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.
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Genetically speaking, pigs and humans are very similar (that’s one reason doctors can transplant porcine heart valves in humans). Lachance theorized that the sick slaughterhouse employees had somehow absorbed aerosolized pig-brain tissue through their lungs or via small cuts, and the resulting immune responses targeted not only the foreign substance but, in a case of mistaken identity, the workers’ own healthy nerve tissues as well.
This wasn’t the first instance in which scientists had found that animal neural tissue could triggered an autoimmune attack on the human nervous system. In 1885, Louis Pasteur and Émile Roux developed the first vaccine for rabies, created by harvesting the virus from the nerve tissues of rabies-infected rabbits. Pharmaceutical manufacturers now use different methods, but that early vaccine brought with it a wide range of possible side effects, including the demyelination of the central or peripheral nervous system. Such damage to the myelin sheath, which covers nerve fibers like insulation on an electrical wire, can result in neurological dysfunction, cognitive problems, and even coma.
Hoping to confirm the autoimmune diagnosis, Lachance conducted a handful of tests. One indicated inflammation of nerve roots and the meninges, the membranes that covers the brain and spinal cord. Nerve biopsies showed inflammation, demyelination, and nerve-fiber degeneration. And a final package of antibody tests developed at the Mayo Clinic confirmed Lachance’s belief that the antibodies were specifically targeting the nervous system. The combined picture that resulted from all of the tests proved the discovery of an autoimmune disease that had never been reported anywhere else in the world. Lachance and his colleagues ultimately called it “sensory predominant polyradiculoneuropathy.”
Yet in science, unlike in the detective world, a case is never completely closed. Discoveries and solutions lead to further questions that may never be answered. For example, some workers in the QPP control group tested positive for the antibody yet remained healthy. Why? Lachance says that workers’ proximity to the brainblowing device was key. Though many were exposed, only those closest to the process became ill.
And given that QPP had been blowing brains for 10 years, why didn’t the illness crop up sooner? Some workers suggest that the problems appeared in greater numbers after changes were made in the processing operations. But, says the CDC’s Stacy Holzbauer, “Because there were so many variables—different workers of different heights, a fan on or off, for example—we can’t prove or disprove that theory without setting up a controlled test. And we never want to reproduce that problem again.”
“It was an interesting experiment of nature,” says Lachance. “It’s unlike anything I’ll ever experience again in my career.” Yet what investigators learned may also someday help advance new research into autoimmune diseases or assist doctors in understanding neurological disorders. “Science evolves over time in unexpected ways,” Lachance says.
But for the QPP workers who fell ill, the most important piece has been getting their health and jobs back. To various degrees, all of the people who fell victim to the mysterious disorder have recovered. “Most people are working again,” says the union’s Richard Morgan, though not all are at full capacity. He adds, “Hats off to the folks who put the pieces of this nasty little puzzle together.”