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The Case of the Curious Disease

Three years ago, when a strange illness surfaced among workers at an Austin slaughterhouse, state health investigators and researchers from the Mayo Clinic stepped in to search for the cause. Their sleuthing not only got workers back on the job, it also resulted in the discovery of a new disease.

The Case of the Curious Disease
Photo by Jonathan Chapman

(page 3 of 4)

Roughly 30 people were working at stations around the 16-by-20-foot head table. Those workers tasked with “blowing brains” would, in rapid succession, insert severed pig heads into a device that pneumatically blasted the brains out of the skull—each blast sending up a mist of brain matter into the surrounding air. Many pork processors simply split the skull with a large knife or a band saw, but QPP had installed this system nearly 10 years before because, according to Wadding, it was “more efficient and easier on the worker.” It was also, presumably, safer than using knives.

But the mist hanging in the air around the head table alarmed Lynfield and her colleagues. “I said, ‘What should we do about Animal Health about the disease. Two such plants surfaced: one in Nebraska, where one employee was sick, and the other in Indiana, with seven ailing workers. Of the 26 plants canvassed in the United States, the Nebraska and Indiana operations were the only others that removed brains with compressed air. On December 3, 2007, Lynfield held a press conference in Austin to announce that the illness was likely an inflammatory neurological disease and that it probably was related to removing brains from hogs’ heads with compressed air. They had found the source of the problem in little more than a month’s span, yet the cause remained a mystery. How could pigs’ brains actually cause such an illness? this?’ ” she recalls. Wadding immediately ordered a halt to the brain-blowing process. “It was easy,” he says, in retrospect, “to take the brains out of the mix.” The company simply stopped selling the organs.

When brain blowing ended, so did new occurrences of the disease. Lynfield and her team seemed to have found the root of the problem: Statistical analysis later showed that those individuals who worked 10 feet or less from the brain-removal device were 14 times more likely to have the disease than those who worked farther away. Hoping to identify workers with similar problems at other pork-processing plants, the investigators alerted the World Health Organization and the World Organization for Animal Health about the disease. Two such plants surfaced: one in Nebraska, where one employee was sick, and the other in Indiana, with seven ailing workers. Of the 26 plants canvassed in the United States, the Nebraska and Indiana operations were the only others that removed brains with compressed air.

On December 3, 2007, Lynfield held a press conference in Austin to announce that the illness was likely an inflammatory neurological disease and that it probably was related to removing brains from hogs’ heads with compressed air. They had found the source of the problem in little more than a month’s span, yet the cause remained a mystery. How could pigs’ brains actually cause such an illness?


IT FELL TO LACHANCE and his colleagues at the Mayo Clinic to treat the patients with the disease and assess its pathology. From the international dragnet, a total of 29 people had been found to have the illness—the seven in Indiana, the one in Nebraska, and 21 in Minnesota, all at QPP. By April 2008, Lachance and his colleague P. James B. Dyck, MD, a peripheral neuropathy expert, had subjected most of the a ected QPP workers to a battery of procedures, including MRI scans, blood tests, electrodiagnostic studies, and cerebrospinal-fl uid exams.

For a scientist, the case was a strange and exciting puzzle. “We all realized,” Lachance says, “that this was something that was really quite novel, something that had never been seen before, at least not in the modern era, that we were aware of.”

The working theory was that pig brains in a fine mist had somehow entered the bloodstream—most likely via the respiratory system. The tests and subsequent research seemed to rule out any type of infectious disease. The most likely cause of the illness, Lachance and his colleagues posited, must be an autoimmune response—the body’s defense system was, for some strange reason, attacking itself.

The human immune system identifies harmful invaders (called antigens) by their unique protein sequences and then produces antibodies that bind themselves to and destroy the antigens. If bacteria enter the body through a cut, for example, the body identifies them as foreign and possibly harmful and then releases antibodies to attack and destroy them. Sometimes, however, molecular similarities exist between antigens and healthy tissue, causing an immunologic overreaction in which the antibodies attack not only the antigens but also any healthy cells that might resemble the antigen. Scientists call this “molecular mimicry,” and it’s one of the leading theories explaining why the immune system turns on its own body in diseases such as multiple sclerosis, rheumatoid arthritis, lupus, and type 1 diabetes.


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