Germs Are All Around Us: How Can We Stay Healthy?

From the Lecture Series: An Introduction to Infectious Diseases

By Barry C. Fox, M.D., University of Wisconsin

We are all exposed to a huge variety of germs every day. In fact, if Google Glass eventually offers microscopic vision, we may walk around with gloves on and never eat in a restaurant again. Microbes are all around us, and the question is, “What do we have to worry about?”

Hygiene concept. Man is showing dirty hands with many viruses and germs
(Image: vchal/Shutterstock)

Recently, my wife and I were in the Delta terminal at LaGuardia Airport. We were surprised to see sleek new updates, not only in the terminal itself but also a tablet computer at every seat at the gate. You can even tap on the screen to order lunch and a beverage is delivered to your seat within 15 minutes. If I only had an ultraviolet, or UV, light wand with me to sanitize the tablet in front of me.

Contaminated technology is something we need to think about, but how much of a germaphobe do you want to become? There are steps you can take to protect yourself from germs without becoming obsessed about them.

This is a transcript from the video series An Introduction to Infectious Diseases. Watch it now, on The Great Courses Plus.

The important point to remember while examining all the case situations presented is that just because there are germs on a door handle or a saltshaker does not mean that you will automatically become ill by using or touching these objects. The goal is to make you cognizant of the special circumstances where pathogenic viruses or bacteria may be avoided, with a little knowledge and some common sense.

Learn more about the dynamic world of infectious disease

Our Several-Billion House Guests

One of the first culprits to look at for germs is our homes. At least several billion microorganisms are keeping you company in your home. Most of them are harmless, but some could be potentially dangerous. Some locations are the worst offenders.

Did you know you can sterilize a wet sponge by putting it in the microwave for two minutes? (Image: FOTOGRIN/Shutterstock)

The kitchen is one of the dirtiest places in the home. One surprise is that the kitchen floor, just in front of the sink, has more bacteria than the trash can. And the sponges around the sink own a large burden of bacteria as well.

You can easily sterilize a wet sponge by putting it in the microwave for two minutes. Just be careful taking it out of the microwave— it’s going to be hot.

Now note if you wash chicken in the kitchen sink, and either a sponge falls in, or you turn on the faucet with unwashed hands, both can become contaminated with virulent intestinal pathogens like campylobacter or salmonella. Some people don’t realize that when you flush a toilet, bacteria in the toilet disperse into the air. Anything within a three-foot radius could be contaminated. If you can, close the lid before flushing.

… In fact, the average toothbrush after brushing has over 10 million germs. However, as long as it’s your own toothbrush, these are your own bacteria, and are not harmful.

Even toothbrushes lying around can be contaminated. The average toothbrush after brushing has over 10 million germs. However, as long as it’s your own toothbrush, these are your own bacteria, and not harmful. Resist the urge to share toothbrushes; besides bacteria, they could pass on blood-borne viral diseases such as hepatitis B and C and, of course, infectious mononucleosis without a kiss.

Other things to watch out for are sharing makeup, which may result in sharing bacteria, and sharing razors, which may inadvertently share MRSA or blood-borne viruses. While in college, my daughter called me for an immediate consultation when she found out her roommate had used her razor.

It seems that some cultures have got it right about shoes: leave them at the door. You not only can keep the house cleaner, but you don’t track in allergens and potentially pathogenic germs. One study found as many as nine different pathogenic bacteria were in the dirt or other assorted things stuck to the bottom of your shoes. You can then transmit them to tile or carpeting all over your home.

Germs Camping Out on Your Touchscreen

Our personal electronic devices are also a source of pathogenic germs. If you are the only one using your tablet, laptop, or cellphone, similar to your toothbrush, you’re likely OK, since the germs are your own. However, be careful where you place these devices. Studies have shown that 16 percent of cellphones have intestinal bacteria on them.

Studies have shown that 16 percent of cellphones have intestinal bacteria on them.

Given this fact, how long can germs live on surfaces? In general, cold and flu germs from sneezes can live on hard surfaces for up to 48 hours. The swine flu has been shown to survive in the environment for up to five days. Think about this before you hand your cellphone over to your sick spouse, family member, or friend. If you’re worried about this, you could purchase a device that you can put over your cellphone, which bombards the phone with ultraviolet light to kill 99 percent of bacteria, for about $25.

Learn more: Which Germs in Your Daily Life Matter?

Germs on technology devices and elsewhere have opened up a new market of products to kill germs and protect you in the process. It’s difficult to clean your laptop or tablet with bleach or alcohol, but new products are emerging like washable screen protectors and disposable covers that enclose the entire device. These may be particularly useful in healthcare environments, where there is a huge potential for pathogens to easily travel from workers’ hands to tablets or computers.

Image of customer using a communal tablet device
Studies have shown that most germs on community touch-screen devices were nonpathogenic staphylococci from the skin. (Image: Monkey Business Images/Shutterstock)

As for the tablets in the terminal airport, if you use them, be sure you wash your hands thoroughly afterward. Washing your hands is the one thing you can do to significantly reduce the chances of getting sick.

What might be slightly more problematic at the airport terminal is that, unless you carried a miniature hand sanitizer bottle with less than four ounces of fluid, the sanitizer is probably in your medicine bag, being loaded on the plane.

Speaking of touchscreens, one research project found thousands of bacteria on the Amtrak touchscreen at the train station. Since most germs were nonpathogenic staphylococci from the skin, you can take some partial reassurance. But you should figure out your own strategy for touchscreens, including grocery stores, ATMs, ticket kiosks, and airport check-ins.

Germs Enjoy Traveling, Too

Speaking of traveling, what do we need to know about germs in advance of going on a trip? A study was done in 2011 on sites of possible contamination during a cross-country trip, for example, in a personal car, on commuter train seats, and in a taxi. The findings were not that surprising after examples from the home and electronic devices. There were hundreds of bacteria on the rental car seats, as well as staphylococcus on the train and taxi seats. Most of these, again, are non-pathogenic bacteria.

Learn more about global travel, war, and natural disasters

It’s important to know that if there are some potential pathogens like E. coli, our immune systems should be strong enough to prevent major illnesses. Realize, too, that every pole you hold on the train, bus, or subway has the possibility of spreading colds and flu virus, and the bacteria we’ve all been discussing. Viruses are more likely to cause illness than bacteria since the mucous membranes of the nose and the eyes are more easily breached by viruses. Germs are everywhere.

Viruses are more likely to cause illness than bacteria, since the mucous membranes of the nose and the eyes are more easily breached by viruses.

What does the research say about planes? You may have heard speculation that contaminated air circulating on airplanes is responsible for spreading germs. However, a revealing study now cites low cabin humidity potentially as the biggest culprit if you become ill. Why is this?

At low levels of humidity—around 10 percent when flying at 30 to 35 thousand feet—the mucous membranes in our noses and our throats become drier. In a normal environment, viruses and bacteria are trapped and moved on by the cilia, or hair sweepers, to be destroyed by infection-fighting white blood cells.

When the membranes are dry, the mucus may get too thick to move easily. Therefore, viruses and bacteria stay in the upper respiratory tract for longer periods. This low humidity factor also applies to wintertime conditions for the transmission of germs.

According to multiple sources, one of the germiest places on the plane is likely the restroom, but there are a lot of areas that are a close second, like airplane trays or aisle seat handles. Of course, with lots of people in small spaces, there are more opportunities to share germs directly from person to person. But what do you do in a confined space if the person next to you on the plane is coughing or sneezing?

The most dangerous neighbors are those sitting within a two-seat radius. Why? Importantly, 6 to 8 feet constitutes a safe distance that bacteria and viruses cannot easily be transmitted by aerosolized means of coughing or sneezing because most of the bacteria or viruses will fall to the ground in that distance. This makes it difficult to keep your distance from seated neighbors on the plane.

There are a few germs with exceptions to the 6 to 8 feet distance, and these include a few viruses and Mycobacterium tuberculosis, or TB. TB is exactly three microns in size, the exact size of dust particles in the air, so TB can float from minutes to hours over hundreds of feet. It’s no wonder that tuberculosis has been with us for centuries and is still one of the most contagious diseases in the world.

… it’s no wonder that tuberculosis has been with us for centuries, and is still one of the most contagious diseases in the world.

One highly publicized case of transmission of pathogens during air travel occurred in 1998 when a passenger with active TB infected 13 other passengers who sat in his vicinity on the plane. It may come as a surprise that the actual airplane air is as well protected as the inside of a hospital. Airplanes have high-efficiency air particulate filters, or HEPA filters, with the ability to filter more than 90 percent of known particulate matter, including those that may be suspended in the air. Don’t think you should worry too much about it. Just take appropriate precautions, if you can, for sneezing neighbors.

Interior of large commercial airplane with unrecognizable passengers on their seats during fligh
One highly publicized case of transmission of pathogens during air travel occurred in 1998 when a passenger with active TB infected 13 other passengers who sat in his vicinity on the plane. (Image: Matej Kastelic/Shutterstock)

Pass The Germs, Please

“Pass the salt and pepper.”

“Can I have the ketchup, please?”

Oh, no, what about restaurants? In a recent study, menus carried the most germs—185,000, to be exact. This was followed, in second place, by the peppershaker, having 11,000 germs. This information will probably have you picking up the salt shaker with a napkin, or running frenetically to the restroom to wash your hands after ordering your food. But, similar to the transportation example, most of these bacteria will be harmless.

You can’t control the unusual germ and you can only do what you can, but the point is to protect yourself as far as your common sense can take you, then relax and eat.

Germs on Vacation

What about hotels? Concerns that the bedspread on hotel beds is an item that doesn’t get cleaned enough might be well-founded. Some scientists have recommended removing this item, and the concept of bedbugs is beyond the scope of this article.

Are there other hotel items that aren’t living up to standards? One study found that light switches and bathroom floors were all contaminated with intestinal bacteria. Light switches had 216 bacteria per square inch. But the dirtiest site of all was the television remote. It’s interesting to note that one hotel chain has now implemented a new cleaning program in its hotels—scanning with black lights and UV light wands to spot and destroy germs.

Learn more about infectious diseases

Germs in the Gym

Closeup of a sport bike in the gym.
Many people don’t think much about germs in the gym, but in fact, gyms are a haven for germs. (Image: Kzenon/Shutterstock)

After returning from your trip, you’ve decided to hit the gym due to overindulging on vacation. Many people don’t think much about germs in the gym, but gyms are a haven for germs. Think about the circuit-training scenario—you move from machine to machine, touching handles, changing weights, lying on mats, and often sitting on other people’s sweat. You contract real illness from this.

Most gyms now supply cleaning solutions and towels to wipe down the equipment. Use it. Keep any cuts or injuries fully covered when working out at the gym. The most serious germ you can acquire in the gym is methicillin-resistant Staphylococcus aureus, or MRSA. While you likely have the common sense not to share locker room towels, this was not an uncommon practice for teenagers in gym class, until the risk of MRSA was more widely publicized. At least four professional football teams have been plagued with MRSA in their locker rooms over the past decade.

The most serious germ you can acquire in the gym is methicillin-resistant Staphylococcus aureus, or MRSA…at least four professional football teams have been plagued with MRSA in their locker rooms over the past decade.

Also, both plantar warts—a virus, and athlete’s foot—a fungus, can be contracted by going barefoot on gym floors and locker rooms. Wear shower shoes in the shower and locker room. This is where the term “athlete’s foot” comes from. For those who do yoga, bring your own personal mat, and wear socks until you get to it. It’s especially important for “hot” yoga classes where people sweat a lot.

Putting Up A Smart Defense

Now knowing about where germs lurk, how do we keep ourselves well?

A good place to start is by looking at respiratory hygiene. Many diseases are spread by coughing and sneezing. When you cough or sneeze, germs can travel up to 6 or 8 feet. Using a tissue, your hand, or a bent arm to cover your mouth and nose when coughing or sneezing can help stop the spread. Throw used tissues away and clean your hands afterward.

One important basic fact: we touch our faces with our hands around 20 times per hour. Try not to touch your eyes, nose, and mouth, which are mucous membranes, and provide easy access to your body for germs. Even when your hands appear to be clean, germs are often spread this way.

Can ultraviolet technology help us? UV lights or wands utilize short- wavelength UV radiation that is harmful to microorganisms. You can purchase one for about $40 that claims to kill 99 percent of bacteria. If you use the wand effectively, the surfaces need to be smooth so germs can’t hide in the cracks. UV is effective in destroying the germs by disrupting their DNA, leaving them unable to perform vital cellular functions. UV disinfection has a real role in hospital environments for TB and Clostridium difficile spore disinfection.

It’s also been used increasingly to sterilize water. The Environmental Protection Agency (EPA) has accepted UV disinfection as a method for drinking water processing plants to contain the spread of parasites like cryptosporidium, giardia, or even for virus inactivation.

Learn more about the intricate components of your body that try to protect you from dangerous infectious diseases

Alcohol Sanitizers vs. Germs

Using wash hand sanitizer gel pump dispenser.
Since they are convenient and they act quickly, alcohol-based hand sanitizers are widely used in hospitals and marketed in many stores. (Image: Zyn Chakrapong/Shutterstock)

How effective are alcohol-based hand sanitizers? They contain 60 to 70 percent alcohol, killing most germs instantly by denaturing, or twisting out of shape, the proteins in bacteria and most viruses. Since they are convenient and they act quickly—within 15 seconds—they are widely used in hospitals and marketed in many stores.

Alcohol, however, is not selective. It kills both pathogenic bacteria as well as commensal, friendly bacterial flora. It’s good to know, though, that research has shown that alcohol hand sanitizers do not necessarily pose any risk by eliminating good microorganisms that are naturally present on the skin. This is because your body quickly replenishes the good microbes on your hands. However, alcohol also strips the skin of outer layers of oil, which may have negative effects on the barrier function of the skin.

Alcohol hand gels can also be effective against germs. The Centers for Disease Control’s (CDC) Clean Hands Campaign has instructions on how to use hand sanitizers properly. Put the alcohol gel in the palm of one hand and apply enough of the product to wet your hands completely. Next, you rub your hands together, and you clean all parts of the hands— fingers, thumbs, nails, and wrists. Rub your hands together until they’re dry. You know you’ve used enough of the hand rub if it takes 25 to 30 seconds to dry on your hands.

The Mayo Clinic also has a list of recommended conditions for sanitizing hands with gels or washing hands with soap and water. A small sampling of this list includes: before preparing or eating food, before treating wounds or giving medicine, before touching sick or injured people, before inserting or removing contact lenses, after preparing food, especially raw meat or poultry, after using the toilet or changing a diaper, and after touching an animal, animal toys, leashes or animal waste.

Closeup image of hands being washed
Norovirus is usually spread by food workers who don’t wash their hands properly. (Image: hxdbzxy/Shutterstock)

Alcohol is not a replacement for washing hands with soap and water. To see how alcohol gels may not live up to all their expectations, let’s take a further look at a small round virus known as Norovirus. It’s the most common cause of gastrointestinal illness in the United States, affecting millions yearly. It’s also the most common cause of food-borne illnesses, usually spread by food workers who don’t wash their hands properly.

And it’s contracted by ingesting food or drinks contaminated with the virus, touching surfaces that are contaminated, then putting fingers in the mouth. This cycle is important because it describes the fecal-oral route of transmission.

Also, sharing items like serving or eating utensils with someone who is sick with the virus, or on a buffet, for example, can lead to Norovirus infection. This is another reason that there are hand-washing signs posted in restrooms that serve the public—to remind people that germs can be transmitted unintentionally by unwashed hands.

Alcohol gels do work against many viruses, but not well against the Norovirus. The CDC has now placed guidelines for hand-washing for cruise ships on their website, which includes hand-washing with soap and water, not just alcohol gels as the first line of defense.

…alcohol gels do work against many viruses. But unfortunately, not very well against the Norovirus.

If you are using soap and water, you should wash your hands for about 24 seconds, lathering fully and covering all sides of your hands and fingers to completely remove bacteria. Twenty-four seconds is two rounds of the Happy Birthday song. If you wash your hands correctly with plain soap and water, you have a good chance of avoiding many opportunities to get sick.

Those 24 seconds can seem like an eternity when you’re in a hurry, but it will be worth the wait. Unfortunately, estimates of how many people actually wash their hands after using the bathroom run no greater than 50 percent, so beware.

Among types of soap, you may wonder if anti-bacterial soaps add anything to the routine hygienic process. There are several kinds of anti-bacterial soaps, the most common kind sold in stores contains a product called triclosan, while the most commonly used in hospitals contain ingredients povidone-iodine or chlorhexidine gluconate.

Learn more: Antibiotics: A Modern Miracle Lost?

Triclosan has been used for years in the healthcare setting as a disinfectant. However, some animal research has shown that it might disrupt our endocrine or hormone system. Triclosan is used in many antibacterial soaps and even some kinds of toothpaste. Because of these concerns, studies are underway to determine whether this ingredient should be removed from products. In 2014, Minnesota became the first state legalizing a measure banning triclosan-containing products.

Clean Home, Healthy Life

Besides soaps and gels, other disinfectants are available. Old-fashioned bleach is still known to be 99 percent effective against pathogens, thanks to its active ingredient, hypochlorous acid. It attacks proteins in bacteria, causing them to clump together and die. This reaction is similar to the way bacteria respond to high temperatures—like the sponge in the microwave. A dilute, 1 percent bleach bath has been used to help families that cross transmit skin pathogens like MRSA.

A list of disinfectants is registered with the EPA that can be found on its website. You might be interested and surprised that the list includes Thymol, a derivative of the herb thyme. This can now be found even in bathroom cleaners made by companies that are responding to consumer requests for less toxic cleaning products.

Another earth-friendly product, vinegar, is useful for killing some things, but not others. For example, it is effective for killing the flu virus but not staph. It seems to be about 90 percent effective against other bacteria, and about 80 percent against other viruses. It’s cheap, non-toxic, biodegradable, it has anti-microbial properties due to its 5 percent acetic acid.

Tea tree oil may be added to commercial products, such as body wash, skin cream, and nasal ointment, due to its antimicrobial properties. Its structure appears to disrupt the cell membrane of MRSA. The clinical efficacy in body wash and creams to reduce the number of MRSA germs has been documented.

5 Second Rule: Fact or Myth?

Lastly, you probably have heard about the “5-second rule” where if you drop a piece of food, is it still okay to eat if you pick it up within five seconds? Under most circumstances, the answer is, it’s probably okay. A 2014 study from England showed that time is a significant factor in the transfer of bacteria from a floor surface to a piece of food. The type of flooring the food has been dropped on also affects it, with bacteria least likely to transfer from carpeted surfaces and most likely to transfer from laminate or tiled surfaces.

Most germs that are crawling in the environment are usually commensal organisms and benign to most of us, but individuals with compromised immune systems, such as those receiving chemotherapy or taking moderate doses of steroid medications, should resist the urge to eat food that has been dropped on the ground or the floor.

However, scientists at Clemson University tested the five-second rule by applying the pathogenic Salmonella germ to tile, wood, and carpeting, and they examined how the germs survived to see if they would transfer to slices of bread and bologna on these surfaces. They learned that within five seconds, both foods picked up hundreds to thousands of bacteria. Therefore, not every surface germ may be harmless.

Take this information and decide how it applies to your daily life. Just having an awareness of the germs in our environment is the first step towards staying as healthy as possible.

Common Questions About Protecting Yourself From Germs

Q: How do you protect yourself from germs at the gym?

To protect yourself from germs at the gym, you should go when there are fewer people, wash your hands frequently, and sanitize equipment.

Q: What are the common preventative measures against communicable diseases?

Common preventative measures against communicable diseases include washing your hands often, avoiding densely-packed public places such as subway stations during rush hour (especially during flu season), and using condoms to avoid catching sexually-transmitted diseases.

Q: What suggestions can you give to prevent outbreaks of infectious diseases?

To prevent outbreaks of infectious diseases, you should avoid sharing personal belongings such as hairbrushes or deodorant, don’t overuse antibiotics, prepare your food safely by cooking meat at the correct temperatures, and washing produce before use.

Q: What are the five key ways in which infection can spread?

The five key ways in which infection can spread are through airborne germs, person-to-person, infected objects, animals, and food/water.

This article was updated on April 15, 2020

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