Vesicular stomatitis

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

Alternative names: VSVs

Information

The disease is mainly present in South and Central America, occasionally in the US, 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.

 

Symptoms

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. In addition, it rarely affects cattle and horses from the same farm and vice versa. 

 

Causes / Contributing Factors

  • 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 they become infected sucking blood from pigs.
  • The virus can also be spread by direct contact between pigs, especially when the density is high.

 

Diagnosis

  • The vesicular stomatitis is of compulsory notification 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 the foot and mouth disease or the 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 10 to 14 days). Tests used are usually the virus neutralization, complement fixation, and ELISA. In pigs, isolated positive samples would be strongly indicative of active infection. The disadvantage of blood tests and serology, is that it involves a delay of at least two weeks, which is too long. 

 

Control/Prevention

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