At the risk of foreign animal disease (FAD), and specifically African swine fever (ASF), information overload, I will continue the “Glass half full” series. It is simply amazing the groundswell of activity and information within the industry since ASF infected and swept through China over 1 year ago. Previously, I described the 3 likely primary risks of ASF entry into our country and the significant biosecurity breakdown that would have to occur for the virus to make the giant leap onto at least one pig farm.1 Now, I would like to review some of what is being done for ASF preparedness and response if an outbreak were ever to occur.

USDA's functional exercises

This 4-day ASF exercise is still a couple of weeks away as I write this. This is the culmination of 3 previous exercises, which began last fall and were designed to target key areas of ASF response and mitigation.2 I am sure many AASV members will be involved in the challenges and potential chaos of this 4-day event. I look forward to the lessons learned and strengths and weaknesses revealed from the exercise among the 14 participating states.

FAD response plans

The US Department of Agriculture’s (USDA) Disease Response Strategy-African Swine Fever is called the “green book” and is a living document that provides strategic guidance for responding to an ASF animal health emergency in the United States.3 It is a thorough treatise on the nature of the virus and disease, control, eradication, and recovery. It follows the World Organisation for Animal Health’s (OIE) Terrestrial Animal Health Code definitions and guidelines. I encourage you to read it.

Likewise, each state has a tailored FAD response plan.4 Minnesota's plan emphasizes the unique cooperative relationships between the Minnesota Board of Animal Health (BAH), Minnesota Department of Agriculture, and USDA Veterinary Services. Minnesota alone has had 59 FAD investigations from January through August, of which 53 were vesicular cases according to the Minnesota BAH (B. Peterson, oral communication, August 2019).

Like other states, Minnesota has developed an Emergency Disease Management Committee (EDMC) to act as an advisory group to the BAH. Committee members are from the swine industry and regulatory agencies. This advisory group will help build trusted relationships and expertise prior to an emergency to lead a more effective response in case of an ASF outbreak.

The EDMC consists of 10 subcommittees tasked to address the following critical activities of an outbreak response: 1) communications; 2) surveillance and diagnostics; 3) information management including epidemiological investigations, mapping, and tracing; 4) health, safety, and welfare of pork producers, veterinarians, disease responders, and animals; 5) biosecurity and quarantine; 6) permitted movement control as part of risk-based disease management and pork production strategies; 7) mass depopulation, euthanasia, and disposal; 8) cleaning and disinfection; 9) wildlife management and vector control; and 10) regionalization or compartmentalization for interstate and international trade. I share this list to emphasize the plethora of information and expertise needed in case of a real FAD outbreak.

As an example, the surveillance and diagnostics subcommittee is addressing issues such as early identification of the index case. Currently, the National Animal Health Laboratory Network can test for ASF virus via whole blood, tonsil, spleen, and gastrohepatic, inguinal, and mesenteric lymph nodes. According to Dr Jerry Torrison (oral communication, August 2019), blood swab assays could be very sensitive and specific but are not yet considered official tests. Oral fluid assays have not yet been validated. At the University of Minnesota’s Veterinary Diagnostic Laboratory, active surveillance occurs with about 40 ASF assays per week on sample submissions from practitioners and slaughter plants (oral communication, J. Torrison, August 2019). Is this enough active surveillance for early ASF detection? Probably not. Confirming an infected ASF herd within the first 10 days vs the first 30 days of exposure will make a tremendous difference in the number of herds infected and the subsequent economic damage.

Where will the resources (eg, people and lab tests) come from for diagnostic surveillance during and after the initial 72-hour shutdown? A primary limitation in a large FAD outbreak is enough qualified veterinarians or technicians to obtain the appropriate type and number of samples within the surveillance zones and to epidemiologically trace back and trace forward any and all suspect pig sites. In Minnesota, there are only 10 FAD diagnosticians with the BAH or USDA to make a confirmatory FAD diagnosis. Some states are considering allowing accredited swine veterinarians to train certified authorized agents to fill this people power void in case of an emergency. Further guidance is needed, but it could be another important role for swine veterinarians.

How would we respond? It is difficult to predict what an ASF outbreak in the United States would look like, but here are some key points:

• The index case could be identified by you (or me) or one of our clients. Hopefully not at a packing plant.
• The United States has some of the best swine farm and truck biosecurity practices in the world. However, an ASF outbreak will likely be due to a lapse in biosecurity somewhere. This cannot be emphasized enough with our clients.
• An FAD laboratory will confirm the diagnosis and an FAD diagnostician will establish infected, buffer, and surveillance zones. Chaos at some level will likely ensue.
• There will be a temporary 72-hour shutdown on movements. This could be local or widespread depending on the situation. Try to establish with each of your clients what to do if this happens. Also review an individual site plan for euthanasia and disposal.
• Permitted movements may resume on day 4 if allowed by the Incident Commander only. Everything, including sites, packing plants, and diagnostic cases, must be associated with a premises identification number for movement. Having a Secure Pork Supply Plan in place will help expedite pig movements.

The end game – elimination

The US swine industry has export market economic incentives to eliminate OIE reportable diseases. I believe there would be an all-out effort to do so quickly. The process of cleaning and disinfection, naïve sentinel exposure, and restocking each swine herd will likely take months, but we will learn how to do it as efficiently as possible. The United States has had significant historical success in eliminating previous swine FADs.5 Although not in swine, the most recent, most expensive, and arguably the most significant animal health event in US history was highly pathogenic avian influenza. It was eliminated over 13 months at a direct cost of $1.6 billion to turkey and layer-chicken flocks and about $3.3 billion indirect costs to the US economy.6 It is another success story of an FAD eradication.

African swine fever has successfully been eradicated from some countries. What can be learned from their efforts?

Spain and Portugal. Between 1985 to 1995, Spain successfully carried out an extensive coordinated program to eradicate ASF with the support of the European Union. This occurred even though ASF was present in their feral pig population and in the Ornothodoros tick vector. Many of the tests we use today for rapid detection in both swine and ticks come from Spain’s experience. Portugal became ASF-free in 1993 but had a small re-occurrence in 1999 likely from positive tick vectors, which can remain infective for over 600 days!7

Brazil. A successful ASF elimination program over 6 years (1980-1986) led Brazilian authorities to apply emergency sanitary measures in which 66,966 pigs were depopulated in 224 outbreaks of ASF in 3 southern states.8 Regionalization, as in Brazil, may be a useful tool for the United States in the case of an ASF outbreak.

Dominican Republic and Haiti. The closest geographically the ASF virus has come to the United States was in the Dominican Republic and Haiti around 1978. The disease was eradicated over 13 months through a cooperative effort by the United States, Canada, Mexico, and the Haitian government in which the entire pig population on the island nation was eliminated (400,000 were euthanized and 600,000 died from ASF).9 If ASF were to infect any North American country, the United States, Canada, and Mexico would be in it together.

The USDA’s Animal and Plant Health Inspection Service and the state agriculture and BAH departments deserve a lot of credit for coordinating and attracting industry participation in these efforts. The statement, “I’m from the government, and I’m here to help” is said with sincerity, not satire, regarding ASF preparation and response. The point of all of this is that even if the US swine industry has an ASF outbreak, my glass is half full. I am confident and optimistic that we will stay vigilant and do our best to prepare, control, contain, and eliminate ASF if it were to occur.

References

*1. Winkelman N. Glass half full (Part 1) – ASF prevention [editorial]. J Swine Health Prod. 2019;27:249-251.

*2. Participate in USDA’s full functional exercise for an African swine fever for agriculture response in September. American Association of Swine Veterinarians website. https://www.aasv.org/news/story.php?id=11867. Updated August 9, 2019. Accessed September 11, 2019.

*3. US Department of Agriculture. Disease response strategy African swine fever. https://www.aphis.usda.gov/animal_health/emergency_management/downloads/asf_strategies.pdf. Published March 2019. Accessed September 11, 2019.

*4. Minnesota Board of Animal Health. Minnesota FAD response plan. https://www.bah.state.mn.us/media/MN-FAD-Response-Plan-2019.pdf. Updated January 2019. Accessed September 11, 2019.

*5. Connor J. 50+ years of US swine disease eradication. AASV Proc. Lake Buena Vista, Florida. 2019:445-448.

*6. US Department of Agriculture. Final report for the 2014-2015 outbreak of highly pathogenic avian influenza (HPAI) in the United States. https://www.aphis.usda.gov/animal_health/emergency_management/downloads/hpai/2015-hpai-final-report.pdf. Updated August 11, 2016. Accessed September 11, 2019.

*7. Hess A. African swine fever: How did the Spaniards eradicate it? National Hog Farmer website. https://www.nationalhogfarmer.com/business/african-swine-fever-how-did-spaniards-eradicate-it. Published November 30, 2018. Accessed September 11, 2019.

8. De Paula Lyra TM, Saraiva VEV, Hermida Lage GR, Samarcos MSR. Eradication of African swine fever from Brazil. Rev Sci Tech Off Int Epiz. 1986;5(3):771-787.

*9. Ebert A. Porkbarreling pigs in Haiti. The Multinational Monitor. 1985;6(18). https://www.multinationalmonitor.org/hyper/issues/1985/12/ebert-porkbarrel.html. Accessed September 11, 2019.

* Non-refereed references.

Nathan Winkelman, DVM
AASV President