Workers fall ill after inhaling bits of pig brain

A new disease has surfaced in 12 people among the 1,300 employees at a factory run by Quality Pork Processors about 100 miles south of Minneapolis.

The ailment is characterized by sensations of burning, numbness and weakness in the arms and legs. For most, this is unpleasant but not disabling. For a few, however, the ailment has made walking difficult and work impossible. The symptoms have slowly lessened in severity, but in none of the sufferers have they disappeared completely.

While the illness is similar to some known conditions, it does not match any exactly. Nor is the leading theory of its cause something medical researchers have studied: The illness appears to be caused by inhaling microscopic flecks of pig brain.

"This appears to be something new," Minnesota's state epidemiologist, Ruth Lynfield, said last week.

The packing house, in Austin, Minn., slaughters 1,900 pigs a day, working two meat-cutting shifts and one clean-up shift. The 12 workers with the neurological illness -- most are Hispanic immigrants -- all work at or near the "head table" where the animals' severed heads are processed.

One of the steps in that part of the operation involves removing the pigs' brains with compressed air forced into the skull through the hole where the spinal cord enters. The brains are then packed and sent to markets in Korea and China as food.

Investigators say there is no reason to suspect that either the brains or the pork cuts were contaminated.

Their working hypothesis is that the harvesting technique -- known as "blowing brains" on the floor -- produces aerosols of brain matter. Once inhaled, the material prompts the immune system to produce antibodies that attack the pig brain compounds but apparently also attack the body's own nerve tissue.

If this theory is correct, the ailment, called "progressive inflammatory neuropathy," resembles Guillain-Barre syndrome, an autoimmune condition that sometimes follows fairly benign infections.

Although far from proved, the theory makes enough sense that the Centers for Disease Control and Prevention, in Atlanta, has cast a net to about 25 other large-scale pig slaughterhouses in 13 states, seeking other cases.

CDC investigators think they have found a few at a slaughterhouse in Indiana. Significantly, it is one of only two places other than the Minnesota packing plant that uses compressed air to empty pig skulls. All three have ceased that activity.

Weaker and weaker

Nearly a year passed between what is now recognized as the first case and the recent recognition of a "cluster."

In November 2006, a Hispanic man came down with fever, malaise and rapidly progressing weakness. By the time he was admitted to a hospital in Rochester, Minn. he could not walk. Weeks, or months before, he had been assigned the job of "blowing brains."

Like many of the subsequent patients, he had evidence in his bloodstream and spinal fluid of inflammation. He was given high-dose intravenous steroids, as is common for similar conditions. Over the course of a few months, he regained most of his function.

In April, he returned to work and the same job at the head table. Within two months, he developed the less dramatic symptoms seen in other patients: widespread pain and a sensation of weakness.

The plant management, the state health department and the local doctors are now casting a wide net to find other, older cases. A huge number of lab studies are also under way that are likely to shed light on the biological mechanisms of the illness. A harder question to answer may be: Why now?

Kelly Wadding, 55, started as a floor worker in 1970. He now owns and manages the company. He says it has been harvesting pig brains since 1998, using the same method and the same 70-pound pressure air hose.

Why the disease appeared now "is the million-dollar question," he said last week.