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Overview of Vesicular Exanthema of Swine


Vesicular exanthema of swine (VES) is an acute, highly infectious disease characterized by fever and formation of blisters on the snout, oral mucosa, soles of the feet, the coronary band, and between the toes.

Since 1972, a virus indistinguishable from VES virus (VESV), designated as San Miguel seal lion virus (SMSV), has been isolated from throat and rectal swabs from premature and 4-mo-old California sea lion pups, dead and weanling northern fur seal pups, and nursing northern elephant seal pups. It has also been isolated from vesicular lesions on marine mammals, commercial seal meat produced in Alaska, and perch-like fish collected from tidal pools off the southern California coast. SMSV isolated from both fish and marine mammals is capable of producing VES in pigs. In addition, caliciviruses isolated from throat and rectal swabs from dairy calves cause clinical vesicular exanthema in exposed pigs. One calicivirus serotype, SMSV-5, has been recovered from vesicular lesions on the palms and soles of a researcher working with the virus.

VESV, SMSV, and related viruses are members of the genus Vesivirus in the family Caliciviridae. Many immunologically distinct serotypes have been demonstrated (13 types of VESV from pigs and at least 16 types of SMSV from marine sources). Additionally, a number of serotypes have been named after the host species from which they were isolated: bovine, primate, cetacean, walrus, skunk, mink, rabbit, and reptile caliciviruses. In some cases, serotypes initially isolated in terrestrial animals (eg, reptile calicivirus) have subsequently been found in marine mammals. All of these viruses (except for SMSV-8, SMSV-12, and mink calicivirus) form a single virus species, vesicular exanthema of swine virus.

In pigs, the clinical disease is indistinguishable from foot-and-mouth disease (see Foot-and-Mouth Disease), vesicular stomatitis (see Vesicular Stomatitis), and swine vesicular disease (see Swine Vesicular Disease). Originally confined to California, VES became widespread in the USA during the 1950s, but a vigorous campaign to eradicate the disease was successful. In 1959, the USA was declared free of VES, and the disease was designated a foreign animal disease; it has never been reported as a natural infection of pigs in any other part of the world.

Presumptive diagnosis in pigs is based on fever and the presence of typical vesicles, which break within 24–48 hr to form erosions. Diagnosis can be confirmed by ELISA, reverse transcriptase-PCR (including a real-time RT-PCR), complement-fixation tests, and electron microscopy on epithelial tissue, or after passage in swine tissue cultures. Serum neutralization tests and immunoelectron microscopy are also used.

Suspected cases of vesicular exanthema should be reported immediately to the proper authorities. Garbage and fish should be cooked before being fed to pigs.

Last full review/revision March 2012 by Nick J. Knowles, MPhil; David J. Paton, MA, VetMB, PhD, MRCVS

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