African swine fever (ASF) is like a recurring nightmare that won’t get out of your head. You can’t sleep at night and you can’t stop thinking about it during the day, because should the virus enter the U.S., your future as a pork producer would radically change. The disease was first described in 1921, but until 2007 it was primarily contained to sub-Sahara Africa and Sardinia, says Andres Perez, DVM, the Endowed Chair of Global Animal Health and Food Safety, Director, Center for Animal Health and Food Safety, at the University of Minnesota. At last year’s U.S. Animal Health Association (USAHA) annual meeting, he explained that movement of ASF across Eastern Europe took place from 2007 to 2016, and then the virus found new borders. In the last several years, the ASF virus has been identified in more than 50 countries that encompass 75% of all the pigs in the world. Discussions on ASF will continue at this year’s USAHA meeting, to be held October 24-30, 2019 in Providence, Rhode Island.
While the disease does not have human health implications, it has turned the global pork industry on its head, with major pork shortages in China and Southeast Asia. U.S. Customs and Border Patrol officials have ramped up efforts to keep ASF from entering the country, and U.S. producers are focused on biosecurity efforts to keep ASF – or any other foreign animal disease – from entering their herds.
Much has been written about ASF, but here are five things you may not know:
1. The spread continues: According to the Food and Agriculture Organization of the United Nations (FAO), the Veterinary Bureau in China released statistics last week showing a 38.7% decrease in the number of live pigs and a 37.4% decrease in the number of breeding sows in China for August 2019 over the same period last year. Many observers of the situation in China believe the actual numbers to be much higher. The FAO also reported that within the last month, ASF has spread to new locations in Vietnam, North and South Korea, Lao PDR, Cambodia and The Philippines.
2. ASF is complex: The virus displays a variety of clinical signs in infected pigs, from peracute (sudden death within 1 to 4 days), acute (death within 3 to 8 days), and of great concern is the subacute, chronic or subclinical forms of the virus, primarily in endemic areas. It is a large virus with a complex molecular structure and high genetic variability (24 genotypes), says Jose Manuel Sanchez-Vizcaino, an expert on ASF from the University Complutense of Madrid. The National Institute of Health says, “African swine fever is a double-stranded DNA genome that varies in length from about 170 to 193 kbp [kilo-base pair, a unit measurement of DNA or RNA length, equal to 1,000 base pairs], depending on the isolate. It contains between 150 and 167 open reading frames that are closely spaced and read from both DNA strands.” The virus also is very resistant to the environment, Sanchez-Vizcaino says.
3. Transportation and trade are primary pathways: The transportation and trade of infected pigs and contaminated pork products are the primary transmission mechanisms, says Perez. “Farmers tend to sell their pigs as soon as ASF is detected in an area because indemnities are insufficient,” he says. “That’s why we’ve seen such widespread distribution of the disease.” More than 70% of the spread has been from contaminated vehicles, Perez added.
4. Feed risks continue: U.S. producers must be cautious with imported feed and feed ingredients, and follow safe storage times, Paul Sundberg, director of the Swine Health Information Center, reported at the 2018 USAHA meeting. “We’re looking for new ways to validate feed with Kansas State University by using dust samples from feed ingredients,” he says. “We want to make sure whatever we receive has been handled properly because [China] is positive for a lot of things that we don’t want.” Updates from several studies on feed risk will be presented at the upcoming USAHA meeting.
5. Wild pigs a problem: The wild boar population in Europe has risen dramatically in recent years, which poses a major problem for countries in close proximity, says Sanchez-Vizcaino. “Not only do we have infected animals, we have biological vectors: Pay attention to wild boar – in the EU they’re a big problem. In the future, there will be more breaks because of the increase in this population.” Even when wild boars are killed, the remaining blood can infect animals. “A single drop of blood can have more than 300 million copies of the virus,” Sanchez-Vizcaino says. It’s something for U.S. officials to think about as well, as the wild pig population in this country continues to migrate north.
Producers can’t become complacent about biosecurity, and should immediately report any clinical signs in their animals that look unusual.
“We’ve told producers – don’t assume that you know what’s happening in your herd,” Sundberg points out. “Talk to your veterinarian – make them a partner in your herd’s health.”
Editor’s note: To hear more updates on animal welfare, foreign animal diseases and much more, plan to attend the USAHA Annual Meeting, to take place on October 24-30, 2019 in Providence, Rhode Island. For more information, go to: https://www.usaha.org/2019-annual-meeting.