AASV Swine Health Committee Considers SVV

September 9, 2015 — 

The Swine Health Information Center (SHIC) asked the AASV Swine Health Committee (SHC) to evaluate the status and possible responses to the recent Seneca Valley Virus (SVV) cases. The committee met by conference call on September 8, 2015 and was presented with 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 ISU-VDL and the U of MN VDL. Each lab 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, coronary band and/or hoof) submitted to the diagnostic lab during the week of 8/24/2015. Samples submitted from numerous states tested PCR positive.

The committee concluded that early evidence suggests SVV is a widespread Emerging Swine Production Disease (ESPD) fitting the criteria of a TYPE 3 emerging disease outbreak. Those criteria include:

• Widespread areas of infection, and/or infections that are geographically and epidemiologically distinct, detection involves a large portion 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 one year to develop the needed tools and information to mitigate negative effects of the disease on swine health, welfare and producer profitability.

[NOTE: the TYPE 1, 2 and 3 designations are derived from a draft Emerging Disease Response Plan being developed through a joint effort involving AASV, NPB, NPPC, SHIC and USDA.]

The clinical signs and gross lesions of SVV are indistinguishable from vesicular foreign animal diseases (FAD) including foot and mouth disease, vesicular stomatitis, and swine vesicular disease making rapid response and differential diagnosis imperative. Complacency in continuing to monitor for FADs could be devastating to the livestock industry of the U.S. So, cases presenting similarly to FMD, VS or SVD must be treated as such until the FADs can be ruled out. The AASV SHC concurred that the observation of vesicles in pigs should be treated as a potential FAD necessitating the following activities:

Herd veterinarian roles and responsibilities:

• Intensive observation of pigs looking for gross lesions and clinical signs
• Upon encountering a suspect case in finishing pigs or sows, the veterinarian should:
  • Stay at the site
  • Stop all people, vehicular and animal movements
  • Call the state or federal animal disease control officials and follow their instructions.
• Once the disease has been determined to not be an FAD:
  • As with any clinically sick animal, SVV positive animals exhibiting clinically-active lesions should not be shipped to slaughter.
  • Once lesions are resolving, communication with the slaughter plant should be initiated before shipping. Communication among the slaughter plant, the Food Safety Inspection Service (FSIS) and the state animal health official will confirm the qualification for accepting the pigs at the plant. FSIS is currently working to determine what documentation may be necessary to verify the pigs have had an FAD investigation with negative results.

Producer roles and responsibilities:

• Do not move animals which are ill or exhibiting clinical signs including clinically active lesions
• If possible, segregate/isolate affected animals on the site
• Document movements leading up to and immediately surrounding the onset of clinical signs as the information may be useful in disease analysis or the FAD investigation.
• Cooperate with sample collection and submission as part of the FAD investigation under the direction of a state or federal animal health official.

Additional guidelines are available in the document entitled Procedures to Report a Suspected Foreign Animal Disease on the AASV website.