Progressive inflammatory neuropathy

Progressive inflammatory neuropathy (PIN) is a disease that was identified in a report, released on January 31, 2008, by the Centers for Disease Control and Prevention. The first known outbreak of this neuropathy occurred in southeastern Minnesota in the United States. The disease was reported among pig slaughterhouse workers who appeared at various care facilities in the area reporting similar neurological symptoms. The disease was later identified at pork processing plants in Indiana and Nebraska as well. The condition is characterized by acute paralysis, pain, fatigue, numbness, and weakness, especially in extremities. It was initially believed that workers might have contracted the disease through inhaling aerosols from pig brains blown through a compressed-air hose and that this exposure to pig neural tissue induced an autoimmune response that might have produced their mysterious peripheral neuropathy. These suspicions were confirmed in reports and investigations conducted at the Mayo Clinic in Rochester, Minnesota.

An initial comprehensive study of 24 known cases was conducted by multiple doctors from various disciplines at the Mayo Clinic. They identified the cause of this neurological disease to be occupational exposure to aerosolized pig neural tissue. Investigators from the Minnesota Department of Health (MDH) simultaneously determined that the 70 ppsi pressure used to liquefy and extract the pig brains caused the aerosolization of the pig neural tissue, sending it into the air in a fine mist. The workers closest in proximity to the "head" table, the area in the plant where high pressured air was used to evacuate the brain tissue from the pig's skull, were the most likely to be affected. The aerosolized mist was inhaled and readily absorbed into the workers' mucus membranes. The pig neural tissue was recognized by their systems as foreign and an immune response was initiated. The pig antigen was found most prominently in the nerve roots of the spine which were also swollen. Researchers determined that the irritation was due to the voltage-gated potassium channels being blocked. They identified 125 1-α-dendrotoxin as the antagonist that binds to and blocks the channels, causing an intracellular build-up of potassium ions which causes inflammation and irritation, and consequently, hyper-excitability in the peripheral nervous system. It is this hyper-excitability that leads to the tingling, numbness, pain, and weakness.

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