Equine Herpes Virus Infects Calif. Horses

On Tuesday, Jan. 24, a horse at the Empire Polo Club in Indio, Calif. was euthanized due to complications from equine herpes virus-1. An additional 16 cases were identified at Rancho Sierra Vista in San Juan Capistrano. Both sites have been placed under quarantine.

The news has horse owners in the Riverside and Orange counties extremely nervous about the health of their horses. Horse shows in the area have been cancelled to avoid transmission of the virus.

Nine equine herpes viruses (EHVs) have been identified to date. EHV-1 is one of the viruses that pose the most serious threats to a horse’s health. Symptoms of EHV-1 include fever, inflammation of blood vessels in spinal cord and brain, muscle weakness, abortion, and neonatal death.

EHVs are actually very common in horses, however, many horses do not show symptoms of the virus. The virus might be latent, or inactive, causing the horse to be an unknowing carrier of the virus. The virus spreads quite easily through direct horse-to-horse contact, in the air, and on fomites (inanimate objects that are capable of carrying living organisms) such as people’s hands, feed and water buckets, grooming equipment, and tack. While humans can transmit the virus from horse to horse, they are not at risk of being infected by the virus. The virus can remain alive outside of a horse’s body between seven and 28 days, depending upon the environmental conditions. Therefore, it is extremely important to clean and disinfect equipment, hands and surface areas when EHV infection is suspected. While there is no vaccine to prevent the neurological form of the herpes virus, there are methods of treatment. It is important to treat an infected horse as soon as possible, as horses have a greater chance of survival if treatment is begun early on.

In May 2011, there was another outbreak of EHV-1 and EHM, or equine herpes myeloencephalopathy, which is the neurological disease associated with the virus. Several horses became infected with EHV after attending a national horse show in Ogden, Utah. After the show, the disease was found in California, Texas, Idaho, New Mexico, Oregon, Arizona and Washington State.


Click here to read HealthMap’s summary of the 2011 outbreak.

Related Posts