The American Association of Swine Veterinarians (AASV), National Pork Board (NPB), National Pork Producers Council (NPPC), and Swine Health Information Center (SHIC) have been working collaboratively with federal and state animal-health officials, food-safety inspectors, packing-plant officials, and laboratory diagnosticians to address the recent increase in Seneca Valley virus (SVV) cases. Historically, vesicles in pigs automatically led to a suspicion of foot-and-mouth disease (FMD). This suspicion is less clear-cut with the recent increase in positive SVV cases. Seneca Valley virus is clinically indistinguishable from the vesicular foreign animal diseases (FADs) of swine, including FMD, vesicular stomatitis (VS), and swine vesicular disease (SVD). Therefore, it is imperative that veterinarians and producers continue to respond to vesicular lesions as if they represent an FAD until proven otherwise. Remember, accredited veterinarians are required to report the presence of vesicular lesions in swine to animal-health officials.
The challenge, from a regulatory standpoint, is how to ensure prompt investigation of vesicular cases while not unnecessarily delaying movements of animals determined to be negative for an FAD. This involves state animal-health officials, United States Department of Agriculture’s (USDA’s) Animal and Plant Health Inspection Service, and Food Safety and Inspection Service (FSIS) personnel, as well as accredited veterinarians and packing-plant officials. As I am writing this article in November, USDA is drafting a guidance document to describe how they plan to address these challenges.
While we await guidance from USDA, the AASV Swine Health Committee (SHC), at the request of SHIC, evaluated the status of, and possible responses to, the recent SVV cases. The committee met by conference call on September 8, 2015, and provided up-to-date information regarding the most recent cases as well as the results of a PCR survey of oral-fluid samples conducted at both the Iowa State University Veterinary Diagnostic Laboratory and the University of Minnesota Veterinary Diagnostic Laboratory. Each laboratory retrospectively tested approximately 1000 oral-fluid samples from swine not reported to be exhibiting clinical signs indicative of SVV (acute lameness accompanied by vesicular lesions on the snout or coronary band or hoof or both) submitted to the diagnostic laboratory during the week of August 24, 2015. Samples submitted from numerous states tested PCR-positive.
The committee concluded that early evidence suggests SVV is a widespread emerging swine-production disease fitting the criteria of a TYPE 3 emerging disease outbreak. Those criteria include the following:
- Widespread areas of infection, and/or infections that are geographically and epidemiologically distinct, involving a large proportion of swine-production centers in the United States.
- There is inadequate knowledge about the disease, how it spreads, effective prevention and/or control measures, and risk pathways for disease entry and spread.
- There is little to no likelihood of controlling the disease using quarantine, stop movement, or depopulation, and no known or effective vaccine, treatment, or control strategies.
- It is expected to take greater than 1 year to develop the needed tools and information to mitigate negative effects of the disease on swine health and welfare, and producer profitability.
Note: the TYPE 1, 2, and 3 designations are derived from a draft Emerging Disease Response Plan under development through a joint effort involving AASV, NPB, NPPC, SHIC, and USDA.
Complacency in continuing to monitor for FADs could be devastating to the livestock industry of the United States. The AASV SHC determined that observation of vesicles in pigs should continue to be treated as evidence of a potential FAD, necessitating the following activities.
Herd veterinarian roles and responsibilities:
- Intensive surveillance for gross lesions and clinical signs (observe the pigs).
- Upon encountering a suspect case, the veterinarian should
- Call the state or federal animal-disease control officials,
- Stay at the site to await instructions from state or federal animal-health officials, and
- Stop all human, vehicular, and animal movements.
- Once the disease has been determined to not be an FAD,
- As with any clinically sick animal, SVV-positive animals exhibiting clinically-active lesions cannot be shipped to slaughter.
- Once lesions are no longer active, the state animal-health official(s) should notify the slaughter plant and the USDA FSIS of the diagnostic findings before the animals are shipped to slaughter, if healing erosions are still present. The FSIS is currently working to determine what additional documentation may be necessary to verify FAD-negative status.
Producer roles and responsibilities:
- Do not move animals that are ill or exhibiting clinical signs, including clinically active lesions,
- Segregate or isolate affected animals on the site (if possible),
- Disclose and report movements leading up to and immediately surrounding the onset of clinical signs,
- Allow for sample collection and submission, and
- Communicate with state and local officials.
Additional guidelines are available in the Procedures to Report a Suspected Foreign Animal Disease document on the AASV website (https://www.aasv.org/documents/FADReporting.pdf).
Harry Snelson, DVM
Director of Communications