Veterinarians and producers in western states should be on the lookout for signs of vesicular stomatitis (VS), which has been reported on premises in Arizona, Colorado, New Mexico, Texas and Utah so far this summer. VS is a reportable disease and positive identification results in quarantine of the affected premises until the disease clears.

So far this year, a total of 25 premises have been confirmed with VS and another 29 suspected.

Last summer, a total of 435 VS-positive premises were confirmed in four U.S. states including Arizona Colorado, Nebraska and Texas.

The virus is spread primarily by insect vectors, and thus tends to disappear during the winter in temperate climates and break out during the summer, particularly in areas where wet conditions encourage insect populations.

Vesicular stomatitis virus (VSV) is classified as a rhabdovirus, and there are two serotypes,  New Jersey and Indiana. Outbreaks this year have involved the New Jersey serotype. Infection with one serotype is not cross-protective for the second serotype. Clinical signs of VS, which can affect equines, cattle, bison, sheep, goats, pigs and camelids include vesicles, erosions, and sloughing of the skin on the muzzle, tongue, teats and above the hooves.

Insect vectors are the primary source of transmission of VS although mechanical transmission occurs in some species. Fly control is a key component in preventing spread of the virus.

Rarely, VS can affect humans, typically those who are in contact with infected animals. In humans the disease typically causes flu-like symptoms. 

 According to USDA’s Animal and Plant Health Inspection Service (APHIS), when a definite diagnosis is made on a farm, veterinarians and producers should take the following steps:

·         Separate animals with lesions from healthy animals, preferably by stabling. Animals on pastures tend to be affected more frequently with this disease.

·         As a precautionary measure, do not move animals from premises affected by vesicular stomatitis until at least 21 days after lesions in the last affected animal have healed.

·         Implement on-farm insect control programs that include the elimination or reduction of insect breeding areas and the use of insecticide sprays or insecticide-treated eartags on animals.

·         Use personal protective measures when handling affected animals to avoid human exposure to this disease.

APHIS offers weekly VS updates and information on the disease on its vesicular stomatitis website