®, the first and only vaccine registered in the US to help prevent KHV.
**What You Need to Know About KHV**
KHV is a highly contagious viral disease that infects ornamental koi and common carp. Since the first recognized case was detected in England in 1996, the disease has spread rapidly. In fact, it was declared endemic in Israel in 1998 and is now present in all countries that culture koi, excluding Australia. “KHV is the single most devastating threat to koi ponds and the koi industry as a whole,” said Dr. Nick Saint-Erne, DVM, Technical Services Veterinarian for PetSmart Inc. “With the introduction of Cavoy vaccination, there is now a preventative option available to supplement proper pond management and biosecurity measures to reduce the risk of the disease.”

KHV is also referred to as cyprinid herpes virus type 3 (CyHV-3). It is transmitted through direct contact with infected fish, body fluids from infected fish, through water or contaminated equipment. The virus infects via penetration of the skin, gills and possibly oral consumption.

KHV is diagnosed by virus isolation, antibody testing or PCR (Polymerase Chain Reaction) techniques. Alarmingly, more than 80% of fish exposed to the KHV virus at permissive temperatures will die 7 to 21 days following infection.3 In those koi that survive the initial infection, the virus may stay with the infected fish for the duration of their life, making the exposed fish potential carriers of the virus.

With the commitment and investment of time, effort and costs to set-up a pond, it can be devastating to hobbyists if the new addition of a koi to a pond causes an outbreak in their cherished koi.
**Prevention is the Best Medicine**
There is no cure for KHV, so the best way to protect against it is to take control of the fishes’ environment. As part of a broader KHV control strategy that includes pond management, general sanitation and containment measures, CAVOY is highly effective in helping prevent KHV and keeping koi healthy.
It is also important to consider quarantine procedures as part of your koi-health measures. Quarantining new koi shipments is a must for koi dealers and koi hobbyists alike when the health of the koi is a top priority.

If pond owners are concerned that their koi may have been exposed to KHV, it is recommended that the fish is placed in a quarantine tank, well isolated from the main pond, and only handled with nets and equipment that are dedicated for use in the quarantine tank.

CAVOY is a vaccine, which is why it can only be administered under the supervision of a veterinarian. Unlike most vaccines that are injected, CAVOY is an immersion vaccine. To administer the vaccine, no needles, syringes or sedatives are needed. Koi are simply placed into a clean, aerated tank containing the vaccine for 45 minutes to one hour. Research studies are being conducted to confirm a recommended revaccination schedule.

The vaccine works by triggering the koi’s own natural disease-prevention mechanism, the immune system, to destroy KHV before the disease can take hold. In studies conducted in the US, survivability between 73% and 100% RPS (relative percent survival) against the wild type of the KHV virus was observed. CAVOY is a United States Department of Agriculture (USDA) approved vaccine and has an established safety profile when used according to label directions. In US studies, post vaccination survivability rate in koi weighing more than 100 grams was greater than 99%.

Maintaining a healthy koi pond involves several aquatic specialists – from pond professionals to koi retailers, knowledgeable hobbyists to trained aquatic veterinarians, they all have a role to play in protecting and preserving the beauty, balance and health of a koi pond. To learn more or to locate an aquatic veterinarian near you visit

**Side Bar – Did You Know?**
• Nearly 4.5 million US homes have koi as pets
• On average, nine koi live in each home pond
• Koi live typically 25 to 35 years, but can live 60 years or more
• 31% of koi hobbyists have direct or indirect experience with Koi Herpes Virus (KHV)
• KHV is transmitted readily through water and via contact with infected fish or contaminated equipment
• There are no curative therapies for KHV
• KHV has a mortality rate of >80% and most deaths occur in under 15 days post exposure to the virus
• Survivors of KHV may become disease carriers, intermittently shedding virus without disease symptoms
• CAVOY is the first safe and effective KHV vaccine for koi available in the United States

1 Novartis market research. Data on file.
2 Novartis market research. Data on file.
3 Ronen et al., 2003.

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