From November 2006 to May 2008, a mysterious illnesses involving some pork processing  plant workers in Minnesota and Indiana had officials scrambling for answers. Now a report in the medical journal, Lancet Neurology, has confirmed that the illnesses were caused by an autoimmune response to a mist of pig brain tissue.
The study looked at the outbreak and response from the Mayo Clinic, the Minnesota Health Department and the Centers for Disease Control and Prevention. In its assessment, the report noted that patients in Minnesota reported symptoms within weeks of an increase in line speed that occurred in 2006. All the ill workers worked in or near areas where compressed air was used to extract pig brains.

Researchers also found that the extent to which workers got sick was influenced by their work station location-- the closer to the extraction, the more likely they would be affected.

The study does not detail the exact biological mechanism of the disease, which researchers said might never be known.

The 24 affected workers, who worked at Quality Pork Processors in Austin, Minn., and an unnamed plant in Delphi, Ind., are all improving, and most no longer have measurable symptoms. Both processing plants have stopped removing brains using compressed air.

You can read the full Lancet article at its Web site.