By Andres Perez and Maria Sol Perez, University of Minnesota; Cristina Jurado and Jose Manuel Sanchez Vizcaino, Universidad Complutense de Madrid, Spain; Beatriz Martinez, University of California, Davis; and Lina Mur, Kansas State University
African swine fever is a disease caused by a virus that is not present in the United States, but that has been expanding extensively globally over the last few years. Clinical signs associated with ASF infection may vary from a subclinical form, with only unspecific signs of disease (such as fever) to high and sudden mortality rates. Despite the nature of the clinical signs, if the ASFv was introduced into the U.S., the industry will be deeply affected, including restrictions to movements and trade. For that reason, prevention is critical for the industry.
In 2018, ASF spread into Western Europe, and, for the first time, into China affecting 28 provinces and in early 2019 Mongolia and Vietnam reported their first outbreaks. Because the ASFv is highly resistant and because of such dramatic change in the global epidemiological conditions of ASF, there have been concerns the disease may continue to spread into disease-free regions, such as the U.S.
A study recently conducted by the University of Minnesota Center for Animal Health and Food Safety in collaboration with ASF experts from the Universidad Complutense de Madrid, Spain, and with funding provided by the National Pork Board and the Swine Health Information Center concluded that the risk for ASFv introduction into the U.S. via smuggling of pork in air passenger’s luggage has dramatically increased in 2018 and 2019, compared to previous years. Specifically, results suggest the mean risk of ASF virus introduction into the U.S. in this way has increased 183%, compared to the risk estimated before the disease spread into China, East Asia and Western Europe in 2018 and 2019.
Results also suggest it is likely (mean probability ~ 1) ASF virus is currently reaching U.S. airports in air passengers’ luggage, prior to customs inspection, which is consistent with the detection of ASF virus in seized pork in a number of Australian and Asian airports. Likely, the risk decreases substantially after customs inspection. Most of the risk (greater than 50%) was associated with flights originated from China and Hong Kong, followed by the Russian Federation (27%). Data showed risk was highest in summer and five airports (Newark, New Jersey; George Bush, Houston, Texas; Los Angeles, California; John F. Kennedy, New York; and San Jose, California) account for greater than 90% of the risk.
Prevention, and eventually early detection, are critical to mitigate the potential impact of an ASFv incursion into the U.S. High biosecurity levels are critical (because, for example, contact with individuals that may have traveled internationally, or with feral pigs that may have become infected with a hypothetical incursion may result in introduction of the virus into the farm). If you have, or anyone you know has, traveled international, remember not to bring pork products, report any potential contact you have had with swine farms overseas to the USDA upon return into the country at your port of entry and clean and disinfect clothes and material that traveled overseas.
Before you plan to visit a pig farm in the U.S., contact the herd veterinarian so that you can follow the appropriate downtime as you should not visit a pig farm right away. Likewise, any suspect of disease in the farm should be followed by consultation with your veterinarian and/or state animal health official and, if appropriate, with any of the 44 laboratories that are part of the National Animal Health Laboratory Network, that are able to test for ASF.