SHIC-Funded Study: Senecavirus A Transmission Risk Lower After 30 Days

A recent study that looked at the duration of Senecavirus A (SVA) shedding from clinically affected and non-affected sows and piglets after a breeding herd infection was completed by Iowa State University and funded by the Swine Health Information Center (SHIC). The principal investigator, Dr. Chris Rademacher, reported that there appears to be a short-term risk to other herds when a sow farm has a SVA outbreak, but that it may be lower 30 days after the outbreak. Summary: The study was designed to evaluate the length of shedding of SVA from a sow farm undergoing a SVA outbreak in the fall of 2015. The main goal was to obtain information regarding the SVA shedding pattern in a sow herd to provide some guidance on how long they should be closed to minimize the risk of transmitting the virus to other herds or to end-point, cull-sow markets.

To evaluate the SVA shedding patterns of sows and piglets, researchers used PCR and virus-isolation methods. Tonsil, rectal swabs, and serum were collected from sows and their piglets for six consecutive weeks. In sows, PCR results indicated that SVA RNA was detected at low levels out to six weeks post-outbreak in tonsil and rectal swabs, while detectable levels of SVA RNA in serum were only observed for three weeks post-outbreak. There was no viable virus isolated from any sow samples. In piglets, PCR results indicated that SVA RNA was detected at low levels (20 to 40 percent positive) out to three weeks post-outbreak in tonsil, rectal swabs, and serum. Viable SVA was found through virus isolation in less than 10 percent of piglets during weeks one and two post-outbreak, but virus isolation was negative by the third week. These findings may suggest that SVA is most likely a short-term risk to other herds and the risk of transmitting Senecavirus A may be lower after 30 days. This report, along with many other SVA resources, may be found at the SHIC website. As always, you may contact Dr. Paul Sundberg, SHIC‘s executive director, for more information about how SHIC is working to bring useful and relevant disease information to the pork industry. 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 or contact Dr. Paul Sundberg at [email protected]. For the original article, visit