The Dirt on Germs
Terri Trespicio explains how to best handle everyday germs.
Irene Chansawang washes her hands 20 times a day. She doesn't get manicures or pedicures because she thinks nail salons are too dirty. She wouldn't dream of getting into the shower at the gym without wearing flip-flops, and keeps antibacterial wipes in her desk drawer.
"I wish it was a cultural norm in this country to wear those SARS masks when you're sick," says the self-professed germophobe.
In fact, all of us are like petri dishes: If you looked at your skin under a microscope, you would see it teeming with bacteria. But some scientists are suggesting that instead of running for the hand sanitizer, we should be grateful for the bugs -- some of them may be keeping us healthy.
The common wisdom is that the only good bug is a dead bug -- and in an age of flus like H1N1, it's no surprise. Every subway pole, doorknob, or coughing coworker could be a source of life-threatening illness. Physicians say a little common sense is still the best strategy to ward off colds and flu.
A Common-Sense Approach
"Try to wash your hands with soap and water a couple of times a day -- after handling food, after blowing your nose, or before eating," says Dalilah Restrepo, M.D., an infectious-disease specialist at St. Luke's-Roosevelt Hospital Center in New York City. But, she adds, "remember that bacteria challenges our immune system -- it teaches it how to deal with germs."
Continuous exposure to germs every day of your healthy life keeps you strong, agrees immunologist Mary Ruebush, Ph.D., author of "Why Dirt Is Good: 5 Ways to Make Germs Your Friends." "It keeps your immune cells, which are there to protect you, multiplying and reproducing."
Think of your immune system as an elegant army of highly trained killers. How will it stay in peak fighting form if it never sees the enemy? "The amazing thing about the human body is that it has an innate capacity to heal," says Evangeline Lausier, M.D., director of clinical services at Duke Integrative Medicine in Durham, North Carolina. "We have memory cells, which are a line of cells that can remember and reconstitute themselves."
And if the memory cells never meet a bug, they're shunted into making immune responses to non-foreign tissues -- autoimmune responses like allergies, asthma, and so forth. "It's a case of the idle mind being the devil's playground," she says.
There are about 50 trillion cells in your body, and the vast majority of them are bacteria that live in the digestive tract. "We're walking bags of bacteria," Lausier says.
And that's a good thing. Harmless flora in our gut produce K and B vitamins. Their sheer numbers block harmful bacteria from lodging in our intestines. Staphylococcus aureus, the bacterium known for antibiotic resistance (MRSA), innocuously coats our skin, and a variety of Lactobaccillus call the female reproductive organs home.
The beauty of antibiotics is their ability to kill bacteria that manage to gain a foothold among this crowd of do-good bugs. But antibiotics indiscriminately take out all bacteria -- bad and beneficial.
"The only bugs that survive are the ones that are resistant to the antibiotics," Lausier says. "And they can pass that resistance to other bacteria -- even different strains -- that weren't previously resistant."
Suddenly, you have a whole population of different bacteria resistant to current antibiotics, Ruebush explains, which can lead to real trouble if you need to wipe out a serious infection.
Of course, an antibiotic can be a wonderful thing. It's safe to say no one would choose to return to a time when a run-in with the wrong microbe meant dying from typhoid fever.
But it's not a good idea to run to the doctor for antibiotics every time you get a cold, and the use of antibacterial products is getting out of hand. Bacteria that encounter small doses of antibacterial chemicals over time can become resistant not only to the cleaning agent -- but to antibiotic drugs, too.
"Triclosan, one of the leading chemicals found in these household cleansers, targets a similar part of the cell as the antibiotics used to treat tuberculosis," explains Stuart Levy, M.D., a professor of medicine and molecular biology and microbiology at Tufts University School of Medicine in Boston. Studies are still inconclusive on whether bacteria resistant to triclosan -- found in a variety of products, from hand soap to toothpaste, laundry detergent, and acne medicine -- are also resistant to antibiotics.
The potential was enough, however, to inspire the Canadian Medical Association last year to call for a ban in Canada on all household products containing triclosan.
When Ruebush talks about dirt, she means more than just compost and soil. "It's an absence of extraordinary cleanliness," she explains. Getting dirty means being exposed to the bacteria, viruses, fungi, and parasites we commonly call germs.
For microbiologists like John Stanford, Ph.D., now retired from the University College of London Medical School, dirt actually means dirt. For more than three decades, Stanford studied Mycobacterium vaccae, aka the "dirt vaccine," a bug ubiquitously found in soil.
On a trip to Uganda in the 1970s, Stanford realized places that had rich stores of M. vaccae in the soil and water had the fewest children with tuberculosis and leprosy. His theory? M. vaccae and the dangerous microorganisms that cause TB and leprosy contain similar proteins; exposure to the good bug teaches the body how to fight off the dangerous one.
You don't need to dig in African soil to get a dose of M. vaccae. Christopher Lowry, Ph.D., a neuroendocrinologist at the University of Colorado at Boulder who is studying the health benefits of the bacterium, says you're probably encountering it every day. It's in the dust you breathe, municipal water supplies, and soil.
"M. vaccae is part of a class of bacteria we call Old Friends," Lowry explains. His research in 2007 found that injecting 1/10 of a milligram of M. vaccae into the lungs of mice (to mimic what happens when we inhale bacteria) stimulated the release of serotonin in the brain, in amounts comparable to those spurred by antidepressants, which means dirt can even boost your mood.
But studies are still looking at the effectiveness of the bug. Lowry's next project? Seeing whether giving mice M. Vaccae orally has the same effect.
"We've coevolved with these organisms throughout human evolution," he says. "They're in the environment all around us. And because they don't cause disease, our immune system has learned to tolerate them. If our immune system tried to attack them, and get rid of them, it would cause real damage."
All of this is an argument for letting your kids get in the dirt -- childhood is when the immune system is still learning the ropes germwise.
"Studies have looked at kids living on farms versus kids living in urban areas, and there's a big difference in the rate of asthma and dermatitis," says Levy, author of "The Antibiotic Paradox." "The theory is that on a farm you're getting contact with lots of different microbes, and that builds a strong immune system."
A Better Battle Plan
Instead of worrying about bacteria, Lausier says, "we ought to be thinking about how to strengthen our own defenses, which might be lying there dormant."
Stay fortified by reducing stress, exercising, and cutting back on meat raised on antibiotics. Eat more antiinflammatory foods like fish, which contain immune-boosting omega-3 fatty acids.
A strong immune system is what you really need to defend yourself against a virus like H1N1, Lausier says, "but if you get a cold or flu, control the symptoms rather than sterilize the field."
Ruebush couldn't agree more. "Your environment is a place that has lots of other creatures living in it," she says. "You really don't want to be killing things. You just want to keep them down to a dull roar."