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Vesicular Exanthema

Background and history

The virus of vesicular exanthema of swine (VES) is different from those causing foot-and-mouth disease (FMD) and swine vesicular disease (SVD) but it produces a disease in pigs that is clinically indistinguishable from FMD and SVD both of which are described in detail on The Pig Site. Unlike FMD it only effects pigs.

The story of VES is unusual. It was first diagnosed in pigs in Southern California in 1932. Because of its close similarity to FMD all the pigs were destroyed. It kept reappearing in California from time to time, the pigs being slaughtered each time. Then in 1952 the virus escaped from California in a train-load of infected pork. Garbage fed pig herds came down with the disease and it spread from them to neighbouring herds until herds in 43 states were affected. It was eventually stamped out in 1956 by a major slaughter policy combined with a ban on feeding uncooked garbage to pigs. It was declared an exotic disease in the USA in 1959

The only cases outside the USA were in slaughter pigs on ship from the USA bound for Hawaii in 1947 and in pigs fed uncooked pork scraps from an American military base in Iceland in 1955.

The source of the virus remained a mystery until 1972 when an essentially similar virus was isolated from San Miguel sea lions. When inoculated experimentally into pigs it caused typical signs of VES.

Clinical signs

  • VES does not affect cattle, sheep, goats or any species other than the pigs and sea mammals. So, unlike FMD, if you keep other livestock they will not be affected.
  • Mortality is low but there may be some deaths in sucking piglets.
  • Salivation.
  • Inappetance.
  • Vesicles around the mouth, nose, tongue and feet.

Diagnosis

This is the same as for suspected FMD and SVD and requires laboratory tests to identify it.

Prevention

  • No vaccines are available.
  • The cooked garbage policy in the USA should prevent its reappearance but it's conceivable that an ignorant or careless person may break the rules.
  • If you farm in California do not feed waste sea food to your pigs. Also, do not allow anyone working in your herd to take sandwiches or other food into the pig buildings. Provide a designated eating place for them away from the pigs. This is a good policy anyway.