Researchers Identify Pork Plant Illness

May 29, 2008
Researchers recently identified the neurological illness that affected workers at several pork processing plants as immune-mediated polyradiculoneuropathy, or progressive inflammatory neuropathy, a disease of the peripheral nerves and spinal nerve roots.

Workers at Quality Pork Processors in Austin, Minn., first exhibited signs of illness in December 2006, and more workers developed symptoms in the following months. The workers experienced muscle weakness and numbness and an “abnormal sensation” in their muscles and legs. Additional cases associated with pork processing plant work also were reported in Indiana and Nebraska.

According to the Feb. 8 Morbidity and Mortality Weekly Report (MMWR), Minnesota Department of Health investigators interviewed workers at the Minnesota plant, where approximately 1,200 employees process 18,000 pigs per day. A total of 12 workers at this plant were affected by the illness by Jan. 28, 2008. It appears afflicted employees worked at the head table, where a compressed-air device is used to extract pig brains.

“In the process of blowing compressed air into the pig skull, brain material might have been splattered or even aerosolized, and workers might have been exposed through inhalation or contact with mucous membranes,” the MMWR report read.

A “Novel” Neurological Disorder

Researchers presented their findings and new information about the disease at the American Academy of Neurology’s 60th Anniversary Annual Meeting in April.

“This appears to be a new syndrome of immune-mediated polyradiculoneuropathy, or more simply, a novel neurological disorder caused by an immune system response to something in the workplace environment shared by these individuals,” said study author Daniel Lachance, M.D., of the Mayo Clinic in Rochester, Minn.

Electrodiagnostic tests showed that the patients had damage to the nerves at the root level, adjacent to the spinal cord, and at the farthest reaches of motor nerves, near the connection with muscle. Thirteen out of 15 patients had elevated protein levels in their brain and spinal cord fluid. Most patients had evidence of inflammation on spinal MRI examinations. All had evidence of activation of their immune systems. This was shown by a pattern of specific antibody production that has not been seen before.

For more on this illness, read Minnesota Pork Plant Workers Afflicted With Mysterious Illness.

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