TORONTO - Cursing your sick colleague for the infection you can feel settling into your chest? You might want to aim the finger of blame closer to home.

It's entirely possible you may have infected yourself with whatever respiratory bug has latched onto your lungs. The same can be said about the some of the stomach-wrenching gastrointestinal ailments people occasionally get.

That's because with a number of infections, people sometimes self-inoculate. They take germs they picked up on their hands when they were hanging onto bus poles or shaking a hand someone recently sneezed into and they deliver the bugs to places where those bugs can go from harmless to disease causing.

In a nutshell, they stick germ-coated fingers into their mouths, they rub their eyes, they are even known to poke a finger into a nostril.

And voila! Bug on skin becomes bug on mucus membrane — a much more porous surface and an easier route to a warm and welcoming place for the bug to migrate towards.

Handwashing and alcohol gels can slough those germs off your fingers. And that's why public health officials repeat the handwashing mantra relentlessly, particularly during cold and flu season.

But a group of researchers suggests there's a part of the prevention equation that public health folks don't stress often enough: If you kept your fingers out of your mouth-nose-eyes, you'd lower your risk of self-inoculating.

"People touch their faces, touch their mouths, pick their noses and all of that. And in those behaviours they can bring these viruses that are on their hands to the muscosa ... where they can really infect us," says Wladimir Alonso, an infectious diseases researcher at the U.S. National Institutes of Health's Fogarty International Center.

Alonso and some colleagues wrote a letter to the journal Clinical Infectious Diseases recently to make the point.

They had done a small study where they observed 249 randomly selected individuals in public spaces in Florianopolis, Brazil and on the Washington, D.C., subway system. The individuals they observed touched common surfaces and their mouth and nose area at a rate of 3.3 and 3.6 touches respectively an hour.

Their point? Handwashing alone can't keep up with the infection potential of self-inoculation events. Or as they put it, "...the opportunities for hand re-contamination in public settings occurs at a much higher rate than any viable hand washing frequency."

They suggest public health campaigns should also teach people about how they infect themselves by touching their mucus membranes, so they become more aware of the role these behaviours could play in acquiring infection.

Dr. Jody Lanard likes the suggestion. A risk communications expert based in Princeton, N.J., Lanard monitors public health messaging about influenza closely, and says officials often overstate the benefits of handwashing.

That's not to say Lanard doesn't believe in handwashing. She is in fact a big fan of the practice. But she'd prefer it if authorities stuck to the science — and says there isn't that much evidence handwashing cuts down on flu transmission. (That doesn't mean it doesn't, just that there aren't a lot of studies showing that it does. Studies aimed at answering this kind of question can be devilishly hard to do.)

Lanard thinks public health messaging should suggest that it's plausible that frequent handwashing reduces the risk of acquiring colds and the flu. "I love that word plausible. It covers up a whole lot of lack of good evidence."

And she says the idea of telling people about self-inoculation makes sense, because there are times when people simply cannot wash their hands, such as during a commute on public transit.

The author of a book on hygiene says public health messages about handwashing and self-inoculation should be synergistic. "I don't think it's an either-or thing," says Dr. Bonnie Henry, author of "Soap and Water and Common Sense."

Henry is the medical director of communicable disease prevention and control services at the British Columbia Centre for Disease Control. She says it can be difficult to get people to think about self-inoculation.

"It doesn't resonate so much when you say 'Don't do something' that people aren't really conscious of doing in many cases," she says.

"Making them aware of it is important. But I think it's inevitable that you're going to touch your face and you really need to make sure that you clean your hands regularly because that's what's going to protect you at the end of the day."

"I always say 'It's not having bugs on your hands that's the issue. It's when you go to eat your sandwich or rub your eye. That's when you're going to get sick from it.' So I think the two messages have to go together."

Alonso says it's important to keep the issue in context. He doesn't want to turn people into hypochondriacs.

While people can self-inoculate, it isn't going to happen every time a person puts a finger into their mouth or rubs the bottom of their nose. That said, when there is a disease outbreak, such as a flu pandemic, having people aware of the role they can play in triggering their own infections could be helpful in slowing spread, he says.

"I do think it's important to make people aware that we touch our face way more than we realize, and that that's how we can sometimes transmit things," Henry agrees.

Note to readers: This is a corrected story. An earlier version misidentified the journal in which Alonso's letter was published

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  • Question 1

    You have a runny nose and a minor scratchy throat. Can you still work out?

  • Answer: Go For It

    Follow the general rule of thumb that if all your symptoms are above your neck (sniffles, sore throat, minor cough) you're okay to exercise. "Exercise neither helps nor hurts the symptoms of a moderate cold," says Nieman. "Don't do anything too severe, and it should be okay." But know your limits. Over-exertion can make symptoms last longer, he warns.

  • Question 2

    You have chest and lung congestion and you feel achy allover. Can you still work out?

  • Answer: Sit This One Out

    The other side of the above-the-neck rule is -- you guessed it -- the below-the-neck rule. "If it's a fever, in your chest, you have tiredness, don't exercise at all," says Nieman. "Wait until the symptoms go away and then slowly get back to your normal routine." Not sure if you have a fever? Err on the side of caution and skip today's workout.

  • Question 3

    By "neck rule" standards, you're in the clear, but you had planned a high-intensity workout for today. Can you stick to the plan?

  • Answer: Better To Tone It Down

    It's best to tune down the intensity, even if your symptoms are not severe. Start out at about <a href="http://www.health.com/health/condition-article/0,,20257420,00.html" target="_hplink">50 percent of your normal intensity</a>, and if you feel okay after 10 minutes, gradually bump it up to about 80 to 90 percent max, Health.com reports. "Don't push the pace," warns Nieman, "but a brisk walk should be fine." Strength-training, stretching and yoga can also be good low-intensity options for <a href="http://www.fitsugar.com/Exercises-Do-When-Youre-Sick-20156271" target="_hplink">sick-day workouts</a>, according to FitSugar.

  • Question 4

    You have a low fever, but you'll just sweat it out, right?

  • Answer: Wrong

    "If the average person goes out to 'sweat it out' they could really hurt themselves," says Nieman. Anecdotally, heavy exertion when you have a fever seems to cause viruses to spread in a way that may lead to long-lasting symptoms similar to chronic fatigue syndrome, like tiredness, lower athletic performance and joint pain, says Nieman. "Just take it easy," he says. "There are too many risks involved."

  • Question 5

    True or false: A light workout will make your symptoms better.

  • Answer: False

    While exercise can create some immediate <a href="http://www.mayoclinic.com/health/exercise/AN01097" target="_hplink">congestion relief</a>, according to the Mayo Clinic, (we've all seen runners shooting snot rockets!) Nieman says there's no research to back up those boogers. And if you have a fever and flu-like symptoms, you'll also put yourself at additional risk. Your heart pumps blood from your muscles to your skin to help cool you off when you exercise. If you have a fever, your temperature will be even higher than normal during your workout, putting your heart under <a href="http://www.runnersworld.com/article/0,7120,s6-241-286--9082-0,00.html" target="_hplink">greater pressure to keep you cool</a>, <em>Runner's World</em> reports. "If the individual has any indication of a fever or general aches and pains, or muscle weakness, or they are just disinclined to exercise but then go out and force themselves to do it, they're really asking for it," says Nieman. Studies of animals exposed to the flu virus have found that heavy exercise resulted in longer and more severe symptoms, and even a higher rate of death, he explains.

  • Question 6

    Should you stay out of the gym when you're sick?

  • Answer: Not Necessarily

    Just keep in mind some common-sense <a href="http://www.webmd.com/cold-and-flu/features/exercising-when-sick?page=2" target="_hplink">etiquette tips</a> from WebMD. Cover machine surfaces with a towel and be extra diligent with the sanitizer spray after you're finished. Wash your hands before and after your workout (and <a href="http://www.cdc.gov/flu/protect/habits.htm" target="_hplink">more often in general</a>). However, if you're going to be sneezing or blowing your nose constantly, do us all a favor and stay home.

  • Question 7

    True or false: If you exercise harder, you will have even more protection against colds.

  • Answer: False

    "The happy medium is 30 to 60, maybe 75 minutes; in that arena there's great protection," says Nieman. "But as soon as you get to 90 minutes or more of very heavy exertion, then the immune system starts to go the other way." In his 1990 study of over <a href="http://www.ncbi.nlm.nih.gov/pubmed/2266764" target="_hplink">2,300 runners of the Los Angeles Marathon</a>, Nieman and colleagues found that the day after the marathon, runners were six times more likely to get sick. "The immune system can't perform its job as well," he explains.

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