04 December 2007

Gross job leads to rare disease

Pork plant employees contract neurological illness

Between December last year and July of this year 11 workers at a pork processing plant in Austin, MN have been victims of a strange set of symptoms. Numbness and tingling in their hands. At first I'm sure they thought it was some repetitive stress, but the Health Department is saying that it is Chronic Inflammatory Demyelinating Polyneuropathy.

Department investigators have been poring over the cases since then. So far they say they have determined that the workers experienced an inflammatory response to some kind of trigger. But they haven't identified the trigger yet. It could be an infectious agent within the plant, or even a chemical exposure.

Well, lets look at what CIDP is. Whats happening is that something, the Health Department doesn't know what, is triggering an immune response that is targeting the myelin sheath that is wrapped around the dendrite of the nerve cell.

The Schwann cells make up the myelin sheath, the gaps between them are nodes of Ranvier. This set up allows the electrochemical impulse to travel down the axon more efficiently than an unmyelinated axon. Human neurons need this myelination, when those Schwann cells are damaged, the message from the nerve cell doesn't travel as it should, leading to the weakness, numbness and tingling. See Wikipedia.

So the next question is what would make the immune system target the Schwan cells that create the myelin sheath? The Health Department doesn't know right now. Since all the workers suffering were using compressed air to remove the brain from the pig heads, most people are going to think of a prion disease. But this is not much like prion diseases that tend to attack the central nervous system rather that the peripheral. Plus, there are not any known prion diseases in pigs. That isn't to say it isn't possible that there is a mad pig disease, just that we have no documentation of anything that would fit that description.

I'm going to reference the Star Tribune now, since its physical newspaper thats in front of me, but I don't like to use their online stuff since they require registration after a few clicks.

Anyway, the paper says that the workers are different ages, ethnicities, and genders. This means that it really is something at work and probably not the water. Add to that the fact that no one not working with the brains has come down with this. So there is something about either the brains or the way they were removing the brains.

"We've already given some of our employees a face mask, and discontinued some operations that could be potential. Again, we have no idea of the cause," said Wadding. "But we do want to take every precautionary step that the Department of Health recommends, and that we see that could possibly contribute to this."

The Strib dead tree edition also says the company is no longer using compressed air, and is now giving out safety goggles, disposable sleeves and towels for showers. You mean that the workers were using compressed air, shooting brain matter all over, and they didn't have goggles, face masks, or sleeves? Besides the immediate eeww factor, I don't think its a good idea to be aerosolizing raw biological tissue at all, much less without eye protection.

However, there is still a chance that the root cause of this CIDP is chemical rather than biological. I don't know enough about how one cleans a pork slaughtering plant to speculate on the cleaning agents. Might they have used a different chemical for cleaning the debraining room? Might the compressed air lines have been cleaned by some nasty chemical?

On top of all this, the plant has a strange history. The plant was spun off from Hormell in 1989. According to my father, whom I don't think counts as a scholarly reference, this lead to a strike because the spin off meant it was suddenly a non-union shop. Anyone who wasn't four at the time, as I was, want to confirm that? Maybe its my pro-union bias, but I worry about safe working conditions at non-union companies.

I hope the workers get better.

EDIT: It seems that CIPD has been ruled out, see more here.


Al said...

My heart goes out to all these folks, treating CIDP can be quite expensive. On the bright side, this is a fantastic opportunity for medical sleuths to focus on this disease and maybe shed a little light on its causes.

E.M. said...

Thanks for the comment. I think its going to put some focus on CIDP & Guillian-Barré and the connection to pigs.