These reports have been primarily in New Mexico, Colorado and Arizona. The disease appears to be spreading, however, and several states have restricted import-transport of horses from several Western states. In addition, horses that arrive in Kentucky must have a blood test to identify animals that may have been exposed to the virus. So far vesicular stomatitis has been limited to the western hemisphere. It primarily affects cattle, horses and swine.
Vesicular stomatitis is zoonotic, meaning that humans are susceptible to the virus as well.
The disease typically occurs in the United States from late spring through early fall. Outbreaks of vesicular stomatitis generally occur at about 10-year intervals, although favorable climatic conditions can bring on more outbreaks. How vesicular stomatitis spreads is not completely known. Insect vectors, mechanical transmission and movement of animals may play a role. Once the disease is in a herd, it moves from animal to animal by contact and exposure to saliva.