It is cold time. The neighbor on the bus sneezes, the child coughs. The colleague complains about her runny nose. Above all, many people want one thing: don't get infected. But how dangerous are pathogens in everyday life? Can the grab handle on the bus really make us sick? And should we disinfect the keyboard and desk when someone else has worked there?
As soon as the temperature drops and the immune system weakens, people are particularly easily infected with cold and flu viruses. In addition to the classic influenza viruses, doctors distinguish more than 200 types of cold viruses. Every second runny nose is caused by rhinoviruses.
When coughing and sneezing, the pathogens reach the air in the form of small droplets containing viruses – and may be inhaled by other people. In addition to this droplet infection, viruses can also be passed on by smear infection. Anyone who touches an infected object and then touches his face makes it easy for the pathogens to penetrate the body through the mucous membranes of the eyes, nose and mouth.
Whether on door handles, shopping carts, on handrails on escalators or in transport: germs lurk everywhere. In 2016, a group of American researchers examined which microorganisms travel on surfaces such as those in the Boston subway. The scientists found most of the microorganisms on handles, somewhat less on seats and on the screens of ticket machines (The American Society of Microbiology Journals: Hsu et al., 2016).
The majority of the germs discovered were harmless human skin dwellers, which had been found many times before in public, highly frequented places (Cell reports: Kang et al., 2018). The research team also found bacteria from the intestinal flora in the seats. Similar to skin germs, intestinal germs are not uncommon in public transport. Sounds disgusting, but do you really get sick if you use a contaminated handle on the subway?
Bacteria love crumbs on the keyboard
Ernst Tabori is medical director at the German Hygiene Advisory Center in Freiburg. He is familiar with microbial finds in public places. "Where there are many people, there are also many germs. It is not the total number of microorganisms as such that determines a possible infection, but primarily which germs are involved," says the hygienist. The decisive factor is whether there are pathogens that cause infections among the microbes.
Most germs and intestinal germs are largely harmless. Sometimes, however, diarrhea pathogens such as noroviruses or rotaviruses also spread through handles, displays or banisters (Federal Center for Health Education). And with noroviruses: even a tiny dose can make you sick (Hospital hygiene up2date: Small, 2018).
Your own workplace is also a playground for germs. This shows a study that researchers from the University of Arizona had carried out for the hygiene manufacturer Kimberly-Clark, who – you have to take into account – should have a business interest in finding contaminated places. According to the study, most germs can be found on phones. There are almost 4,000 on average per square centimeter. On the other hand, there are only 510 on keyboards, almost clean.
Most germs come from your own body anyway, at least if you don't share your desk with colleagues. Nevertheless, experts advise cleaning office objects at regular intervals. Especially of any leftovers from the breakfast roll. Because food residues can promote the growth of bacteria (American Journal of Infection Control: Messina et al., 2011).