West Nile creates equine epidemic
By Reggie Ellis
Jim Morris, 81, has been breeding horses since he was 13, but he has never seen anything as deadly as the West Nile Virus.
Morris lives on his family ranch on Cornucopia Road just west of Exeter. The area is somewhat of a horse haven in Tulare County with at least 40 horses being raised between Exeter and Farmersville.
"I am extremely concerned," Morris said. "It moved across the country at such a fast pace and now it's here."
The virus was first discovered in Tulare County on July 22 when the Tulare County Health and Human Services Agency confirmed that a dead scrub jay found in Three Rivers had been infected. The disease was first discovered in the United States in 1999 when crows in New York began dying in large numbers. After hearing of its possible spread to the West Coast, Morris began vaccinating all of his horses in 2001.
The disease is fatal in less than 1 percent of reported human cases. Dogs, cats and cattle are not affected by the virus. Birds are a common carrier of the disease. Since birds are migratory they can carry the disease over large geographic distances. A dead bird is an early sign that the virus is in the area. West Nile virus has been detected in dead birds of at least 138 species. Although birds, particularly crows, jays, and raptors infected with virus can die or become ill, most infected birds survive.
Horses are the animals most affected. According to the California Department of Food and Agriculture, 35-40 percent of horses infected will die from the virus. As of July 1, there have been 30 confirmed cases of horses infected with the virus - 10 in San Bernardino County and 20 in Riverside County. Sixteen of the 30 have died or been euthanized. Horses, like humans, become infected by the bite of infectious mosquitoes. The virus is located in the mosquito’s salivary glands. When mosquitoes bite or "feed" on the horse, the virus is injected into its blood system. The virus then multiplies and may cause illness.
Dr. Doug Anez of Pacific Crest Equine Services, a horse veterinarian clinic in Exeter, said he has been preparing for the West Nile Virus since a vaccine for horses was created in 2001. Anez said 90 percent of his 1,800 clients live in Tulare County.
"This is the most devastating equine disease I've seen in awhile," Anez said.
Anez said an infected horse often shows symptoms of encephalitis, or inflammation of the brain and spinal cord. Most horses are already vaccinated against eastern equine encephalitis (EEE), western equine encephalitis (WEE), and Venezuelan equine encephalitis (VEE). But non of those vaccinations will protect horses against West Nile infection.
There are currently two fully approved West Nile virus vaccines available for horses. Each requires an initial series of at least two vaccinations, followed by periodic "booster" injections. The Center for Equine Health recommends that horse owners keep their horses properly vaccinated at all times against this disease. Anez said horse owners should consult with their personal veterinarian regarding which vaccine is most appropriate for their particular horse and how often they should administer booster vaccinations.
Anez said he has enough of the vaccination for the demand. Pacific Crest Equine Services is located at 411 E. Pine St. in Exeter. For an appointment call 592-4753. Symptoms for horses infected with West Nile virus include a general malaise or partial paralysis.
"It is better to give your vet a call sooner than later," Anez said.
The CDC says there is no reason to destroy a horse just because it has been infected with West Nile virus. Data suggests that many horses recover from the infection. All horses that die or are euthanized due to such illnesses should be submitted by your attending veterinarian for a post-mortem exam to the California Animal Health and Food Safety Laboratory System to rule out any possibility of rabies.
The best way to protect horses from the disease is to avoid their exposure to mosquitoes. Anez suggests blanketing horses during the peak mosquito hours around dawn and dusk. Water tanks or any standing water should be emptied periodically to avoid creating a spawning environment for mosquitoes. Morris suggests putting fish that eat mosquito larvae, such as minnows and goldfish, into water tanks.
Anyone with a mosquito problem should immediately contact the Delta Vector Control District at 732-8606. For more information on the effects of West Nile Virus on livestock, symptoms and vaccines go to http://www.cdfa.ca.gov/ahfss/ah/wnv_info.htm.
Tulare County Health and Human Services urges citizens to take the following precautions: