|e coli scupture, Luke Jerram|
Think twice the next time you reach for the antibacterial wipes. You might not be doing yourself any favors. In our attempts to achieve an increasing sterile world, we may be wiping out the beneficial bugs along with the bad guys.This month's Utne Reader (new tag line: Cure Ignorance) ran biologist Rob Dunn's Conservation article about "why cleanliness might be making us sick". It's one of dozens of recent pieces discussing the hygiene hypothesis, linking decreases in diversity in the human microbiome to ever increasing rates of autoimmune illnesses, from mildly annoying to life threatening. Think allergies, eczema, Crohn's disease, juvenile arthritis, Grave's-- maybe even MS.
In autoimmune diseases, the body launches an attack on itself. There's increasing support that these over-reactions are linked to some bad early training. To attack an invader, you have to first identify it. To identify, you have to be exposed to it, usually several times. Theorists wonder if the lack of early exposure prevents the immature immune system from properly keying out the villains.
Evidence is growing. Science published a study in March that found that mice exposed to microbes early in their development kept their invariant natural killer T cells in check. Germ-free mice had high levels of inkT cells in their lungs and were much more prone to inflammatory diseases. These specially bred and raised mice aren't new to the experimental scene. A study published in 2011 linked their lack of normal gut bacteria to changes in brain development and behavior.
It's too early to know how directly this translates to humans. But there's something going on. We know this: babies raised with pets tend to have fewer colds and ear infections. Pets aren't quite as OCD as people. They have no problem walking around for hours in the dirt, or eating what's on the floor, in the yard or crawling with vermin. And they're unlikely to wash their paws or maws before they greet you. This early exposure to the dirty world seems beneficial to babies.
|SARS viral lace, by artist Laura Splann|
Our bodies have ten times the number of microbial (virus, bacteria, etc) cells as human cells. Their genes outnumber us 360 to 1. The microbiome in our gut is especially vital. By now, even the least geeky of us is familiar with the term "probiotics"-- beneficial bacteria that colonize our gut and aid in everything from vitamin absorption and food digestion to fighting inflammation. It's not unusual for MDs to recommend probiotics (whether in pill form or just a good cup of Nancy's yogurt) to patients on antibiotics. That's because antibiotics are efficient little killers, but not very discriminating-- they mow down most everything in their path. Wired magazine had a great infographic showing that for one particular species of beneficial bacteria, populations remained low even two years after a single 7 day treatment with clindamycin (for 9 months, the only remaining Bacteroides species was one particular clindamycin resistant strain).
Antibacterial soaps, lotions, tissues, wipes. Antimicrobial gloves and sneakers, even underwear. Sneezing into elbows, fistbumping instead of handshaking. You'd think we'd all be healthier. But the CDC reports that C-difficile infections are at an all time high. C-diff is found normally, and benignly, in most of us, kept in check by the beneficial bacteria in our gut. When that's out of whack, C-diff can go wild, with potentially lethal results. Those recently or currently on antibiotics are at the greatest risk.
It's not just the little guys that are beneficial. There's renewed interest and many recent investigations into the role of parasites in helping human immune systems. Men's Health ran a lengthy article about treating ulcerative colitis and Crohns with (ok, ick) intestinal worms.
For more on the microbiome, click the links above or check out these articles: