Char-Koosta News
The Official Publication of the Flathead Nation online
July
9, 2008
Cultivating Knowledge on the Flathead ReservationVaccination reduces potential for West Nile Virus in horses
Cases of WNV in horses are down 80-plus percent from peak highs as equine owners learn to combat the disease, and animal health officials are encouraging horse owners to vaccinate their animals against the mosquito-borne disease. West Nile Virus is a preventable disease. According to the Montana Department of Livestock the use of a vaccine or the combination of a vaccine and measures to control the vector significantly reduces the risk of contracting the disease. WNV was first found in the U.S. on the east coast in 1999. Since then, the disease has spread steadily westward, arriving in Montana in 2002. The disease has broad distribution in Montana, having been found in 34 counties. Seven cases of WNV in horses were reported in Montana last year. Those numbers are down dramatically from the previous two years, when Montana had 36 (second most in the nation) and 24 cases, respectively. Nationally, the number of reported cases fell 84 percent in just two years, from 1,086 reported cases in 2006 to 178 in 2008. During the past seven years, 94 percent of Montana’s reported equine WNV cases involved unvaccinated horses. Clinical signs of the disease in horses include loss of appetite and depression, weakness or paralysis of hind limbs, muzzle twitching, impaired vision, loss of coordination, head pressing, aimless wandering, convulsions, inability to swallow, hyper-excitability and coma. WNV mimics other serious neurological diseases like sleeping sickness, equine encephalitis and rabies, and should be immediately reported so that a licensed veterinarian can make a diagnosis. There is no specific treatment for WNV in horses, although supportive care consistent with standard veterinary practice for animals with a viral infection is recommended. Full recovery from the disease is likely, although roughly 30 percent of infected horses will die or be euthanized. Because WNV generally begins to appear at this time of year, it is not too late to vaccinate or get that booster! The vaccine for WNV in horses was first introduced six years ago, with three currently approved for equine use. Vaccination does not guarantee protection against infection, and horses vaccinated against eastern equine encephalitis, western equine encephalitis and Venezuelan equine encephalitis are not protected against WNV. Horse owners should consult with their veterinarian to determine which vaccine best suits their needs. Effective mosquito control also helps decrease the potential for spreading the disease. Watering troughs should be cleaned regularly, and standing water where mosquitoes breed should be managed if possible. A variety of water treatment solutions that kill fly and mosquito larvae but are nontoxic to animals are commercially available. For information on controlling mosquitoes to protect livestock, contact Greg Johnson, veterinary entomology for the Department of Animal and Range Sciences at Montana State University (406) 994-3875; gdj@montana.edu). For more information on mosquito control contact you local Flathead Reservation Extension Office at (406) 675-2700, ext. 1247 or send an email to flatheadreservation@montana.edu. WNV has not yet been found in Montana this year. West Nile Virus is a reportable disease. Any confirmed or suspected case should be immediately reported to the Montana state veterinarian at (406) 444-2043 and/or USDA-APHIS Veterinary Services (406) 449-2220. More information about WNV in horses can be found at:
Additional information about human health aspects of WNV can be found on the Centers for Disease Control web site at http://www.cdc.gov/ncidod/dvbid/westnile/index.htm, and the Montana Department of Human Health & Public Services web site at http://www.dphhs.mt.gov/PHSD/epidemiology/ |
