Regulators suspect feed ingredient as a cause in deaths of millions of pigs, but lack concrete proof

Trying to find why a disease has killed millions of young pigs in 27 states, scientists and regulators are examining a wide variety of possible causes, including porcine plasma, "a widely used feed ingredient made from the blood of slaughtered hogs and fed to piglets," Jesse Newman reports for The Wall Street Journal. The virus, porcine epidemic diarrhea, is thought to have killed four million pigs, but actual numbers could be higher because deaths are reported voluntarily. (WSJ graphic)

"The number of new confirmed cases of the virus has accelerated recently, confounding farmers and veterinarians, who have ramped up their already stringent 'biosecurity' measures since last spring," Newman writes. "Those precautions include more aggressively disinfecting trucks and workers' boots and clothing when they enter and leave farms and barns."

The Food and Drug Administration, the Department of Agriculture and pork-industry officials "are examining a range of feed ingredients and manufacturing processes as well as other possible pathways for the virus, like contaminated air or dust particles carried from farm to farm," Newman writes. "Though the evidence is inconclusive, some researchers say that porcine plasma could be spreading the virus from adult pigs that show few symptoms, or that some plasma may have been contaminated in transit."

While come cases of PED are being linked to plasma, it's still not clear if feed is the cause of the illness, Newman writes. Greg Stevenson, a veterinary pathologist at Iowa State University who has studied the virus, told Newman, "Many people think that feed is the most likely suspect. But practically speaking, we have no proof." (Read more)