With more than 3,000 cases of West Nile virus documented in the United States, including in Montana and Wyoming, veterinarians with the Southeast Alaska Veterinary Clinic are recommending horses in Juneau be vaccinated for the virus.
Dr. Barb Deyell, a veterinarian at the clinic, said authorities do not know for certain whether the West Nile virus poses a threat to Southeast Alaska horses.
"The virus is transmitted by migratory birds, and the fear is that a lot of the birds could fly down south for the winter, pick up the virus and bring it back," Deyell said. "What we don't know is if the mosquito life cycle is long enough here for the disease to be transplanted."
The clinic will offer initial doses of the vaccination Saturday at Swampy Acres stable and the Fairweather Equestrian Center. Booster doses will be given Oct. 5, and a second booster will be given next spring before the start of the mosquito season, Deyell said.
Horses become infected with the West Nile virus when bitten by an infectious mosquito. The virus multiplies in the horse's blood system, infects the brain, and interferes with the functioning of the horse's central nervous system. Most horses recover from the infection, but, just as with humans, horses have been killed by the virus.
According to the Web site for the federal Centers for Disease Control, www.cdc.gov, 1,295 people had been infected and 54 people killed by West Nile virus in the United States between Jan. 1 and Sept. 12.
If horses in Alaska are infected with the virus, there is a chance humans will be infected as well, said Dr. Louisa Castrodale, an epidemiologist with the Alaska Department of Health and Social Services.
"Horses and humans are sort of the spillover in terms of what gets infected," Castrodale said. "If you get a mosquito that bites an infected bird and then bites a human or horse, you'll get the disease ... The general feeling is that it's unlikely the virus will get established up here, but the bottom line is that we don't know."
The horse vaccine's effectiveness has not been proved, according to the CDC. The agency said no human vaccine has been developed yet.
The state's epidemiology Web site, www.akepi.org, includes more information about the virus.
Christine Schmid can be reached at firstname.lastname@example.org.