By Jeff Hansel
jhansel@postbulletin.com
Investigators studying a cluster of neurological slaughterhouse illnesses in Austin say there’s now a way to definitively tell whether someone has been exposed.
Also, more cases of progressive inflammatory neuropathy have been identified. Eighteen patients have been confirmed at Mayo Clinic, said Dr. Jim Sejvar, a neuroepidemiologist with the Centers for Disease Control and Prevention. Two additional cases were identified from 2004 and 2005, making a total of 20, he said.
Researchers first learned about illnesses at Quality Pork Processors in Austin. Now they’re looking more intensely at people who worked at Indiana Packers Corporation in Delphi, Ind. and Hormel Foods Corporation in Fremont, Neb., where a few illnesses have been found.
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"There do appear to be cases associated with these other plants," Sejvar said. Those were the only three plants nationwide that used high-pressure air to harvest brain tissue from pigs, a process now suspected to be associated with the illness. That process was discontinued once the illnesses were recognized.
Dr. Daniel Lachance, a Mayo Clinic neurologist from Rochester, spoke Wednesday at the annual meeting of the American Academy of Neurology, with a goal of raising awareness among specialists.
LaChance said the common thread among the affected workers is that they all worked in a part of the plants that used compressed air to blow pig brains out of skulls. The working hypothesis, he told reporters, is still that some of the brain tissue was turned into a fine mist during the process, the workers became exposed to it and somehow developed an autoimmune response that caused nerve damage.
Test detects patterns
Researchers now say that most affected patients experience pain, tingling or numbness as the predominant symptoms, rather than serious immobility.
"We really have not had a forum to present our findings to our peers," Lachance said.
He said an "immunofluorescence assay" uses a patient’s blood serum placed on mouse tissue. Then, an antibody gets "tagged" with the dye called fluorazine.
A special microscope detects patterns when the human antibody binds. Mayo has been using the test for 30 years, but has never seen the pattern shown by people exposed to PIN.
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"We have a new immunofluorescence pattern in a well-defined group of patients who all work at the same place," Lachance said.
That means Mayo can now tell if someone has been exposed to PIN.
"The assay doesn’t allow us to identify what the antibodies are responding to. But at least it allows you to screen," Lachance said.
That doesn’t mean the test can be used to diagnose yet.
"We know that the cases have the pattern," he said. "But we don’t know how many people have the pattern, but don’t have the disease. If the patient does not have the antibody, they may not have the disease — but we’re not completely sure of that yet."
Researchers are checking whether any workers show the pattern but don’t have symptoms.
"That study is ongoing and it’s being done in cooperation with the Minnesota Department of Health," Lachance said. No cause has been proved.
"All we know is associations. And while associations are clues, they don’t specify a true cause," Lachance said.
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Said Sejvar, "The work that the Mayo Clinic is doing is very groundbreaking, and has yielded very interesting preliminary results. In addition, there are a number of ongoing collaborations with a number of academic institutions to further define the illness."
The Associated Press contributed to this article.
Researchers still don’t think the general public is at risk.
Even if the illness turns out to be an isolated problem, Lachance said he’s hopeful that researchers will be able to apply what they’ve learned from it to other autoimmune illnesses. Scientists still don’t know what triggers many of them, he said.
"It doesn’t appear that the slaughtered pigs have been ill," Sejvar said. "It doesn’t appear that this is in any way a foodborne illness. And it doesn’t appear as if this particular illness can be transmitted person to person."
The Associated Press contributed to this article.
