Don't touch that doorknob. Don't sit on that toilet. And cover that grimy old book! When I was growing up, my mother's warnings seemed endless. Mom, who studied English literature, was certainly no microbiologist. No matter. Lacking science, she was still convinced that, beyond the safe zone of our stainless steel kitchen sink and sanitized bathrooms, the inanimate world loomed with germs and imminent harm. Was she right or wrong?
There's no simple answer to that question. Hospitals, breeding grounds for infection, have performed cultures of everything from whirlpools to surgical scrubs. But in the real world of airport armrests, public telephones and worn-out dollar bills, there are precious few culture data. The message to laypeople goes something like this: Hey, pal, out there, you're on your own.
Having said this, we do know a fair bit about common germs, their habitats and their survival. Take Staphylococcus aureus, the classic villain behind boils and eyelid sties as well as some serious problems like osteomyelitis (bone infection), endocarditis (heart valve infection) and toxic shock syndrome. On any given day, 20% to 40% of us harbor this guy in our nose.
The common cold is an even more familiar plague. We all know to recoil from a wet sneeze. But guess what? The risk doesn't end there. Rhinoviruses live for hours on skin and environmental surfaces. Long after your sniffling friend has left, with a simple move of the finger to nose or finger to eye, you can transfer the viral invader to his next assembly plant, namely you.
What about toilet seats? In grammar school, they seemed downright perilous, swarming with unmentionables. Now that I'm a grown-up and a doctor, I realize one of those unmentionables was Neisseria gonorrhoeae.
Gonorrhea is a gummy infection of private parts transmitted almost exclusively by sex. Years ago, adults would sometimes claim they caught gonorrhea in a public restroom. That's doubtful, according to a 1979 research study. Although N. gonorrhoeae survived two hours in fresh air, in random samplings of 72 public lavatories, not a single seat tested positive.
Toilet seats remind us of an important principle, however. When dealing with any surface--wet versus dry--you should choose the latter. To most bacteria and viruses, drought still equals death.
Let's leave STDs for diarrhea. With the rising use of children's day care, we gained a natural laboratory. Today, more than 50% of U.S. tots attend day care, suffering three times as much diarrhea as their home-based peers. Use your imagination, and the reason should come clear. There's a thin film of feces that periodically coats the domain of diapered toddlers and the newly toilet-trained. At the same time the feces are flowing, every two to three minutes the little ones are also inserting fingers, toys and other articles into their mouths.
Proof positive of fecal pollution in day care comes from a three-month study conducted in the early 1980s of adults, children and objects in six centers in Houston. Seventeen percent of classroom objects and 26% of toy balls tested positive for fecal bacteria, doubling to 34% and 52%, respectively, during an active outbreak of diarrhea. During the outbreak, one third of the children also had fecal bugs on their hands.
Bacteria are not the only diarrhea culprits in day care--intestinal viruses and parasites also abound. Rotavirus, the world's leading childhood diarrhea virus, typically causes a weeklong illness. During that time, its victims excrete a billion or more infectious particles per gram of stool. Hell-bent on survival, the viruses remain viable at least four hours on human hands, several days on nonporous surfaces and weeks in water. They even defy common hand-wash agents and antiseptics. Score one for the microbes.
Not all modern day care equals hygiene hell. Since national health and safety standards for out-of-home child care were first published in 1992, quality programs have stressed cleanliness, disinfection, exclusion of ill children, immunization and outbreak reporting. When considering day care, savvy moms and dads can also play detective. Start by noting the availability of lavatory sinks and the frequency of hand-washing by staff, then move on to food routines. If toddlers' snacks are prepared by hands that also diaper, you might want to enroll your child somewhere else.
A cutting board in a Minneapolis eatery is the centerpiece of our last fable. In the 1970s, more than 100 patrons of this popular department store restaurant came down with Hepatitis A, another germ usually passed by food and water laced with feces. However, in this outbreak, eating a sandwich prepared on the board was the only common factor linking victims. In retrospect, the surface was contaminated by saliva from a careless food handler in the early stages of infection.
Truth be told, only 50% of cases of Hepatitis A reported yearly to the Centers for Disease Control and Prevention are traced to a specific food or water source. Could the remainder be spread by objects and human hands? University researchers in Ottawa think so. In 1991, they planted Hepatitis A on the finger pads of volunteers and, four hours later, found more than enough virus left to propagate disease.
So maybe Mom was right: hidden hazards do lurk in the inanimate world, and they're poised to climb aboard our human craft. But wait. If that's so, shouldn't we be ill all the time? There's the rub. Generally speaking, if you're healthy, you withstand more than you succumb. In other words, infections are the exception not the rule. But just to hedge the bet, I'll leave you with a veteran's rule of thumb. You really can't wash your hands too much.
Just what mom always said.