Vesicular stomatitis

Vesicular stomatitis produces a disease clinically indistinguishable from foot-and-mouth disease (FMD) and therefore is of great importance.

Alternative names: VSVs

The disease is mainly present in South and Central America, occasionally in the U.S, and rarely, in the form of epidemics that spread north to Canada and south to Argentina.

Produces a disease clinically indistinguishable from foot-and-mouth disease, swine vesicular exanthema and swine vesicular disease. Horses can be infected with vesicular stomatitis but not with FMD. However, the infection in pigs is usually subclinical.

All ages

• Salivation.
• Blisters.
• Injury in the foot and lameness.
• There may be a reduction in the growth rate.
• High fever.
• Clinical signs are similar to FMD.
• Mortality is usually low and most pigs recover within a week or two.
• In contrast to foot and mouth disease, only a small portion of pigs show vesicles. It rarely affects cattle and horses from the same farm. 

• The virus is spread mechanically by a variety of insects and has been isolated from face flies, black flies, eye flies, sand flies, locusts and mosquitoes.
• It is believed that the dissemination among pigs in the epizootic regions, occurs when insects acquire the virus in their buccal area by feeding on lesions that are left after the blisters burst and mechanically transport the virus to other pigs from the same farm or neighboring farms. It is unlikely that insects become infected by sucking blood from pigs.
• The virus can also be spread by direct contact between pigs, especially when density is high.

• The vesicular stomatitis is of mandatory reporting on most epizootic areas since it is clinically indistinguishable from FMD.
• Requires laboratory diagnosis.
• The best samples are the vesicular fluid, having a high concentration of the virus and/or vesicular tissue (eg, the skin surface that is on the blister) which also contains the virus.
• It is necessary to rule out foot and mouth disease or swine vesicular disease (or in California the swine vesicular exanthema) and identify the vesicular stomatitis virus, which in the case of horses can be made from the vesicular fluid or tissue using ELISA, which gives a rapid response, within a few hours.
• Paired blood samples can be taken (i.e., a sample during the initial phase of the disease and at 10 to 14 days). Virus neutralization, complement fixation, and ELISA are the usual tests used. In pigs, isolated positive samples would be strongly indicative of active infection. The disadvantage of blood tests and serology is that it involves a long delay of at least two weeks to get results.

• Because it can not be clinically distinguished from FMD, authorities must be contacted immediately.
• Vaccination of pigs is banned in several countries, although it is possible to produce an effective attenuated live vaccine or an inactivated vaccine.
• Insect control.