Germs in day-to-day life: no cause for panic

When are germs helpful, and when are they dangerous? And how often do I have to wash my hands to stay safe? An interview with Markus Egert, Professor of Microbiology and Hygiene at Hochschule Furtwangen University in Germany.

Interview: Anna Miller; photo: iStock

Mr Egert, are germs a bad thing?

Markus Egert: No, often the opposite is true. We need bacteria, fungi and viruses to stay healthy – in us, on us and around us. Over 99 percent of germs are harmless to humans, and most of them are actually very useful. At home at least. Despite this, many people walk around with a bottle of disinfectant thinking to themselves: the fewer germs I have in my house, the better.

Obviously it is a different story in the operating theatre. Some microorganisms are indeed dangerous for us. The most prominent of those at the moment is COVID-19. The great skill therefore is to come into contact with a wide variety of microbes while simultaneously protecting ourselves against infectious diseases. We have to find a balance between protecting ourselves and our children and biodiversity.

That is easier said than done.

True. But fortunately we have achieved a lot in this regard in the past. We are vaccinated against the most dangerous pathogens, such as hepatitis or the coronavirus. It is very important to vaccinate ourselves and our children. As a second step, hygiene is crucial, especially handwashing. All of these things are old news, but they have proven their worth. The third point is food hygiene. If you know how to cool food correctly, cook meat thoroughly and wash salad before consumption, you are already doing most things right.

How often should we wash our hands and clean surfaces?

It is fine to relax and allow germs to exist. The most important thing is to use our common sense. Most of us can sense intuitively when something is a good idea. If I spend the whole morning in bed, for instance, there is no point in washing my hands – after all, I haven't been in contact with anyone or anything. After a ten-hour train journey with three changes of train, on the other hand, my hands certainly do need a good clean.

If I am eating vegetables fresh from the farm, it doesn't matter if a bit of dirt remains on them – but I will wash them nevertheless. And if a slice of apple falls on the floor, my child can still eat it – after I have given it a wash to get the visible dirt off.

So too much caution is counterproductive?

Absolutely. It is important not to panic. Studies show that the more often small children between the ages of zero and three come into contact with a wide range of microbes, the more healthy they will be later – for the whole of their lives. Luckily the big pathogens have been suppressed in the industrialised countries, but allergies and asthma are on the rise. The assumption is that this is partly linked to a lack of contact with microbes. Or, to put it more simply: people are too cautious and as a result their immune systems do not get the necessary training.

For the same reason, it is also important that our drinking water is not sterile, for example. It does not contain any pathogens, just normal bacteria. Any attempt to make drinking water sterile would be nonsensical as microbes are good for us. And although it is fine to clean the kitchen after use, disinfecting it is pointless. 

In other words, respect is good, but fear is bad. 

Exactly, we have to be able to weigh up the risks.

Can I actively strengthen my immune system with the help of microorganisms ?

You can leave your town or city and go into the countryside as often as possible.  Stroke dogs, cats, sheep and horses – that has a positive effect on your immune system. There may also be a wide variety of germs on the commuter train I catch every morning, but I need a mixture of microorganisms from a natural environment. Forests, fields and the soil contain different organisms than cities. Studies show that people who live in rural areas have far lower rates of asthma and similar conditions.

Then everything is fine. 

Not entirely. The bad news is: by the age of 50, there isn't much we can do. Having been around for decades, our immune systems don't care at all if we go camping for three weeks. The groundwork for a good immune system is laid in childhood, possibly even in the womb. That is why it is so important that small children come into contact with as many microorganisms as possible. They should spend time in nature, eat a healthy diet and play in the dirt. And it's better to eat a slice of apple than to drink apple juice from a carton.