Since January, over 60 positive accessions of the Seneca Valley Virus (Senecavirus A.) have been reported by labs across the United States and new cases appear to be showing up more rapidly as the summer goes on. “This clearly shows that this disease is far from gone,” explains Swine Health Informational Center executive Paul Sundberg. It is unknown if each accession is a new case or a continuation of an existing case. Getting more and timely information will help with analysis.
Sundberg calls for action and collaboration in the industry, “Complacency, apathy, or neglect could result in terrible consequences for the U.S. pork industry. Specifically, it is critical to report all cases of vesicular lesions, suspect coronary banding, and interdigital lesions to state or federal animal health officials.”
The biggest concern regarding SVV is that when clinical signs are present, they are indistinguishable from those of swine vesicular disease (SVD), vesicular stomatitis virus (VSV), and foot-and-mouth disease virus (FMDV.) SVV does belong to the same family as FMDV, and both of these viruses can exhibit erosions, ulcerations, vesicular lesions of the snout, in the mouth, and in the interdigital space between the toes or around the top of the hoof. Lameness could be the presenting clinical sign for SVV, but fever, lethargy, and anorexia may also be present. In some cases, SVV is identified by lifting the leg to carefully examine the space between the toes to look for these lesions.
SHIC Funded Research Helps Industry Decide What Actions to Take
The Swine Health Information Center has funded about $270,000 in research related to SVV post emergence. This research is reported in detail at https://www.swinehealth.org/results/
One result of this research is finding variation of clinical signs among affected herds. According to a study by Dr. Derald Holtkamp and team from Iowa State University, signs observed in piglets ranged from lethargy and ill thrift to increased pre-weaning mortality and diarrhea. In sows, clinical signs ranged from the more traditional snout and foot lesions to lameness and anorexia. In addition, Holtkamp’s research reported that “common suspected risk factors for affected farms evaluated were related to entry of non-on-farm employees, carcass disposal, cull sow removal and entry of breeding replacements.”
According to SHIC funded research by Dr. Sagar Goyal, professor at the University of Minnesota College of Veterinary Medicine, disinfectant studies have shown that 5% household bleach at the 1:20 dilution may be the most effective disinfectant against SVV working best at 15 minutes of contact time. Synergize also worked, but needed 60 minutes of contact time. Notably, Tektrol was not effective in this study.
Additional research was completed on shedding to help guide practitioner decisions. Iowa State University Swine Extension Veterinarian and Senior Clinician Dr. Chris Rademacher reports, “We could detect the genetic material out to 42 days in low levels in tonsils and feces, but we could only detect infectious virus out to 14-21 days in a small percentage of the animals. This most likely means that infectious Senecavirus is probably only shed for 2-3 weeks after an outbreak.”
Regarding elimination, practitioners like Dr. Laura Bruner from Swine Vet Center and others have reported moderate control success with feedback and farm closure techniques. But as Dr. Bruner says, “Opening the farm to gilt replacements will be the true test and we’ll have more knowledge regarding the success of our applied strategies after that occurs.”
SHIC supported webinars on targeted research have provided a means to share information regarding what has worked and where we still need more information. Listen to these webinars online at https://www.swinehealth.org/seneca-valley-virus-summary/