The Virginia Department of Agriculture and Consumer Services (VDACS) today announced the first diagnosed case of West Nile Virus (WNV) in a horse in 2013. The horse is from Russell County. It had been vaccinated for WNV just two weeks prior to becoming ill. The horse is being treated with supportive therapies to prevent the animal from injuring herself throughout the two to three week cycle of the disease. Often horses have to be euthanized because of the severity of their symptoms, which may include low-grade fever, ataxia (loss of full control of bodily movements), hypermetria (lifting its feet excessively high) and intermittent central nervous system depression.
In April 2013 VDACS sent out an announcement encouraging horse owners to discuss a vaccination schedule for West Nile Virus and Eastern Equine Encephalitis with their veterinarians. Vaccines are available to drastically reduce the incidence of WNV and EEE in horses. The vaccines are effective for six to twelve months, so horses should be re-vaccinated at least annually. In areas where the disease occurs frequently, most veterinarians recommend vaccination every six months.
The WNV vaccine for equines initially requires two doses administered three to six weeks apart. The vaccine takes four to six weeks from the second dose for optimal effectiveness. Horse owners should consult with their veterinarians to choose a re-vaccination schedule to protect their horses effectively. Prevention methods besides vaccination include destroying standing water breeding sites for mosquitoes, use of insect repellents and removing animals from mosquito-infested areas during peak biting times, usually dusk to dawn. Continuous, effective mosquito control can minimize the risk of exposure of both horses and humans to West Nile Virus and other mosquito-borne diseases.
The virus usually lives in wild birds of many different species. Mosquitoes transmit it from bird to bird. Occasionally a mosquito that has bitten an infected bird will then bite a human, horse or other mammal and transmit the virus to them. Transmission between horses and humans is extremely unlikely.
WNV can cause a horse to go down and be unable to get up without help. Animal owners should consult their veterinarians if an animal exhibits any neurological symptoms such as a stumbling gait, facial paralysis, drooping or disinterest in their surroundings. Animal owners should consult their veterinarians or the nearest VDACS Regional Animal Health Laboratory for advice or information should an animal exhibit symptoms of WNV. Click here for contact information at the five regional laboratories.
The following Web sites provide more information on WNV and how to protect humans and horses:
Virginia Department of Health
Two days ago on September 9, VDACS announced the first horse in Virginia to test positive for Eastern Equine Encephalitis.
Update, September 12, 2013
VDACS has just learned that the Russell County horse that was diagnosed with West Nile Virus had recently moved to Virginia from another state and may have been exposed to the virus prior to being moved to Virginia.