What are we doing to ourselves?

An interesting idea emerged from conversation over dinner with a colleague recently: While it is clear that hand hygiene is foundational for both hospital and community infection prevention, there may be an immunological price to the now all-pervasive focus on hand hygiene in the general population.

Let me explain. Hygiene is one of the pillars of public health and infection prevention, though we still struggle to practice what we know globally. Semmelweis showed us the need for clean hands in the clinical environment, and the notion of ridding hands of germs has evolved since then. Today, alcohol based hand rubs (ABHRs) are prominent in daily life. People rub their hands with "hand sanitizer" before eating out, after riding the bus, after using the restroom, and even at their desks throughout the day. What could possibly go wrong with such an awareness of hand hygiene?

Potentially, nothing. The importance of hand hygiene is undisputed and indisputable in infection prevention. That said, I often see people using ABHR very frequently throughout the day and it makes me wonder if such use of ABHR is eroding not only the transient flora of our hands, but also the resident flora. What is on our hands ultimately ends up challenging the immune system, via oral ingestion, absorption through rubbing the eyes, or inoculation via scrapes and cuts on the hands and fingers. Constantly challenging the immune system with a diversity of biologic agents gives rise to broad immunity.

Might we be eroding the frequency and diversity of that challenge, and thus the strength and diversity of the immunological protection, with such pervasive use of ABHR? This general notion, that cleanliness might have deleterious, unintended community-level consequences, is not new. It's been discussed within the context of polio, for example, and there is speculation about inverse relationships between cleanliness and asthma.

I'll close by noting that ABHR is but one of the several tools society currently employs to kill the spectrum of microbes in our immediate environment. There are also antimicrobial wipes and antimicrobial soaps. The weapons of mass microbial destruction are many and proliferating. They obviously have their place in the clinic but, regarding their sometimes near-obsessive use in the community, are they helping or hurting us in the long run?

(image source: David Hartley)