A British medical journal has published an article outlining the mysterious neurological illness that affected pork plant workers in 2007.
The article, published in Lancet Neurology, is the first comprehensive medical report of the disease that surfaced among nearly two dozen workers who processed pig brains at pork plants in Minnesota, Indiana and Nebraska, according to Mayo Clinic neurologist Daniel Lachance.
"We're quite clear that there have been no further cases, no new cases, since the middle of last year," Lachance said. "In fact, there have been no new cases with onset of symptoms from any time after the brain harvesting procedure was stopped."
The disease originated at the "head table," where workers would stick hoses with compressed air into pigs' skulls to blast out the brains. The pressurized air created an aerosol mist of pig brains.
“There have been no further cases, no new cases, since the middle of last year.”Mayo Clinic neurologist Daniel Lachance
Doctors at the Mayo Clinic, the Minnesota Department of Health and the Centers for Disease Control found that breathing in the brain matter prompted an auto-immune response in workers' bodies. That means their bodies began to attack the nerves in the arms and legs, and sometimes even the central nervous system.
In all, Mayo doctors treated 24 workers with the disease -- 21 from the Quality Pork Processors plant in Austin and three from a plant in Indiana. One workers was identified to have had the disease at a plant in Nebraska.
The range of symptoms varied from very mild, tingling numbness in the feet associated with aching and fatigue, to severe inflammation of the spinal cord, according to Lachance.
Most of the workers have shown signs of improvement in their physical exams and MRIs, and the majority of them have returned to work, Lachance said. Most are in light-duty jobs because they still have some discomfort with walking and standing. Lachance continues to monitor about 15 of the workers.
The three plants were the only ones investigators found in the U.S. that used compressed air to harvest pig brains, which are considered a delicacy in some Asian countries, and all have discontinued the practice.
"It's been an interesting experiment of nature," Lachance said. "It really highlighted the level of expertise and effort that went into this investigation to identify something new and unique, get in there, roll up their sleeves, (and) determine what this cause was."
Lachance said the problem probably never would have been identified and solved if it weren't for the patients' proximity to the Mayo Clinic.
"[It's] where we had the resources to unravel this and understand what was really going on," Lachance said.