Cleanliness is next to sickiness. (You dirty rat…)

Even before I heard of the hygiene hypothesis, I knew that us hale and hearty types were going to eat a peck of dirt before we died.

I grew up in the era before there were different colored cutting boards and knives for each different food type. And while I did have food poisoning/stomach flu a couple of times, it was never because my mother didn’t bleach the kitchen after cutting up a chicken. One time, I was poisoned – along with hundreds of others – after eating Chicken a la King at a Christmas thank-you event held for everyone who worked for or volunteered at Our Lady of the Angels parish. (I was a worker: my friends and I had the very plum job of opening the donation envelopes, and counting and recording the collection take from all the Sunday masses. We got paid a couple of bucks, plus we got money for breakfast and junk food and were allowed to raffle off any Kennedy half-dollars that were thrown in the basket. As a side benefit, if all the priests were out, we could snoop around the rectory.)

I had the “stomach flu” a couple of times, too, the most memorable occasion being when some virulent virus went marauding through my college. The nurses went door to door distributing Lomotil – bring out your dead -  as we were all too sick to make it to the infirmary. Again, nothing to do with my mother’s neglecting to bleach the kitchen.

Throughout my life, I have pretty religiously followed the ten-second rule about food on the floor. I really don’t think there’s any salmonella lurking on my living room carpet. And, while I do wash fruits and veggies before I eat them, I have never felt the need to sterilize them.

And no one was wiping us down with special wipes, or dipping out mitts in Purell, every time we came in from our grubby play.

So here I am, on the cusp of old age, barely worse for the wear.

Anyway:

THE hygiene hypothesis posits that certain diseases—notably asthma, eczema and type-1 diabetes—which are becoming more common than they once were, are caused in part by modern environments being too clean. The diseases in question result from misfunctions of the immune system. The hygiene hypothesis suggests such misfunctions are the result of children’s immune systems being unable to learn, by appropriate exposure to viruses, bacteria, fungi and parasitic worms, how to respond properly. (Source: The Economist)

But the fetish for cleanliness in the house can’t hold a candle – a candle no doubt dripping waxen germs – to the sterility of a scientific lab. So now researchers are checking out an extension of the hygiene hypothesis, that: “laboratories’ spotlessness might also mean mice are sometimes too healthy to act as useful models for disease.”

Which isn’t such a good thing, “because mice are often used in medical experiments on the assumption that their reactions are similar enough to those of human beings for them to act as stand-ins.”

Mice acting as stand-ins for humans pretty much says it all. Of mice and me? No big difference? But better those little pink and white lab rats than a more sentient and human-like critter like a chimp or a dog.

So far, it’s not clear whether the hygiene hypothesis works with mice. Some studies say yes, another not so fast. As is often the case with these sorts of preliminary literature reviews, the outcome is a grab-bag of intriguing results, rather than a coherent hypothesis or prescription for action. But the evidence Dr [Lili] Tao and Dr [Tiffany] Reese have assembled suggests there is something going on here that needs investigating. It seems to be a classic example of the law of unintended consequences. The point of raising mice hygienically is to eliminate as many uncontrolled factors from an experiment as possible. That hygiene itself might be such a factor has not, until now, crossed people’s minds.

Now that it’s crossed the minds of at least a couple of scientists – and I do find it interesting that the scientists wondering about whether the lab is too clean are women – the next steps aren’t clear.

Running trials twice, with “dirty” and “clean” mice, could be one approach. Another might be to agree on a set of bugs to which early exposure is permitted.

We may see the day when you dirty rat is a good thing to have around the old lab.

Keep on experimenting, folks. Quite selfishly, whatever you discover via mice may prove useful to us aging Boomers. But I can tell you that the dirty mice will have more in common, hygiene-wise, with those of us who grew up before the world got so damned clean than those clean mice will.