Key Points at a Glance
- Ever since the pandemic began, we've been very cautious whenever we feel tired or under the weather.
- Could it be another SARS-CoV-2 infection? That's what many people are wondering.
- But whether it's spring, summer, fall, or winter: viruses are always circulating—and not just coronaviruses.
- It's not just viruses that can make us sick—bacteria can, too.
Anthropologists and evolutionary theorists have recently revised the estimated age of Homo sapiens based on the latest discoveries. According to their findings, our earliest ancestors lived in what is now the Maghreb as far back as about 300,000 years ago. That is remarkable—and yet a mere fraction of how long bacteria and viruses have been native to our planet. Research estimates 3.6 billion years, meaning these tiny pathogens have inhabited Earth for about twelve times as long as we have.
Are bacteria and viruses living organisms?
It is difficult to say whether people in North Africa at that time also suffered from colds or the flu. However, it’s not entirely unlikely, considering that there are probably around 300 cold viruses. It’s also possible that some of these viruses are significantly older and were already causing runny noses, coughs, and general malaise in early human species.
3.6 billion years is a period of time that accounts for 80 percent of the time since the Earth’s formation 4.5 billion years ago—so why don’t viruses continue to evolve? They do so by mutating; this can be clearly observed in coronaviruses. Apart from that, viruses have found a niche; they do not need to evolve into more complex forms in order to survive. However, that does not mean they are living organisms; unlike bacteria, viruses have no metabolism and no cell wall.
How Viruses and Bacteria Make Us Sick
Viruses are therefore not considered to be living organisms in their own right, whereas bacteria are—albeit as the simplest form of life. There is also a huge difference in their size: while a virus is only about 20 to 300 nanometers long (that is, 0.00002 to 0.0003 millimeters or 0.02 to 0.3 micrometers) and is only visible under an electron microscope, a bacterium grows to a full micrometer—that is, one-thousandth of a millimeter.
While bacteria, once they have entered our bodies, multiply through cell division and spread throughout our organism, viruses reprogram or destroy our body’s own cells. In most cases, however, the reprogrammed cells are tasked with replicating the virus, which leads to illness. In the case of a bacterial infection, on the other hand, it is usually the metabolism of the invaders that makes us sick.
How do viruses or bacteria infect us in the first place?
The transmission routes of pathogens have been a much-discussed topic long before the coronavirus. Germs are essentially everywhere—on doorknobs, on smartphones, on public transportation—and eventually find their way onto our hands and into our bodies. That’s why it often helps to disinfect your hands regularly. But they also enter our bodies through the air—via droplets containing pathogens that a sick person expels when coughing, sneezing, or speaking, and which travel through the air to reach our mucous membranes.
Bacteria and viruses can also enter the human body through the blood or other bodily fluids. If food or water is contaminated and we consume it, we can also become infected. And last but not least, mosquitoes are often carriers of pathogens; there are several examples of this, such as malaria.
Prevention is only possible against viruses
The big question has long been how best to prevent these pathogens. The distinction between viruses and bacteria is relatively clear. Viral diseases can be prevented through vaccinations, such as the winter flu or COVID-19. That said, it’s important to note that a vaccination doesn’t necessarily prevent the disease itself, but it does at least ensure a milder course of the illness and, as in the case of COVID-19, a significant reduction in mortality.
People who are unvaccinated and contract a viral infection may, under certain circumstances, find relief with antiviral medications. These are drugs that can inhibit viral replication. In the case of a bacterial infection, however, antibiotics are an effective treatment. These are medications that specifically target and kill the invading bacteria. Preventive measures such as vaccinations, however, are not effective against bacterial diseases.
