"Hygiene hypothesis" suggests hypercleanliness causing more sickness.

The Washington Post (3/26, Telis, 489K) reports, "A growing body of evidence suggests that all the antibacterial-wiping, germ-killing cleanliness of the developed world may actually be making us more prone to getting sick - and that a little more dirt might help us stay healthier in the long run." The "hygiene hypothesis" idea "has been cited as a possible explanation for everything from multiple sclerosis to hay fever and autism." Michael Zasloff, an immunologist and physician at MedStar Georgetown University Hospital, commented, "Bacteria, fungi, lots of these things we think of as bad - they're all part of our environment, and we evolved to live with them." He explained that "through exposure to these microbes early in life, your immune system learns what's harmful and what isn't...and that readies the immune responses you'll have for the rest of your life."