China marks one year with African swine fever
As fast as the virus spread across the world’s largest pork-producing country, the U.S. pork industry has worked twice as fast over the last 365 days to prevent and prepare for a potential outbreak.
It’s now been over a year since China’s Ministry of Agriculture and Rural Affairs confirmed its first African swine fever outbreak in Liaoning province. Twelve months later the country has had over 140 outbreaks in 32 provinces and regions and more than 1.16 million pigs have been culled in an effort to stop the spread of the disease in the Far East.
As fast as the virus spread across the world’s largest pork-producing country, the U.S. pork industry has worked twice as fast over the last 365 days to prevent and prepare for a potential outbreak on American soil. The National Pork Board, the National Pork Producers Council, the American Association of Swine Veterinarians, the Swine Health Information Center, the North American Meat Institute, the U.S. Meat Export Federation and the American Feed Industry Association have joined forces and to date, the coalition has completed more than 35 action items involving research, education, prevention and preparedness.
“I can't tell you in the last year how many producers and people outside the industry have asked me about the ASF situation in China,” says Liz Wagstrom, chief veterinarian of the National Pork Producers Council. “This provides an opportunity for us as an industry to promote our Secure Pork Supply program and biosecurity at pig shows. The U.S. pork industry wants to remain vigilant to prevent ASF from entering our borders or ports.”
Paul Sundberg, Swine Health Information Center executive director, says he’s also seen an impetus to collaborate more with government officials over the past year.
“In the last year, in my experience, there has been more cooperation and collaboration with the USDA about ASF that we have had in any other programs, maybe short of the pseudorabies eradication program back in the 1980s and 1990s,” Sundberg says. “That was an extraordinary amount of collaboration that would happen over a period of years. The collaboration and activity, all that both the industry and the USDA have done over the last year, is really an impressive amount and something that I think has absolutely helped in our prevention, preparedness and ability to respond. We don't know that we can guarantee we're going to keep it out, but we are way better than we were in August of last year.”
After reflecting on this past year with Wagstrom, Sundberg and several other pork executives, eight key action items stood out that the U.S. pork industry has implemented thus far since ASF broke in China, forever changing the way the industry will respond to and prevent any emerging or foreign animal disease from entering the U.S. swine herd.
Research
In just one short year, U.S. researchers have completed studies on feed/dust sampling methods and protocols, the validation of the extraction process for the detection of virus in feed and feed ingredients, feed additive mitigation, oral infectious doses in both liquids and feeds, disinfectants, epidemiology and diagnostics work as well as made proposals for further ASF-feed testing, diagnostics and vaccine.
While the science on viral transmission through feed and feedstuffs is still relatively young, it has yielded some useful information on mitigating the spread of costly viruses, such as ASF. One study has shown the theoretical ability for pathogenic swine viruses to survive transport to the United States in imported feedstuffs. Another one has shown the ability for ASF to infect pigs via feed and normal feeding activities.
A feedstuff can pose an animal health risk if it is not produced under biosecure conditions, if it is produced under unknown conditions or if it is not sealed to prevent post-processing contamination. This is where holding time offers an opportunity for viral contaminants to naturally degrade.
Wagstrom says that amount of industry research the U.S. has completed in such a short amount of time is extensive compared to other countries.
“Using Pork Checkoff funds, the Swine Health Information Center and the National Pork Board have financed a tremendous amount of very practical research – including issues such as disinfecting, risks from animal feed, looking at mitigations in animal feeds, looking at feed holding times and more,” Wagstrom says. “I don't know of other countries that are doing that level of research.”
Diagnostics
For Sundberg, one of the most foundational action items that has happened since August of last year, has been improved diagnostics. Prior to the ASF concerns in China, the only tissue that was approved by the USDA to test in any investigation was whole blood.
“There was nothing else as no other tissues were approved as an official ASF test, and diagnostically there just aren't samples of whole blood that come into the diagnostic lab as part of routine submission. They just don't do that,” Sundberg says. “That's a real problem with being able to find it quickly and that has expanded at a rate, that in my experience, was unprecedented with the cooperation of the USDA.”
Now in addition to whole blood, diagnostic labs are also permitted to do official ASF tests on spleen, tonsil and lymph node tissue samples.
The industry not only worked with the USDA, but also the National Animal Health Laboratory Network and National Veterinary Services Laboratories to promote the inclusion of a variety of tissues for submission for the diagnosis of ASF. Now in addition to whole blood, diagnostic labs are also permitted to do official ASF tests on spleen, tonsil and lymph node tissue samples.
“Prior to those efforts, whole blood was the only validated sample type that you could submit and get a positive diagnosis for African swine fever,” says Harry Snelson, DVM, American Association of Swine Veterinarians executive director. “Since then we've worked with USDA and the other groups to promote other tissues such as spleen, lymph nodes and those types of things to give veterinarians in the field a wider variety of tissue types that they might submit. The challenge is to try to focus those ASF diagnostic efforts on tissues that are more typically submitted during a normal diagnostic workup. Being able to detect, as early as possible, the introduction of a foreign animal disease is critically important.”
While spleen and lymph nodes submitted to diagnostic labs are two tissues that are routinely submitted, Sundberg says liver and lung tissue samples for example could also be further considerations as they are currently accepted in diagnostic laboratories in the European Union.
“Anything that we can do to broaden that list of tissues that are accepted officially would be important,” Sundberg says.
Surveillance
In addition to spleen, lymph nodes and tonsils being included in the official ASF testing, the tissue samples can also be tested for ASF, even if they were submitted as part of a routine submission under the USDA’s new ASF surveillance plan. The surveillance efforts conducted by the Animal and Plant Health Inspection Service now tests samples from high-risk animals, including sick pig submissions to veterinary diagnostic laboratories; sick or dead pigs at slaughter; and pigs from herds that are at greater risk for disease through such factors as exposure to feral swine or garbage feeding.
According to Snelson, the USDA had a surveillance program in place for classical swine fever for several years, but the one developed for ASF and foot-and-mouth disease had never actually been implemented.
“As African swine fever began to spread, we encouraged USDA to pull that off the shelf and make that a functional active program, which they have recently done,” Snelson says. “That has answered another spoke in that prevention and recognition wheel that we're all trying to address.”
Traditionally practitioners are very involved in preventing emerging and foreign animal diseases from entering the herd, however Snelson says AASV members have been much more active in state and regional response plans.
As Sundberg points out, the surveillance program ensures suspicious samples are being tested, regardless if a veterinarian suspected a FAD threat.