National Post

Discerning germs: ‘Hygiene hypothesis’ favours exposure over manic cleanliness
Years ago, parents would tell kids to use their hands to cover their mouths when they coughed. Then those children would use the same hand to touch subway poles, escalator railings or door handles, transmitting the germs they just coughed out. Then came “sleeve sneeze” public health campaigns. So far as I can tell through media database searches, Toronto’s began in 2006, amid increasing concerns about the pandemic flu. Whenever it started, the “sleeve sneeze” campaign must be one of the great public health victories of the early 21st century: Everyone seems to use it.

I do wonder, however, whether we’re all becoming a bit too paranoid about germs. I include my own family in this group. Once we left the doctors’ office, for example, my wife and I encouraged our children to use a hand sanitizer. When our kids were toddlers our house had alcohol wipes and Purell vials all over the place. But is all this washing and disinfecting really necessary? Is it proactive prevention? Or overly paranoid fear?

That, at least, is the thinking behind the “hygiene hypothesis,” a school of thought first proposed by David P. Strachan in 1989, and now experiencing a resurgence that’s probably a response to society’s mania for cleanliness. Strachan’s original study sought to explain why British kids with greater numbers of older siblings had fewer incidences of hay fever, speculating that perhaps it could be the fact kids with lots of older siblings tend to be exposed to greater numbers of germs. While it was greeted with skepticism early on, Strachan’s theory has since been confirmed. In fact, in the decades since, greater exposure to germs early in life has also been associated in epidemiological studies with lower levels of asthma, some allergies and even such autoimmune diseases as type-1 diabetes and multiple sclerosis. (Photo: Fotolia)