Seneca Valley Virus May Be Down But It’s Not Out

Just since January, diagnostic labs from across the country have already reported more than 60 accessions positive for Seneca Valley Virus or Senecavirus A (Figure 1). We don’t know from this data if each accession is a new case or a continuation of testing from an existing case. But this clearly shows that the disease is far from gone and underscores the critical need for all cases of vesicular lesions or suspect coronary band or interdigital lesions to be reported to state or federal animal health officials. Since these vesicular diseases are indistinguishable from FMD, complacency or apathy in reporting is not acceptable and could result in terrible consequences for our domestic swine industry.

Of course, the biggest concern regarding SVV is that when clinical signs are present, they’re indistinguishable from those of swine vesicular disease (SVD), vesicular stomatitis virus (VSV) and foot-and-mouth disease virus (FMDV), all more serious and economically devastating foreign animal diseases (FADs) than SVV. Erosions, ulcerations, and vesicular lesions of the snout, oral mucosa, and distal limbs, especially in the interdigital space and around the coronary band, may be observed. In some cases, lifting the leg to carefully examine the interdigital space has been needed to identify lesions, especially in the early stages of the disease. Lameness may be the presenting clinical sign, as well as more general symptoms of illness such as fever, lethargy, and anorexia.

A full series of webinars reporting on SVV research funded by the Swine Health Information Center and other sources (including length of shedding, effective disinfection, epi investigations and a case study of herd closure to eliminate the virus) and the latest on USDA guidance for investigation and responses are available on the SHIC website, http://www.swinehealth.org. Also on the website are fact sheets on SVV and other Swine Disease Matrix viruses.

Follow Proper Protocols, Know the Plan

The USDA has issued a guidance document, https://www.aasv.org/documents/VSG7406.2_SVA_Guidelines_4516.pdf Recommendations for Swine with Potential Vesicular Disease for its field staff that provides a good description of their plan to properly handle potential FAD investigations where information suggests that SVV may be suspected. This guidance tells those doing the investigations that duplicate samples may be taken when appropriate, sending one to a National Animal Health Laboratory Network Veterinary Diagnostic Lab (NAHLN VDL) and another to the Foreign Animal Disease Diagnostic Laboratory on Plum Island, New York. The federal and state animal health officials may use the clinical presentation and the NAHLN diagnostic test result to make initial decisions about movement of the pigs. The USDA lab on Plum Island, however, is the official lab that can confirm a negative FMD test.

As you know, state animal health officials (SAHOs) are charged with the health and well-being of the animals in their respective states. Some of them have released pigs for movement based on the negative FMD results from the NAHLN VDL, as they wait for confirmation from Plum Island. Others may require the Plum Island confirmation test before they can release the pigs in question. Therefore, it’s good to contact the SAHO of your state to understand their perspectives, abilities and limitations in case you are involved in a future investigation.

And, sporadic cases of pigs or sows with vesicles continue to show up at packing plants. U.S. packing plants must continue to be able to operate normally with the number of pigs and sows being processed every day. Vesicular lesions in pigs or sows ready for marketing should be investigated, and if possible, the lesions should be allowed to resolve before shipping. If that isn’t possible, communication between the packing plant, SAHO and USDA is essential if pigs or sows are to be shipped without significant disruption to the normal operations of both the plant and the producer involved.

The mission of the Swine Health Information Center is to protect and enhance the health of the United States swine herd through coordinated global disease monitoring, targeted research investments that minimize the impact of future disease threats, and analysis of swine health data. For more information, visit http://www.swinehealth.org or contact Dr. Sundberg at psundberg@swinehealth.org.