Both viruses and bacterium are tiny pathogens that are invisible to the naked eye but that are among the most common causes of infectious disease. In fact, because of their microscopic nature, both viruses and bacteria easily and stealthily transfer from one person to another, especially during contagious outbreaks. Despite these similarities, and despite their nasty reputations for causing disease, bacteria and viruses are quite different.
Bacteria and viruses differ in a few distinct ways. The biggest difference is whether they are alive or not. They also differ in terms of size, mode of infection and interactions with one another. Below you can explore the main differences between these disease-causing agents.
The biggest distinction between viruses and bacteria is their abilities to sustain themselves. Bacteria are living organisms that have the capacity to make their own energy, generate their own food, reproduce and move around. For this reason, bacteria can live and thrive in many environments, including soil, water, plants and, of course, the human body.
When most people think of bacteria, they do so in terms of disease. The truth is, though, that less than 1% of bacteria make us sick. The remaining 99% serve several vital (and some not-so-great) functions for our ecosystem. For instance, bacteria’s most vital role is to decompose organic matter and recycle the chemicals that contribute to the creation of new plant and animal life.
Whereas bacteria are living, productive organisms, viruses are not. Viruses are dormant compounds that can only grow and reproduce when within a “host.” To become “alive,” a virus must hijack the biochemicals of a living cell. This hijacking leads to destruction and/or mutations that, if allowed to continue, can cause illness and disease. Unlike bacteria, viruses have few beneficial functions.
To the human eye, both bacteria and viruses are so tiny as to become invisible. However, in the small matter world, the two agents are non-comparable in terms of size.
In comparison to viruses, bacteria are giants. Measuring about 0.4 micron (or one millionth of a meter), bacteria are considered “microscopic,” meaning humans can see them with a microscope. Viruses, on the other hand, range from as small as 0.02 to 0.25 micron, making them submicroscopic. Submicroscopic organisms cannot be seen with an ordinary light microscope and require a more intense tool called an electron microscope. Viruses’ small size may explain their inability to sustain themselves without external help.
Because of their distinct biochemistries, the ways in which bacteria and viruses cause illness and disease are varied. When a virus invades a host cell, it multiplies by the thousands, destroys or damages the initial cell in the process, and then moves on to new cells. For this reason, a virus’s attack is systematic, spreading from one point in the body outward. Examples of systematic viral infections include polio, influenza, AIDS, measles and COVID-19.
When bacteria invade, however, they are more varied in their approach to destruction. Bacteria will generally only attack when an opportunity arises and, when it does, it will not spread to other parts of the body. For this reason, most bacterial infections are localized. It is also worth noting that bacterial infections are not always caused by the bacteria themselves but rather, the toxins, or endotoxins, they produce. Examples of bacterial infections include food poisoning, tuberculosis, pneumonia and tetanus.
Bacteria are living organisms, whereas viruses are not. As a living organism, bacteria are not immune to a virus’s attack. If a virus so chooses, it may make a bacterium its host, taking over and attacking it. Bacteria are unable to do this to viruses.
Despite several differences between the two types of agents, both viruses and bacteria can be transmitted in similar ways. Below are the top ways in which you may spread or contract a viral or bacterial infection:
These are just a few of the more common ways in which both viruses and bacteria spread from person to person.
The types of symptoms a person develops when sick with a viral varus bacterial infection depends largely on the area of the body that becomes infected. For instance, if you develop a bacterial infection on the skin, you may experience swelling, redness, pain and discharge from the site. If you have a viral infection, on the other hand, you may develop nausea, pain, joint pain, vomiting and/or jaundice (yellowing of the skin and eyes).
For both bacterial and viral illnesses, however, the immune system may activate to rid the body of the infectious agent. In this case, you may develop symptoms that resemble those of many common illnesses, such as the following:
A key difference between viral and bacterial illnesses is the way in which they are treated. Bacterial infections are treated with specific types of antibiotics. Which type of antibiotic will work for an infection depends on the bacteria in question. When the right antibiotic is used, it will prevent the bacteria from multiplying and eventually kill it.
To many peoples’ chagrin, antibiotics are ineffective against viruses. Treating viral infections typically involves self-care and symptom management. If you have a virus, your doctor may recommend that you do the following:
Because of the drastically different ways in which doctors treat viruses versus bacterial infections, it is important to first understand what type of infection you have in the first place.
Though both viruses and bacteria can make you ill, they are drastically different organisms with unique characteristics and means of treatment. Because we live in a world surrounded by both, it is important to understand each’s unique traits and means of treatment, as well as measures you can take to protect yourself against infection.