This past weekend I, and most of my horse-owning friends and neighbors, received notification from a local veterinarian's office that West Nile has been conclusively diagnosed in our county. Needless to say, we are concerned.
According to the American Association of Equine Practitioners (AAEP), the first case of West Nile was diagnosed in the U.S. in 1999. In the last 7 years, it has become a leading consideration whenever horses present with neurologic disease. It is, unfortunately, associated with a high mortality rate (over 33 percent of all infected horses die).
West Nile is a flavivirus. Mosquitoes and other bloodsucking insects transmit it to warmblooded hosts like horses, birds, and people. Horses and humans, you may know, are considered "end hosts," which means that the West Nile virus cannot be transmitted from them to another host.
Our West Nile notification suggested vaccinating and boosting existing vaccinations. The AAEP guidelines for West Nile vaccinating recommend that all horses in North America routinely receive the vaccine (though it is not recommended for pregnant mares, and has been associated with foal deformities and death).
Symptoms of West Nile include muscle weakness, stumbling, tripping, twitching, depression, fever, convulsions, partial paralysis, coma, and death. West Nile can be easily confused with other conditions, such as EPM and rabies, that may have similar symptoms.
All told, West Nile isn't really anything to mess around with. The fact that a confirmed case is in our immediate area doesn't exactly fill me with warm fuzzies. Though we've had some cold weather recently, it hasn't been enough to eliminate the mosquitos yet. It looks like we'll be vaccinating again -- sooner than we'd planned...