Infectious ASF virus found in spray-dried porcine plasma used in pig feed in South Korea

A South Korean investigation has identified infectious African swine fever virus (ASFV) in spray-dried porcine plasma used as a feed ingredient. Experimental inoculation caused fatal ASF in pigs, and whole-genome sequencing linked the recovered virus closely to strains already circulating in South Korea. The findings add contaminated animal-derived feed ingredients to the list of potential ASF transmission pathways requiring tighter surveillance.

South Korea experienced an unusual increase in ASF during early 2026. By March, ASFV had been detected on 79 domestic pig farms, affecting about 345,000 pigs, including 24 farm outbreaks between January and March alone. Epidemiological investigations identified several possible routes, including wild boar exposure, illegal livestock products and contaminated feed.

Virus detected in plasma and compound feed

Researchers tested 72 spray-dried porcine plasma samples and 219 commercial compound-feed samples collected from affected farms. ASFV DNA was detected in two plasma samples on 19 February 2026 and in two compound-feed samples produced using plasma from the same batch five days later.

Nine 4-week-old pigs were then divided into three groups: three received ASFV-positive plasma by intramuscular inoculation, three were fed contaminated compound feed, and three served as controls. All three plasma-inoculated pigs developed fever and severe clinical signs and died after an average of eight days. Viremia and oral and rectal viral shedding were detectable from day four.

By contrast, pigs fed the contaminated compound feed remained uninfected during the 30-day experiment. The authors stress that this does not exclude oral transmission, because only three pigs were tested, infectivity may have declined during storage and oral infection generally requires a higher viral dose.

Genomics points to domestic Korean circulation

The recovered virus was genotype II, IGR type I. Whole-genome sequencing showed 99.98% nucleotide identity with ASFV/Korea/pig/Dangjin/2025, a virus previously detected during an outbreak in a South Korean pig farm. Phylogenetic analysis clustered the plasma-derived isolate with viruses circulating in South Korean domestic pigs and wild boar, suggesting emergence within the country rather than a recent independent introduction.

A feed-biosecurity issue

The interval between feed manufacture and associated farm outbreaks ranged from 56 to 116 days. ASFV can remain infectious for more than 100 days under refrigerated conditions, making long-term persistence in blood-derived ingredients biologically plausible.

The study does not prove that contaminated feed caused all, or even specific, 2026 outbreaks. But it demonstrates something epidemiologically important: infectious ASFV can survive in spray-dried porcine plasma and retain the capacity to cause lethal infection.

This strengthens the case for surveillance and risk controls covering porcine blood products, feed manufacturing and animal-derived feed ingredients, alongside established controls targeting wild boar, vehicles, people, pigs and pork products.