A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
We detected African swine fever virus DNA in feed and spray-dried porcine plasma (SDPP) used as a feed ingredient in South Korea. Pigs inoculated with SDPP developed fatal infection. An isolate phylogenetically clustered with South Korea strains. Our findings highlight the need for strengthened risk management of animal-derived feed ingredients like SDPP.
African swine fever (ASF), caused by ASF virus (ASFV), is a highly contagious and fatal hemorrhagic disease of domestic pigs and wild boars across Eurasia ( 1 ). In Africa, soft ticks ( Ornithodoros spp.) act as biological vectors, whereas wild suids serve as asymptomatic reservoirs ( 2 ). In Eurasia, ASFV is primarily maintained and spread by wild boars, although transmission also occurs through contaminated pork products and swill feeding ( 3 , 4 ). Because of its environmental stability, ASFV remains infectious in meat and blood for weeks to months ( 5 ). Since its introduction from Africa into the country of Georgia in 2007 ( 6 ), ASFV has spread throughout Eastern Europe and Russia and subsequently into Asia ( 4 , 6 ). ASFV outbreaks were reported in China in 2018 and Mongolia in early 2019; rapid spread across Asia followed ( 4 , 6 ).
In South Korea, after the first outbreak in Paju in 2019 ( 6 ), ASFV had been detected in 79 domestic pig farms by March 2026, affecting ≈345,000 pigs ( 7 ). Before 2026, ASF outbreaks on domestic pig farms in South Korea occurred sporadically, and only a small number of outbreaks were reported each year. However, an unprecedented number of outbreaks occurred during January–March 2026, affecting 24 domestic pig farms. Epidemiologic investigations linked some affected farms to ASFV DNA–positive feed, whereas other farms had potential risk factors such as wild boar exposure and illegal livestock products ( 8 ). The investigations detected ASFV DNA in commercial compound feed (CF) and in spray-dried porcine plasma (SDPP), which is produced from slaughterhouse blood and used as a feed ingredient because of its high nutritional value and beneficial effects on growth ( 9 ). The ASFV DNA–positive CF was produced by a feed manufacturer using SDPP from the same batch as the ASFV DNA–positive SDPP. We experimentally administered ASFV DNA–positive SDPP and CF samples to pigs to determine if the compounds could cause disease and genetically characterized the virus to identify its origin.
We tested SDPP (n = 72) and CF (n = 219) samples collected from ASF outbreak pig farms in South Korea for ASFV at the Animal and Plant Quarantine Agency (Gimcheon, South Korea). In brief, we suspended 5 g of each sample in phosphate-buffered saline (PBS) for DNA extraction and real-time PCR. On February 19, 2026, we detected ASFV DNA in 2 SDPP samples (cycle threshold [Ct] values 28.48 and 31.18). On February 24, 2026, we also detected ASFV DNA in 2 commercial CFs produced using SDPP and stored at a pig farm (Ct values 35.97 and 37.71) ( Appendix Table 1). However, virus isolation using primary porcine alveolar macrophages, as previously described ( 10 ), was unsuccessful.
For the experiment, we used 9 healthy 4-week-old Landrace pigs from a co…