When we hear the word “bacteria” we usually think of dirt and diseases, but the truth is that many of them fulfill essential functions for our body. The population of microorganisms that lives with us exceeds the number of our own cells in a ratio of 10 to 1: for every human cell we carry 10 microbes with us. And we need them to live.
For example, the bacteria present in our guts – the famous intestinal flora – help us to produce vitamins, such as folic acid, and to absorb important minerals from food. The problem is that sometimes there are necessary and useful bacteria in one part of the body that end up in another area where they are not only not helpful but can cause problems. And this includes bacteria normally found in feces, which can end up in our mouths if we're not careful enough.
In his new book, The Life of Poo, Professor Adam Hart, a biologist and science writer at the University of Gloucestershire, explains how we can avoid that bacteria from one part of our body (or, rather, from other parts, from other bodies) end up where they should not.
In a preview of his book published by The Daily Mail, Hart explains that the most common route unwanted bacteria enters our bodies is through the mouth. "In other words, we eat them," says the scientist. “And this includes bacteria that we normally find in feces, as well as others that you might find wherever you touch something.”
Most people worry about cleaning their house thoroughly, taking a shower every day –something that is not always good– or changing their clothes daily, but not so many give importance to the hygiene of our body parts guilty of most pathogen transmission: hands.
Recent studies, cited in Hart's book, show that people lie a lot about how often they wash their hands. Although between 94 and 96% of the population claims to do it every time they go to the bathroom, the truth is that only 61% of women and 37% of men actually do it.
You're doing it wrong
It doesn't seem like you have to do a master's degree to learn how to wash your hands, but the truth is that many people just soak for a bit thinking that it's more than enough. Actually, as Hart explains, water has to be there, but it doesn't matter if it's hot or cold, and it doesn't even have to be clean.
In a study conducted in a Pakistani slum, where people washed with faecally contaminated water, it was found to be no worse for this purpose than sterile water. Always, yes, that soap was used.
Only half of the men wash their hands with soap and water, 35% wash only with water and the remaining 15% do nothing
“It's the use of soap and hand rub that really matters,” Hart explains in his book. “When soap molecules come into contact with water, tiny soapy spheres called micelles are formed. These trap grease and oil (and whatever else has stuck to them) and allow it to mix with the water, which is then washed down the sink.”
Soap doesn't actually kill bacteria, it just washes them off our skin, but water by itself doesn't do the trick to rid our hands of bacteria. Something that doesn't seem to matter to many men. Only half of the men wash their hands with soap and water, 35% wash only with water and the remaining 15% do nothing. Women are much more careful: 78% use soap and water.
Apart from the need to use soap, it is also important that we take the time to wash our hands thoroughly. A study published in the Journal of Environmental Health in 2013 showed that only 30% of people wash for more than 9 seconds. 70% use less than 8 seconds (including 10% of people who don't even wash).
Although it seems that four or five seconds are enough to wash our hands, the truth is that the more time we use, the cleaner they become. And studies agree that the ideal is to rub our hands between 15 and 30 seconds.
Drying well is also important. Bacteria move like fish to water on wet surfaces and are more easily transferred between wet hands. And, although there are discussions about it, it seems clear that hand dryers are not as effective as towels.
Other ways to get infected
Although dirty hands (yours or someone else's you come into contact with) are the most common pathogen transmission element, it's not the only one. Leaving the toilet seat open is a common (and highly tolerated) oversight in homes and public toilets. And the matter is worrying considering that, when we flush the toilet, the fecal germs are distributed throughout the room as if we were spraying a feces aerosol through the bathroom, up to a radius of two meters. And, yes, they also reach our toothbrush.
Most E. coli are not harmful, and in fact, you've been brushing your teeth with contaminated toothbrushes for your entire existence
Before the disgust caused by what you just read makes you pull out your teeth, think that your toothbrush has always been there and you don't have diarrhea every day either. As Hart explains, while it may be teeming with bacteria like E. coli, and most likely is, you're not necessarily going to get sick after brushing your teeth: “Most E. coli isn't harmful and In fact, you have been brushing your teeth with contaminated toothbrushes for your entire existence.”
Nor is it easy to get infected because a contaminated person has touched a doorknob. As Hart recounts, many things have to happen for that to happen: "Not only does the infected person have to wash their hands poorly, but the bacteria must also survive long enough on a dry metal surface and, in practice, many spices." They don't survive on that kind of surface. You also have to touch the right part of the knob – ideally with wet hands – catch the bacteria and quickly transfer it to your mouth.”
In the end, the easiest way to catch a bacterial disease is to go have a bowel movement right before eating and not wash your hands. That, or go to eat just before you shake hands with someone so slutty they offer you a wave right after they go to the loo and don't wash up.