Confirmation of Senecavirus A cases at a pair of Iowa pork processing plants should remind producers to remain on the lookout for vesicles, or blisters, on their pigs, according to Chris Rademacher, a senior clinician in veterinary diagnostic and production animal medicine at Iowa State University.
Once a rare virus in U.S. pork production, Senecavirus A, also known as Seneca Valley Virus, causes lesions around the snout, mouth and hooves of an infected pig, but the symptoms are rarely fatal and don't last long. Rademacher said federal inspectors temporarily quarantined the pigs that tested positive at the two plants until the virus had run its course.
Senecavrius does not infect humans and does not make pork unsafe to eat, Rademacher said, but that doesn't mean producers should take the virus lightly. The virus's symptoms match those of foreign vesicular diseases such as foot-and-mouth disease (FMD).
FMD has never been confirmed in the U.S., but a confirmed case on U.S. soil would have major international trade implications. For that reason, it's important for veterinarians to contain and diagnose vesicular diseases as quickly as possible.
"When producers get ready to market animals, we want them to walk the barn and specifically look for vesicles. The blisters may be present even though the animals may not be lame," he said.
Rademacher said producers should immediately stop the movement of pigs and call a veterinarian if they spot vesicles.
Senecavirus was a rare disease in Iowa for decades until last summer when the ISU Veterinary Diagnostic Laboratory began confirming five to 10 cases every week from July through September. Confirmed cases declined over the course of last winter but began rising again starting in July.
Personnel at the ISU Veterinary Diagnostic Lab sequenced the genome ofthe current strain of the virus and compared the results to strains of the virus from previous decades and with a strain that appeared during a 2014 outbreak in Brazil. Rademacher said between 5% and 10% of the current strain differs from the old samples and more closely resembles the Brazilian strain.
Researchers believe that this may be a plausible explanation as to why the virus is now more prevalent than in years past, as the mutations may have allowed the virus to move more freely between herds.