Mr. Clean Is Sick

Do you get sick too easily?  Did you grow up with allergies?  One reason might be your home environment is too clean, says a story on PhysOrg.
    The “hygiene hypothesis” asserts that our immune system over-reacts to lack of stimulation by turning on itself – producing autoimmune diseases and allergies.  It “blames increased allergies on cleaner homes, increased air pollution and changes in diet.  Obesity and lack of exercise may also play a role.”
    One researcher at University of Iowa is treating patients with multiple sclerosis and colitis with parasitic worms.  He claims incidents of these autoimmune diseases increased when parasitic worms were eliminated from our environment.  He thinks they have a “profound symbiotic effect on developing and maintaining the immune system.”

Not sure we are ready to go that far and add parasitic worms to the diet – that idea needs much more proof!  The principle in this article could, however, help us think differently about some organisms with bad reputations.  Remember the milk maidens in Robert Jenner’s day who developed immunity to smallpox by working around cows?  Humans apparently need exposure to certain organisms to develop and maintain the immune system.  Certain tribes in Africa seem to get along quite well living in harmony with their livestock outdoors in environments that would freak out an American city dweller.
    Maybe we should stop thinking of parasites as good vs evil, and view them instead as accelerators and brakes.  Everything in the living world is in motion.  There are constant pushes and pulls.  This is true in the genetic world, where promoters and repressors steer the expression of genes in a complex dance.  Our immune systems are not going to sit idly by when everything is sterile.  Needing stimulation and direction, they will practice on the body’s own cells, like bored firefighters setting the fire station on fire.  What’s needed in this view is balance, not isolation.
    Our bodies are already covered inside and out with bacteria and other organisms, so encounters with more of them is only a matter of degree.  The microorganisms, fungi and worms in a new environment may act as alarms to keep our bodies ready.  Perhaps they even inject information needed for the body to adapt to the new environment.  They only become problematic when they swamp the body’s ability to react – perhaps because the immune response was not adequately exercised during development.  Allergies, in this view, are an over-reaction to things that should have been encountered in childhood.
    These are mere suggestions that need more rigorous investigation.  The hygiene hypothesis cannot explain everything.  Plagues often ravage tribes close to nature as much as they do city dwellers.  Some parasites are nasty in any environment.  Maybe some of them had a useful function once but mutated into pathogens.  Whatever the balance point, cleanliness is still virtuous.  Didn’t we learn that from Joseph Lister?  (See last month’s Scientist of the Month).  All good suggestions need moderation.  Continue to shower and wash your hands.
    The idea humans need exposure to organisms in natural environments makes sense, though.  Would some hospital patients recover faster in gardens open to fresh air?  Would incidence of allergies drop with more exposure to nature in childhood?  Is working the earth in gardening and farming good for health?  These seem like proper subjects for controlled experimentation and long-term population studies.  Meanwhile, it’s a good bet to increase your outdoor exposure.  Jog outdoors when you can instead of going to the gym.  Take your kids camping; go on hikes and visit a variety of outdoor environments.  This is unquestionably a better strategy for long-term health than parking them in front of the TV or video games with a bag of junk food.  This is a one principle both creationists and evolutionists should be able to agree on.