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It takes a team to keep FADs at bay

Finding out what disease pathogens are concerning hog farmers from around the world can better prepare the U.S. swine industry to prevent their spread to our shores.

October 26, 2016

14 Min Read
It takes a team to keep FADs at bay
<p>This map shows the main pathogens of concern to the swine industries in the respective regions&nbsp;of the world.</p>

Any disease can have U.S. swine producers on the edge of their collective seat, but the importation of a foreign animal disease could be just the thing that brings the industry to a screeching halt. With that in mind, keeping FADs out of our country is a big first step. Knowing the risks that are out there is key to keeping FADs from reaching our shores, and potentially infecting the U.S. swine herd.

The Swine Health Information Center was founded in the summer of 2015 with the mission “to protect and enhance the health of the U.S. swine herd through coordinated global disease monitoring, targeted research investments that minimize the impact of future disease threats and analysis of swine health data.”

Paul Sundberg, SHIC executive director, says monitoring the global pig pathogen picture was a task SHIC, or more specifically the organization’s Swine Health Monitoring and Analysis Working Group, took on to discover just what risks exist. Part of what that group is charged with is “assessing foreign, transboundary production disease risk using information from a variety of sources. The outcome of this assessment is the ongoing prioritization of the Swine Disease Matrix.” That matrix includes a list of the viruses that are known to be able to infect swine, most of them affecting health and production.

Knowing what risks are present, and taking precautions is better than getting caught flat-footed and having to react once a pathogen hits our shores. “We know there was PED [porcine epidemic diarrhea] in China in 2012-13 that was circulating, but we didn’t pay attention to it. We don’t want to repeat that mistake,” Sundberg says.

The expertise and reach of the 20-some volunteers in this working group were used to gather opinions from around the world as to what pathogens exist to potentially threaten the U.S. pork industry. This working group is made up of producers, university researchers, veterinarians, staff from veterinary diagnostic laboratories, and USDA staff, as well as staff members from the National Pork Board, National Pork Producers Council and the American Association of Swine Veterinarians.

Sundberg says a simple survey was developed where “people on the ground, on the farms in the various countries were asked to identify up to the top five diseases that you’re dealing with in your country or area, how are you managing those things, and what other diseases, though they may not be on the top five list, are still on your radar of ones that could present problems in the future.”

Completed surveys were then tabulated by Sundberg to get a clearer picture of what is going on in the world in the name of pig pathogens.

“Keep in mind that these are opinions from the people on the ground in these countries, but if a number of respondents shared common concerns of pathogens in their countries, then we had a pretty good idea of the concern in that country,” he says. For example, mycoplasma was rated high by individual respondents from South America, but it also appeared on numerous other South American respondents’ replies, though maybe not a top concern. “So, yes, we looked at the individual concerns, but if others from the same country or region shared the same concerns, then it painted a better picture of what that country is facing,” he says. Sundberg says pathogens were given a weighted average, based on the priority of the pathogens from the respondents and the number of responses within a region.

The Monitoring and Analysis Working Group sought to create a pathogen picture from China/Southeast Asia, Europe/Russia, South America and North America (Canada and Mexico).

As an example of the numerical weighted average given to pathogens, porcine reproductive and respiratory syndrome topped the concern for Europe/Russia with a weighted average of 6.00. PRRS was far and away the main concern in that region as Actinobacilus pleuropneumoniae was the second-ranked pathogen of concern there, but was a distant second with a 0.80 weighted average.

“Even though PRRS is of major concern in Europe/Russia, so are other pathogens that were listed on the surveys,” he says. “Swine influenza, for example, was ranked third on the pathogens of concern for Europe/ Russia [0.70 weighted average], but it is still a concern.”

As mentioned before, respondents were asked to rank their top five pathogens of concern, in addition to other pathogens they are watching, so Sundberg says that shows countries around the world are dealing with a laundry list of pathogens. “We need to be conscious of that because the U.S. is not only at risk for the highest rated pathogens in these countries,” he says. “Whether a pathogen is happening in only one area or in every country, we need to take a look at it, because the U.S. swine industry is at risk from all of these pathogens.”

Sundberg says the survey results did not reveal any surprises as in new pathogens that have surfaced around the world, but rather, “we’ve heard about these concerns, we know what’s going on around the world.” Sundberg did say the “ah-ha” moment came “that in my opinion, we’ve got a fairly good handle of what’s going on in the world — at this moment. I have no delusion that there aren’t other things going on in the pig populations around the world that did not show up on this list, but that we have to be on the lookout for. So the survey can’t be taken to mean that we know everything. The survey did not point out big surprises; it pointed out ongoing risks and ongoing concerns.”

Though Sundberg is confident the U.S. swine industry is cognizant of risks out there, we cannot get lackadaisical in our efforts. “We can’t let our guard down. … we can’t be so tunnel-visioned that we lose track of the all the risks that are out there.”

Battling worldwide swine pathogens is a team effort, and the USDA Animal and Plant Health Inspection Service Veterinary Services is formulating an Emerging Animal Disease Preparedness and Response Plan that is still in the developmental stages. A draft of the plan can be read at aphis.usda.gov/animal_health/downloads/emerging-dis-framework-plan.pdf.

According to the USDA, the “purpose of this plan is to define the processes by which the Veterinary Services unit of the USDA’s APHIS will identify, evaluate and respond to emerging diseases in animal populations, and the implementation of these processes as a VS core business practice. This plan will help VS respond effectively to emerging animal diseases by outlining processes to be used to determine appropriate response activities. The framework for this plan was outlined in 2014 in the APHIS concept paper, “Veterinary Services Proposed Framework for Response to Emerging Animal Diseases in the United States.”

Sundberg says the USDA’s efforts do not appear to be a duplication of the industry’s efforts. “There may be some things that SHIC will be able to respond to more quickly than what the USDA is able to, and there may be some things that the USDA can go a little more in-depth on than the center. We are working together to at least minimize duplication, and make both programs as synergistic as possible.”

USDA’s Veterinary Services is seeking comments on the plan by Nov. 1.

SHIC has been in existence a little over a year, and Sundberg looks at the success of the organization from the aspect of how it has been received in the U.S. swine industry.

“One of the biggest successes of SHIC so far has been the collaborative efforts of the entire industry. Everyone has been working together. Almost without exception when I contact someone, give them a call, send them an email, and ask them for help, tell them that the Center needs this or the U.S. pork industry needs this in order to help answer these questions, people have been more than willing to help. It’s been very gratifying to see the collaboration and cooperation and getting behind the efforts of the center.”

SHIC’s website — swinehealth.org — also has more information on the Swine Disease Matrix, with fact sheets available on many of these pathogens and other SHIC programs and projects.

How do they get here?

Knowing that a laundry list of pathogens of potential risks exists is one thing. Knowing how to prevent them from coming to the U.S. is another thing completely.

Scott Dee, a veterinarian with Pipestone Applied Research, Pipestone Veterinary Services in Pipestone, Minn., is fervently searching for answers to how FAD pathogens may come into our country.

Building on previous research where he and researchers at the Animal Disease Research and Diagnostic Laboratory at South Dakota State University in Brookings proved that porcine epidemic diarrhea virus can survive in contaminated feedstuffs, new research is looking to see if the same is true with FAD pathogens.

Background research

Scott Dee has led a number of research projects looking at, and proving, the viability of porcine epidemic diarrhea virus in feed and feed ingredients. All of these projects have lead up to the current four-phase project investigating if foreign animal disease viral loads may also survive in feed ingredients.

Can PEDV ride the wave with feed ingredients?

PEDV viability in feed ingredients researched

Proof of concept: Feed can carry PEDV

In the PEDV research, Dee and scientists of South Dakota State University used PEDV to contaminate multiple feedstuffs during the simulated shipment of the feedstuffs from China to the United States. This latest project — funded by SHIC, AASV, Kemin and Kansas State University — enlists surrogate viruses to mirror actual FADs under the guidance of Dee, Eric Nelson and Diego Diel. For example, Seneca Valley virus was used as a surrogate of foot-and-mouth disease, which would cripple the U.S. swine industry if it actually infected the swine herd. The other two FAD surrogates included in this phase of research were bovine viral diarrhea virus in place of classical swine fever virus and bovine herpesvirus-1 in place of pseudorabies virus.

Through all four phases of this current project, a total of 10 different viruses are being put through the simulated oceanic voyage. Phase 2 was set to start Oct. 24.

Dee went into this research with the hypothesis that survival will depend on the correct combination of pathogen and ingredient. Having the knowledge that the previous PEDV research presented, Dee says Phase 1 of this latest research has shown some consistency, but also some variability across the different viruses being tested. “I thought that strengthens the validity of the model, when you start to see variations across the viruses and the ingredients with some consistencies,” Dee says.

“I was a little surprised by the stability of the Seneca Valley virus. It’s not enveloped, so I knew it was going to be a little bit more resistant, but the fact that we found it in all but a couple samples, that was intriguing.”

An enveloped virus, such as BVDV, showing up negative across the board of all the shipped ingredients was not a surprise to Dee. “That is probably a good indication why we have not had hog cholera come here,” he says. “This suggests that it cannot survive the journey through feedstuffs.”

Researchers test FADV surrogates

This latest research project intends to find if foreign animal disease viruses can be transmitted on a global scale in feed ingredients. Due to biosecurity concerns, researchers choose not to use viral doses of the FADs themselves, but rather a surrogate virus that has properties similar to the actual FAD. The surrogates used for the FAD are in parentheses. Vesicular stomatitis virus and circovirus will be used in their current form.

The test on the first three viruses has already been completed, with the remaining seven to be completed over the next few months.

1. Foot-and-mouth disease virus (Seneca Valley virus)

2. Classical swine fever virus (bovine viral diarrhea virus)

3. Pseudorabies virus (bovine herpesvirus-1)

4. Nipah virus (canine distemper virus)

5. Swine vesicular disease virus (enterovirus)

6. Vesicular exanthema virus (feline calici virus)

7. Vesicular stomatitis virus

8. Circovirus

9. PRRS virus (174)

10. African swine fever virus (vaccinia virus)

In looking at ingredients that FAD viruses may latch on to, Dee looked at ingredients that would typically be on a voyage from Beijing — most common, some unusual. Included in the research were conventional and organic soybean meal, soy oil cake, distillers dried grain with solubles, lysine, choline, vitamin D, moist dog and cat food, dry dog food, pork sausage casings, complete feed (positive control), complete feed (negative control) and a stock virus (positive control).

One result made Dee smile — none of the three stock viruses survived the journey by itself, similar to the previous study that showed PEDV also did not survive the trip. “In the absence of a feed matrix, the virus doesn’t live,” he says. He is curious to see if this trend of stock virus non-survival will hold true for the remaining seven viruses yet to be tested.

Just as in the PEDV study, 5 grams of each ingredient was inoculated with 100 microliters of virus. There were four batches of each ingredient (Day 2 post inoculation, Day 8 PI, Day 25 PI and Day 37 PI), so researchers can test for viral presence at various points in the “journey” or the completion of the journey. Samples were placed in an environmental chamber at the SDSU lab, with historical data of temperature and relative humidity programmed to mimic the variations of an actual oceanic trip.

A few pathogens will undergo the research, without the use of a surrogate: vesicular stomatis virus, circovirus and PRRS virus strain 174.

Phase 2 will put Nipah virus, vesicular exanthema virus, African swine fever and vesicular stomatitis virus to the test, to be followed by Phase 3 with PRRSV, PCV2 and SVDV.

The final phase of this research will seek to provide solutions to handling certain viruses that survive the simulated oceanic journey. Dee says after all 10 viruses have been tested, mitigation strategies will be applied to select high-risk ingredients and surrogates. Such strategies to be applied will be Sal CURB (a Kemin product that is a blend of aqueous formaldehyde and organic acids) and a medium chain fatty acid blend from Kansas State University, among possible other strategies.

Phase 4, and the complete study, is not expected to be done until next spring.

What to do in worse case

Close communication between a hog producer and the herd veterinarian in imperative for the health of the hogs. That communication is even more important when something goes wrong in the herd.

In a serious enough situation, veterinary diagnostic laboratories get involved, and quick diagnosis and exchange of information can prevent the presence of a new disease from becoming an even bigger issue.

Rodger Main, with the VDL at Iowa State University, stresses the need for standardization of data and messaging from VDLs, and that is the goal of the Swine Diagnostic Data Standardization Project, a highly collaborative project that started July 1 and will conclude next fall.

The objective of the $700,000, 15-month project funded by SHIC and USDA is to establish and adopt universally recognized diagnostic data standards and systems of electronic messaging necessary for transcending inter-laboratory connectivity and the next generation of web-based swine health information management tools for both non-program disease and program disease applications.

“Our primary focus is to create a common set of standards so that data looks the same regardless of its source. There is no level of standardization right now,” Main says.

Main says such standardization has been used in human medicine, but not in veterinary medicine. “Once it gets standardized, maintenance is relatively minimal. But we haven’t done the up-front project.”

This project’s primary goal is to enhance utility of information for any of the number of database applications currently being used, and it can be evolved for those in the future. Standardization of the data and analysis will be integral if a new disease, say an FAD, surfaces within a swine herd, when immediate response is critical.

“Fruits of this will be harvested for years to come,” Main says. “Going forward in the information age, it’s really going to be imperative that we can move and organize the data seamlessly and do it electronically. One of the challenges of diagnostics labs in particular is that the only way to get data from multiple sources into a common location is you have to map through a web service, and by lab, by test, and then any time that lab may change something, you may not know it. So you have to go back and remap it. So that’s a big reason to standardize data for continuity.”

Sundberg, Dee and Main offered presentations on these topics at the Allen D. Leman Swine Conference in St. Paul, Minn., in September.

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