MINNEAPOLIS (AP) — Investigators are closer to understanding a mysterious illness reported by pork plant workers in Minnesota and Indiana and now have pinned a name on it, officials said.
The Centers for Disease Control and Prevention issued a report Thursday summarizing the investigation so far that gives the condition a name — progressive inflammatory neuropathy.
Minnesota officials said they were broadening their investigation to thousands of former employees at the Quality Pork Processors Inc. plant in Austin, going back a decade to when a powerful compressed air system was installed to remove brain tissue from pig heads.
Investigators have been trying to determine whether pig brain tissue, sprayed into the air as droplets during removal by the compressed air system, was inhaled by workers and made them sick.
If further investigation proves their theories true, they will have identified a rare, new condition that could shed light on a whole family of poorly understood disorders in which the body's immune system attacks the nerves or the sheath that surrounds them, the Star Tribune reported.
This ''could have far reaching applications in terms of our understanding of the mechanism of disease,'' said Ruth Lynfield, Minnesota's state epidemiologist, who is heading the investigation here.
Since December, 12 meatpackers in Austin and two at a plant in Indiana have reported fatigue, numbness and tingling in their arms and legs. A few are severely disabled; others have returned to work.
Indiana health officials have declined to discuss the conditions of the affected workers there or say where they were employed, citing patient privacy laws.
All 14 employees worked near powerful compressed air systems that blow brains out of pig heads at what is known as the head table. Both plants have stopped using the process.
A plant in Nebraska had also been using the compressed-air process to remove the pig brains, but the CDC said Thursday that no cases of the illness had been linked to the Nebraska plant. That plant also stopped using the process earlier this month after Minnesota health officials raised concerns.
Lynfield said investigators are now looking for anyone who has worked near Quality Pork's head table since 1997. That's difficult because the plant employs about 1,200 workers, many of them immigrants, and turnover is high.
''But we feel it's important to look for prior cases,'' she said.
Investigators say they've ruled out toxins as a cause, and viruses or bacteria are unlikely because none of the affected workers reported infectious disease symptoms, such as fever, before the onset of their neurological symptoms. That would leave the brain tissue itself.
Experts said the foreign pig tissue may have triggered the workers' immune system, which then attacked their own neural tissue.
Imaging tests show that many of the affected workers have inflammation in the nerve roots in the bottom half of their spinal cords, said Dr. Daniel Lachance, the Mayo Clinic neurologist who first recognized the cluster of unusual cases.
Experts at the Mayo Clinic and New York's Columbia University are now trying to devise ways to test pig brain tissue against the immune cells of the sick workers, Lynfield said. It could be months before results are in, she said.