Vesicular Stomatitis (VS) is a zoonotic disease, caused by the vesicular stomatitis virus (VSV), a member of the Rhabdoviridae family and Vesiculovirus genus. There are two distinct types of VSV that are recognized: New Jersey (NJ) and Indiana (IND). Within the IND, there are three associated subtypes that are classified as IND-1 (classical form), IND-2 (cocal virus), and IND-3 (alagoas virus).
VS mainly affects horses, cattle and pigs. It less frequently is a problem for sheep and goats. It occurs in animals living in the Western hemisphere and occurs frequently throughout South America, Central America, Mexico, and the Southwestern United States. In the United States, VS was first reported in 1916. Since then, outbreaks have occurred in horses and cattle living in New Jersey, New Mexico, Colorado, Utah, Texas, Arizona, Wyoming, Idaho, Montana and Nebraska.
Clinical Signs of Vesicular Stomatitis
Usually the first clinical sign observed in horses with VS is excessive salivation. Distinctive clinical signs associated with VS include the development of lesions along the upper surface of the tongue surface of the lips, corners of the mouth, gums, around the muzzle and nostrils. On rare occasions, horses may develop coronitis in the coronary band area, along with swelling and inflammation. Lesions are usually raised, blanched and occasionally fluid-filled vesicles. If vesicles occur, they are not apparent for very long, and will quickly rupture, leaving ulcerations and erosions. VS was named after the development of the classic associated signs of 'vesicular' and ulcerative lesions. Affected horses usually fully recover after a few days up to 2 weeks.
How Vesicular Stomatitis is Transmitted
VSV is considered to be an arbovirus, as insect vectors are the primary mode of transmission. It is transmitted by numerous different species of insects, including sandflies, mosquitoes, deerflies, horseflies, biting midges, houseflies, eye gnats, black flies, and stable flies. There is also speculation that the VS virus is a plant virus found in pasture grasses. Being an arbovirus, outbreaks of VS usually occur during peak insect growth seasons, which starts in late spring or early summer and continues through to late fall.
Incubation Period for Vesicular Stomatitis
The incubation period for VSV varies from 1-3 days.