West Nile Virus Hits Horses; 11 Die So Far
The West Nile virus has begun to infect and kill significant numbers of horses in Southern California, especially in communities in Riverside and San Bernardino counties along the swampy, mosquito-infested Santa Ana River, state officials said.
“We have 26 cases this year to date, all in Riverside and San Bernardino counties,” said Steve Lyle, spokesman for the California Department of Food and Agriculture. “Eleven of those horses have perished. It’s very unfortunate.”
For the record:
12:00 a.m. July 22, 2004 For The Record
Los Angeles Times Thursday July 22, 2004 Home Edition Main News Part A Page 2 National Desk 1 inches; 52 words Type of Material: Correction
West Nile virus -- A photo caption accompanying an article in Monday’s California section on horses dying of West Nile virus stated that vaccine shots cost about $100. A single shot costs about $25, but the total cost to vaccinate a horse is about $100, with two shots and two veterinarian visits.
The disease appears to be spreading rapidly, with 16 of the 26 cases confirmed last week, Lyle said. There was only one case of equine West Nile virus all of last year in California.
Horses cannot infect humans or other horses. When horses become infected, very few exhibit signs of clinical illness. Of those that do, about 30% die or must be destroyed, and another 17% suffer long-term debilitation. Mosquitoes transmit the disease, officials said.
Horses are the domestic animal most susceptible to contracting West Nile virus, and California has 1 million horses -- the second-largest equine population in the United States, officials said.
Dr. Gary Cash, a longtime Riverside County veterinarian, said he has treated seven cases since June 23 and has had to euthanize four of the animals.
“We’re seeing all types: quarter horses, Arabians, young horses and old,” he said.
State officials and veterinarians urged owners to have their horses vaccinated, noting that the two-shot series takes between five to eight weeks to become effective.
“West Nile virus vaccinations for horses have never been more important,” said California State Veterinarian Dr. Richard Breitmeyer. “If people get the necessary booster shots for their horses now, or even just start the vaccination series, horses that may otherwise die can still be protected this season.”
Signs of West Nile virus include stumbling, staggering, wobbling, weakness, muscle twitching or inability to stand. Not every horse exposed to the virus will develop symptoms.
Experts said some owners may have received misinformation about the severity of the disease and the cost, risks and effectiveness of the vaccine.
Isolated cases of pregnant mares spontaneously aborting have been reported after vaccination. While there is always a chance of complications, there is far greater risk to a horse that is not inoculated, some veterinarians said. For about $100, it is possible to save the animal’s life with vaccinations.
In addition to vaccination, horses should be sprayed regularly with insect repellent, and nearby standing water should be removed or treated for mosquito larvae, state officials said.
Human West Nile virus cases climbed to 28 as of Friday afternoon, with no reported deaths, according to the California Department of Health Services. There have been 18 confirmed cases in San Bernardino County, seven in Los Angeles County and three in Riverside County.
Less than 1% of humans infected suffer serious consequences. No vaccine is available for humans.
Horse owners can obtain more information on the website www.cdfa.ca.gov, by clicking on the “Current Issues” section.
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