A 13th meatpacker in Austin appears to have the same neurological symptoms identified in 12 others who sparked a nationwide disease investigation in December.

But unlike the others, this worker was not stationed near the high-powered air compressor system used to remove pig brain tissue at Quality Pork Processors (QPP) that has linked the other 12 workers.

However, the 13th employee was exposed to brain tissue in the rendering operation in the basement of the sprawling plant QPP shares with Hormel Foods.

QPP employs 1,300 workers and slaughters pigs on one side of the building. On the other side, an estimated 1,400 Hormel workers process the meat into bacon and other products. Hormel owns the rendering operation.

The first 12 cases of the disease involved employees working at the "head table" of QPP, which was spun off from Hormel in 1989. QPP halted the process of blowing out brains with the air compression system as soon as the investigation began.

As a result of the most recent suspected case, health officials are expanding the investigation to include Hormel workers in and around the rendering operation, according to a notice to employees posted in the plant Tuesday.

The meatpackers in Austin and two at a plant in Indiana have reported fatigue, numbness and tingling in their arms and legs, with a wide range in severity. A few are severely disabled, while others have been treated and returned to work.

State and federal health officials are looking into whether pig brain tissue, liquefied during removal by the air-compression system and sprayed into the air as droplets, somehow caused nerve damage in workers who were exposed to it. The brains are frozen in boxes, and shipped to the southern United States and Asia, where they are sold as food.

Investigators theorize that a protein or other substance from the animal brains triggered the workers' immune systems into mistakenly attacking their own nerve tissue. If that proves to be the case, then they will have identified a new syndrome, one they have named progressive inflammatory neuropathy (PIN).

Union officials said that after the brains are removed at the QPP head table, the pig heads are dropped down a chute to the rendering department in the basement of the plant, where they could still spatter tissue into the air when they land. That is where the 13th worker was stationed.

Minnesota state epidemiologist Ruth Lynfield, who is in charge of the investigation, said "We are investigating a likely additional case." She said that the worker had exposure to brain tissue and that the department is investigating other potential cases as well. Disease investigators will be at the Hormel plant today interviewing workers in the rendering area, she said.

Last week, state officials said they were broadening the investigation of the QPP section of the plant to thousands of former meat packers going back a decade, to when the powerful air-compression system was first installed.

Josephine Marcotty • 612-673-7394