This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.
The MSHMP team, Mariana Kikuti, Xiaomei Yue, Marcello Melini, Sarah Vadnais, Paulo Lages, and Cesar A Corzo, share their latest update on Senecavirus A in the U.S.
Key Points:
- From 2015 to 2024, the cumulative incidence of SVA in U.S. breeding herds is low overall (<2.5% per year).
- SVA outbreaks primarily occur in the Midwest, peaking in the third and fourth quarters annually.
- No new breeding herd cases have been identified in 2025 based on MSHMP reports and VDL surveillance data.
Introduction
Since our last Senecavirus A (SVA) update in January 2025, we have incorporated additional data into our analysis, including the remaining 2024 data and updates through May 2025. Thus, we updated our estimates of the breeding herd SVA cumulative incidence in the U.S. to better characterize the disease burden and begin outlining prevention and control measures.
Methods
Diagnostic data from the University of Minnesota and Iowa State University VDLs (January 2015–May 2025), along with SVA cases reported by MSHMP participants over the same period, were analyzed. VDLs SVA PCR submissions during the period excluded environmental samples, isolates, and miscellaneous specimens from the incidence estimations. An SVA outbreak was considered if a positive SVA submission was detected or if a site reported an SVA outbreak directly to MSHMP. Positive submissions from the same site that were submitted within twelve weeks apart were considered to be representative of the same outbreak. Yearly cumulative incidence was calculated using the number of breeding herds reporting statuses to MSHMP for either PRRS, PED, or SVA (i.e., sites sharing information for at least one of the primary diseases monitored by MSHMP) as the denominator.
Results
After deduplicating cases identified by VDL and reported to MSHMP, 114 SVA breeding herd outbreaks were detected in 74 sites from 15 production systems across 12 states. Most outbreaks occurred in the third and fourth quarters of the calendar year, followed by the first and second quarters, with variations in the quarterly incidence of SVA observed across different years (Figure 1). The majority of outbreaks detected originated in the Midwest (92.11%), followed by the South (7.02%) and the Northeast (0.88%). No new breeding herd cases have been identified in 2025 up to May based on MSHMP reports and VDL surveillance data.
Discussion
While the overall yearly incidence remains low (<2.5%, Figure 2), the virus continues to impact swine populations. The temporal and regional patterns suggest possible seasonal fluctuations and a regional burden, emphasizing the need for continued surveillance to better understand SVA dynamics across the country. Further research should focus on expanding surveillance to include growing pig herds and investigating the potential factors contributing to the observed regional and seasonal variation.
The full paper can be found at: https://www.mdpi.com/2076-2615/15/11/1650