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ASF is a highly contagious hemorrhagic disease of pigs that produces a range of clinical signs and lesions that closely resemble those of classical swine fever.
June 4, 2018
While foot-and-mouth disease may be grabbing the swine pathogen headlines and the National Pork Producers Council is pleading for more funding for a beefed-up FMD vaccine bank in the next farm bill, many other diseases could have a crippling effect on the U.S. swine herd.
One such disease is African swine fever. Even though the closest ASF has been to the U.S. was a case in Haiti in the early 1980s, it is still of great concern to the U.S. swine industry.
African swine fever is listed as the third-highest risk to the U.S. swine industry on the Swine Disease Matrix posted on the Swine Health Information Center website, behind only FMD and classical swine fever. ASF is a highly contagious hemorrhagic disease of pigs that produces a range of clinical signs and lesions that closely resemble those of classical swine fever.
Again, the disease is not in the U.S. swine herd, but it is steadily making its way across Eastern Europe since the virus was detected in 2007 in Georgia in the Caucasus region of Eurasia. Seven years later, the virus was detected in Latvia, Lithuania and Poland. Earlier this year, ASF was detected in a wild boar in Hungary.
Study abroad in Europe
To find out how the Eastern European swine industry is handling the movement of ASF, a U.S. delegation earlier this year traveled to Poland, Germany and Denmark.
“We made sure not to go anywhere that African swine fever was present,” says Barbara Determan, a pork producer from Early, Iowa; current president of the U.S. Animal Health Association; and past president of the National Pork Producers Council.
Though the delegation avoided areas where the virus was present, they did visit three countries where the local swine industry and governments are working to slow or halt the spread across the European Union.
This most recent trip was a follow-up to a similar trek three years ago when a U.S. delegation examined ASF activity in Latvia, Lithuania and Poland.
According to Liz Wagstrom, NPPC chief veterinarian, ASF is a concern, because like FMD, it is also a trade-limiting disease. “It would shut down trade for us,” she says.
Unlike FMD, ASF only infects pigs. ASF is spread through nose-to-nose contact, fecal-oral contact or a feral hog chewing on the carcass of an infected pig.
“It’s not as easily transmitted as FMD, so that maybe gives us more of a safety cushion, but we don’t want to minimize the risk,” Wagstrom says.
What’s concerning is the way ASF is spreading across Eastern Europe, in countries that are trading partners with the U.S. “Poland is a major exporting country, and so far they have kept it out of their commercial production,” Wagstrom says. “You look at Poland, Denmark and Germany as major exporting countries, and if ASF gets into their commercial production, the exporting becomes a real concern.” ASF is hardy in the environment, and it survives in meat. “We would not want to import meats from a zone where commercial pigs are infected within an ASF-positive country,” she says.
At South Dakota State and Kansas State universities, a recent study — led by Scott Dee, director of Pipestone Applied Research, and funded by the Swine Health Information Center — found the ASF virus can possibly survive in shipments of feedstuffs.
Wagstrom says a request has been made for USDA’s Animal and Plant Health Inspection Service to work with customs and border patrol to more closely scrutinize between shipments and from the Baltic region. “We would like to see increased inspections of those flights,” she says.
USDA has also been asked to conduct a compliance audit on Lithuania’s inspection system, which has been seen as equivalent to that of the U.S., “to make sure it is still up to par, since the United States does import cooked meats from Lithuania,” she says. “Cooked meats should be perfectly safe, but it would be comforting to have a compliance audit to make sure the meats have been cooked to temperatures and holding times that they’ve said it is.”
Determan and Wagstrom applaud the work done by the governments and swine industries in Denmark, Germany and Poland to thwart ASF’s spread. Europe does have the advantage over the U.S. in having a greater number of government veterinarians, Wagstrom says. “So they have a lot more central control in some of those countries; that allows them to be very firm and hard on their zoning.”
Europe takes disinfection a step further
Since porcine epidemic diarrhea ravaged the U.S. swine herd a few years back, producers and hog transporters have learned the importance of strengthened biosecurity and the role that washing and disinfecting of the trucks and trailers plays in keeping the herd healthy. Determan says she was impressed with even more stringent truck washing protocol instilled in the European culture.
“You always hear how stringent they are on their truck washes and their biosecurity, but you never know if that’s what they really do,” she says. “Well, to be at one [truck wash] and walk through the trailers to see what they are looking for, it was impressive.”
Wagstrom says Denmark exports about 10 million pigs a year, mostly to Poland and Germany for finishing. Upon return to Denmark, the trucks are washed, inspected and disinfected to ensure cleanliness. “Depending where they are coming from, the truck may also be required to have additional downtime before they go to a farm,” she says. Last year, over 26,000 trucks were washed at these stations.
Determan notes U.S. producers use truck washes, but it’s Europe’s attention to detail that sets it apart. When the U.S. delegation arrived at a truck inspection site on the Denmark-Germany border, they were told one truck failed an inspection. “They found four or five wood shavings, and a piece of straw,” she says.
This was after the truck had been washed and disinfected in Germany. The driver was told to return to Germany for another washing before being admitted to Denmark.
“I think as an industry we could do a better job of having more truck washes available. And once we have them built, let’s make sure that people know where they are,” Determan says. “I’ve had producers ask me in the past few months, ‘Hey, I’m bringing some pigs up that way, where is the nearest truck wash?’”
In Denmark, the truck washes are paid for by both the producers and the government.
Secure Pork Supply helps
The development of the Secure Pork Supply in the U.S. helps in the prevention of ASF and other swine pathogens. “Some of the same things that we would do under the Secure Pork Supply is what they [European countries] are doing — knowing the inventory, when they’re moving and where they’re moving,” Wagstrom says. “A good traceability system, I think, is very important. They are doing that.”
Strong biosecurity, however, is needed beyond barns and trucks to control the spread of ASF. “As for their preparedness, the EU has a lot of the tools that you can use in place,” says Patrick Webb, National Pork Board director of swine health programs. “The linchpin here — and the take-home message for us in the United States — is the wild boar. That is a big thorn in their side because the wild boar population is very hard to control, and they don’t care about country borders.”
Though ASF is not on U.S. shores, there are a lot of feral pigs in the country, “so we need to work on ways to get our feral hog population under control, because I could see similar things happen here if we were ever to get African swine fever,” he says. Webb says ASF may not be able to be eliminated among EU’s feral swine.
Wagstrom says locals in Europe thought that the disease would kill out the herd by itself, but that hasn’t happened, as “about 5% of the wild boars they are testing are pigs that are infected. But they have antibodies, so they have survived and can then spread it to others. … It hasn’t burned itself out as quickly as I think they had thought that it would.”
Methods to control the feral hog herd, or sounder, in the U.S. include baiting, hunting and trapping.
Hunters seek wild boar
In Poland and Germany, hunting wild boar is a large part of the culture, Wagstrom says, so much so that hunters and the pork industry have become competing interests. Hunters and hunting clubs want to improve boar habitat, while pork producers strive to control the spread of feral swine.
“You can just see it marching across the countries that have the boar hunting culture,” Wagstrom says. “It’s only a matter of time before the areas with commercial pigs in Poland has ASF, because not only can you see it moving in the wild boar population a few kilometers a month toward the east, [but] now there are also pockets near Warsaw, and they feel that it came in via meat from infected animals. Then it got into garbage that the wild boar got into. So, there’s human spread, and there’s spread through the wild boar movement.”
Webb believes Europe’s commercial producers are doing a good job to prevent the spread of ASF, “but your $64,000 question is how you handle your feral pig population.”
According to Wagstrom and Webb, the EU government is working with hunters so they are more mindful of the feral hogs they are hunting, even offering a reward if hunters stumble upon the carcass of a feral hog.
Citizens in Poland are “rewarded for reporting the finding of a wild boar carcass showing signs of ASF, so that mandatory diagnostics may be performed,” Wagstrom says. “Hunters can get up to 100 euros for reporting a possible infected feral pig.”
Also, field dressing of feral swine is prohibited, and offal needs to be disposed of in pest-proof containers.
Wagstrom says Poland and Germany are implementing laws requiring pig-proof fencing around commercial hog sites to keep feral pigs away from commercial herds.
Lessons learned from porcine epidemic diarrhea in the U.S. and how Eastern Europe is working to keep ASF at bay emphasize the need for tighter biosecurity and more research.
Webb says NPB’s Swine Health Committee many years back identified research for foreign animal diseases as a priority. With no vaccine for ASF, “you need to respond and control the disease with a heavy emphasis on biosecurity, because you wouldn’t have a vaccine as a tool to help there.”
Early detection key
Early detection is one of the best defenses against ASF, FMD and classical swine fever. A critically needed tool for early detection is oral fluids. A push is being made to get oral fluids validated for ASF, FMD and CSF.
“Vaccine and diagnostics have been the emphasis. But the trick with vaccine is that ASF is a fairly large virus and a complicated virus. So, what you really need is a bigger pot of money and more-focused effort to get a viable vaccine developed; that is such a large project,” Webb say, “Checkoff has a lot of good resources for research; a bigger pot and more coordinated long-term effort is needed.”
Faced with that reality, NPB’s Swine Health Committee is concentrating more on early detection.
Webb says the U.S. swine industry also needs to implement active surveillance for ASF and FMD, “meaning that there’s a lab in the background looking for it. We have a passive surveillance program where a producer who sees some pigs showing similar signs and calls a vet,” he says.
Getting oral fluids validated would be a big step toward supporting active surveillance of ASF and FMD, he says.
ASF, FMD and CSF all require heightened biosecurity. Producers can find information on the Secure Pork Supply website.
Producers are encouraged to visit the Pork Checkoff Store to get an FAD Push Pack. The kit includes foreign animal disease educational resources, including wall charts for FMD, CSF and ASF; visitor and employee biosecurity protocols; a report on ASF; and information on what to do in case a foreign animal disease is diagnosed in the United States.
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