What pig producers need to know about Senecavirus A

Senecavirus A, or Seneca valley Virus, is appearing in the United States and around the world, and while it is not particularly virulent, it can cause serious headaches due to its similarity to Foot and Mouth Disease.

Seneca Valley Virus, or Senecavirus A, is cropping up at hog farms around the United States. While the virus itself doesn’t appear to seriously impact animal health, the disease’s clinical symptoms are identical to foot-and-mouth disease (FMD), a potentially devastating livestock disease, that is foreign to livestock in the United States.

While the disease appeared sporadically around the U.S. since the late 1980s, it’s never occurred often enough to merit serious attention. Now, the disease is present in 10 U.S. states and more than 150 cases have been reported since July 2015, according to veterinarians studying the disease. The disease's presence underscores the importance of biosecurity throughout the pork supply chain.

In an interview, Dr. Chris Rademacher, a senior clinician and swine extension veterinarian at Iowa State University, said the largest concern is the disease’s similarity to FMD. It is in the same viral family as FMD and it causes similar symptoms, primarily lesions on hoofs, mouths and snouts.

Because of this, state and federal animal health officials are urging hog farmers to be aware of the diseases’ presence, maintain good biosecurity practices, and report any clinical signs of the disease to local veterinary authorities immediately.

“It’s really more of an annoyance or a nuisance than an economically important disease,” Rademacher said. “The fear is we don’t want to … treat every case of vesicles, as, ‘Oh, that’s just Senecavirus; we don’t have to worry about it.’ Then we allow foot-and-mouth disease to come in and it wouldn’t be recognized right away, allowing it to spread rapidly across the United States.”

Appearance and symptoms

Dr. Kelly Lager, a research leader at the U.S. Department of Agriculture’s National Animal Disease Center, spoke about Seneca Valley at Animal Health in the Heartland, a July 20 event held in Omaha, Nebraska, centered on biotech’s role in emergency preparedness. He said the disease flared up in the Midwest in the spring and now between 150 and 175 cases have been reported.

He, and Rademacher, said the disease manifests as vesicles, or fluid filled cysts, on the snout, mouth and hoofs of swine. Typically, the disease manifests near finishing time – when the pig is almost ready for harvest – and lasts seven to 10 days. It causes some lameness in the animals but does not appear to be very harmful and does not affect the marketability of the animal. Lager and Rademacher said the disease can lead to higher than normal mortality in neonatal piglets less than a week old. Transmission and viral shedding, usually occurs within two to three weeks of infection.

Rademacher said it’s unclear how exactly Senecavirus A became more prevalent in the U.S, but it’s possible the virus changed in some way to make transmission easier. The disease also doesn’t always manifest in vesicles and could be carried by animals for a period of time before clinical signs are shown.

Seneca Valley cases were reported in Minnesota, Iowa, South Dakota, Nebraska, Missouri, Oklahoma, Illinois, Indiana, North Carolina and Kentucky. Internationally, Canada, Australia, Italy, New Zealand and most recently Brazil confirmed cases of Seneca Valley virus.

Current effects on the swine industry

The disease is not economically significant, Rademacher said, but it is similar to FMD, which necessitates a swift and thorough response. FMD, an infectious and sometimes fatal viral disease would have serious trade impacts and will damage any nation’s farming economy.

At Animal Health in the Heartland, Iowa State Veterinarian Dr. David Schmitt said farmers that do have the disease and the processing facilities receiving those animals will deal with challenges. Because of the similarity to FMD, a veterinary investigation of the farm or the processing plant is disruptive to the flow of business. Due to the disease’s tendency to appear in animals near finishing, there is a risk the disease can be spread through transportation of animals for processing. Movement is stopped while investigations are underway and ripple effects are felt along the supply chain, he said.

If there is any positive to the disease, Schmidt said, is that it created a better line of communication between state and federal veterinary officials. The potential for disruption underscores the importance of monitoring for the disease, keeping diseased animals off transport trucks, and maintaining high biosecurity standards, Rademacher said.

The future of Senecavirus

Rademacher and Lager said because of the relatively small scale of the disease and its minimal impact on the economics of animal agriculture, its unlikely much more will be done to combat the disease. Funding is limited to study the disease, and drug makers will have little incentive to develop treatments to the disease.

Right now, the efforts to identify the disease and quarantine farms and facilities where it’s been found is working to control the spread of the disease. Continued vigilance should keep Senecavirus A contained.

Austin Alonzo is a reporter at WATT Global Media