The Swine Health Information Center, in collaboration with the American Association of Swine Veterinarians, hosted a webinar entitled “Senecavirus A as an emerging disease risk for FMDV” on March 26, 2026 and is now available for on-demand viewing here. The webinar addressed Senecavirus A as a cause of vesicular disease in swine and the need for diligence to differentiate it from foot-and-mouth disease virus, a foreign animal disease of concern to US pork producers. The webinar had 221 registrants from 19 countries and was conducted in cooperation with the staff at the Swine Medicine Education Center at Iowa State University.
SVA was first identified in US swine in 2015 and is considered a significant health threat due to its similar clinical appearance to FMD. Recent monitoring has shown a change in SVA detection trends, warranting continued surveillance. Understanding the virus, its pathogenesis, routes of transmission, disease trends, as well as control and mitigation steps, can help producers protect their herd from this emerging disease and enhance prevention for other vesicular diseases such as FMD.
Key takeaways include:
These characteristics highlight the importance of surveillance, confirming diagnostics, and biosecurity measures to mitigate the impact of SVA and to differentiate it from high-consequence foreign animal diseases.
Presenters offering their expertise included:
Diego Diel, DVM, MS, PhD, Professor, Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University
Ann Carpenter, DVM, MPH, DACVPM, Veterinary Medical Officer, Swine Health Team, Aquaculture, Swine, Equine, and Poultry Health Center, USDA APHIS Veterinary Services
Mariana Kikuti, DVM, MPH, PhD, Assistant Professor, Department of Veterinary Population Medicine, University of Minnesota
Rafael Romero Nicolino, PhD, Visiting Scholar, Iowa State University, Federal University of Minas Gerais, School of Veterinary Medicine – Brazil
Senecavirus A is a vesicular disease of swine belonging to the genus Senecavirus within the Picornaviridae family and has a small, positive-sense RNA genome of approximately 7.2 kb. SVA was first identified in 2002 as a contaminant in cell culture during investigations into cancer therapies. The emergence of SVA as a significant swine pathogen began in earnest around 2014, when outbreaks in Brazil caused vesicular disease clinically indistinguishable from FMD. The virus was then detected in the US mid-2015 with more than 5,000 confirmed cases documented since that time. This sharp increase underscores the growing importance of SVA in swine health and its role in triggering foreign animal disease (FAD) investigations due to its resemblance to FMD lesions.
Dr. Diel provided an overview for the clinical presentation of SVA noting that infection produces vesicular lesions on the snout, feet, and coronary bands of pigs, making it indistinguishable from other vesicular diseases like FMD without laboratory testing. This diagnostic challenge has major implications for regulatory responses, as any suspected FMD case requires mandatory reporting and investigation. Thus, detection of vesicular lesions from SVA contributes significantly to the burden of FAD investigations in the US swine industry.
Dr. Diel reviewed SVA pathogenesis and shared insights into the potential persistence in certain tissues and its role for disease transmission. Following inoculation, pigs develop a short-lived viremia typically lasting from approximately three to 10 days post-infection, with virus found in oral, nasal, and fecal secretions. Peak viral loads and shedding are observed early in infection, generally within the first week. SVA can be detected in multiple organs, but there is a notable tropism for lymphoid tissues, especially the tonsils. Virus can persist in tonsillar tissue beyond the acute infection phase and can be detected in animals for extended time periods. This finding is critical for understanding how SVA may persist within herds even after clinical signs have resolved.
Persistently infected animals can transmit SVA to naïve contacts even when low-level or subclinical infections occur and can contribute to disease spread within a population. In addition, SVA has been found in boar semen and highlights potential for semen-mediated transmission, particularly in systems using artificial insemination, which emphasizes the need for monitoring and biosecurity in boar studs.
Dr. Carpenter reviewed the challenges with differentiating SVA from other vesicular diseases of swine such as FMD. Mandatory reporting to USDA or a state animal health official is required if vesicular lesions are noted in swine. FAD investigations reflect seasonality of case detections with peaks occurring during summer months. Many of the investigations are overrepresented at slaughter establishments versus on-farm and cull sows represent a higher rate of investigation than market hogs. Standardized investigations are ongoing to determine the risk factors for disease detection and transmission in order to prevent further case presentation.
Dr. Carpenter provided an overview on the global FMD status and how the changing picture of disease detection across the globe is concerning. Various serotypes are identified in differing regions and the understanding of why a serotype departs from its existing “pool” of virus is limited. Vigilance for detection and diagnostic confirmation of vesicular lesions of swine continues to be critical to prevent FMD entry into the US especially with increasing global disease activity.
Dr. Kikuti reviewed the 10-year SVA trends for breeding herds from the SHIC-funded Morrison Swine Health Monitoring Project (MSHMP) data. Initially, a 2019 survey showed 17% prevalence of SVA in breeding herds and 7% in grow-finish. However, little data was available to determine how much virus circulation occurred in the US. The MSHMP data gathers case information from four diagnostic laboratories. Despite its clinical significance, the cumulative incidence of SVA in US breeding herds remained low, generally less than 2.5% per year across the 10-year study period. This suggests that while SVA continues to circulate, it affects a relatively small proportion of breeding herds annually. For sites experiencing more than one SVA outbreak, the median time interval between outbreaks was approximately 402 days, highlighting the potential for re-introductions and/or persistent circulation within herds.
Dr. Kikuti noted that a temporal pattern was observed, with peak SVA incidence occurring during the third and fourth quarters of the calendar year (July to December), suggesting seasonality influences disease transmission dynamics. A compilation of reports from multiple VDLs further supports this observation, with a consistent increase in the frequency of SVA cases during summer months. This seasonality requires further investigation and underscores the ongoing need for robust and collaborative surveillance systems that integrate on-farm observations with laboratory diagnostics to provide a comprehensive picture of SVA dynamics. Specifically, the observed seasonality and regional concentration suggest opportunities for more targeted biosecurity enhancements and surveillance efforts, particularly in the Midwest during the latter half of the year.
Dr. Nicolino provided an overview of Brazilian pork production, noting that farms are concentrated within the south, southeast and central regions of the country. SVA impacts swine of all ages with varying rates of morbidity and mortality depending upon the age of the pig. Three waves of SVA outbreaks occurred between 2014 to 2020 with differing regions affected. Piglets were impacted by SVA during the second wave of outbreaks in late 2018 with more than 50% of piglets exhibiting diarrhea. There is currently one vaccine commercially available for use in swine that has shown to increase antibodies 7-14 days after vaccination, but there has been limited evaluation of the effects post-challenge.
In Brazil, SVA surveillance is based on syndromic surveillance of disease, with all suspect cases being notifiable to animal health authorities. SVA in Brazil’s pork production follows a similar seasonal pattern to the US, reflective of warmer weather months. Risk factors contributing to this pattern are unknown but potential risks associated with infection could include animal movements, high replacement rates, poor sanitation and vector control. Dr. Nicolino noted that there is no current control program for SVA. Instead, producers focus on implementation of appropriate steps for FMDV prevention and utilize multiple biosecurity steps for those efforts.
More information on SVA research and resources can be found here.
The Swine Health Information Center, launched in 2015 with Pork Checkoff funding, protects and enhances the health of the US swine herd by minimizing the impact of emerging disease threats through preparedness, coordinated communications, global disease monitoring, analysis of swine health data, and targeted research investments. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. For more information, visit http://www.swinehealth.org or contact Dr. Megan Niederwerder at [email protected] or Dr. Lisa Becton at [email protected].