USDA is reporting that Vesicular stomatitis-positive premises have been confirmed as of mid-August, 2019, in 6 states: Colorado, Nebraska, New Mexico, Oklahoma, Texas, and Wyoming.
Since the last situation report on August 9, 2019 there have been 117 new VSV-affected premises 36 confirmed positive, 81 suspected premises identified.
The 2019 VSV outbreak began on June 21, 2019, when the National Veterinary Services Laboratories (NVSL) in Ames, Iowa confirmed the first VSV-positive premises in Kinney County, Texas.
New Mexico, Colorado, Wyoming, Oklahoma, and Nebraska subsequently broke with cases which were confirmed by NVSL on June 26, 2019 in Sandoval County, New Mexico, on July 3, 2019, in Weld County, Colorado, on July 24, 2019, in Platte County, Wyoming, on July 29, 2019, in Tillman County, Oklahoma, and August 9, 2019, in Lincoln County, Nebraska.
Since the start of the outbreak, 450 affected premises have been identified. Seven hundred eighty of these premises have only equine species clinically affected.
In Colorado, steps are being taken by the Colorado Horse Park to protect horses after twenty-six cases of Vesicular Stomatitis Virus have been reported in three counties.
Vesicular stomatitis (VS) is a viral blister-forming disease affecting humans and livestock, including horses, cattle, sheep, goats, pigs, llamas, and alpacas. Vesicular stomatitis virus is the only one of the blister-forming viruses to affect horses. A veterinarian diagnosing VS must report the case to the state and federal authorities, and the horse and property will be quarantined to avoid spread of the disease.
The incubation period is 2-8 days. Signs of VS in horses include a fever in the early stages, lethargy, and loss of appetite mainly due to the formation of vesicles, the blister-like sores, that form in the mouth. Vesicles are the primary distinguishing sign of VS and may form on the lips, tongue, gums, muzzle, sheath, teats, vulva, and at the coronary bands.
The vesicles burst after a day or two leaving ulcerative sores. Horses with mouth lesions may avoid food and water and may drool copiously, in fact excess salivation is often one of the first signs noted. Horses with coronary band lesions may become lame, and weight loss is not uncommon.
Vesicular stomatitis may be spread by direct contact from an infected horse to another horse or to a human – via contact with ruptured vesicles. It may also be spread by buckets, feeders, and grooming supplies that contact infectious material from a sick horse.
Vesicular stomatitis tends to occur during the warmer parts of the year especially during fly season and the virus has been isolated from several species of biting flies. It is suspected that insects may transmit the disease from horse to horse.
The disease generally runs its course within two weeks. While it causes significant economic loss and pain/debilitation to the horse, VS is generally not fatal.