Medical Science - Other

Difference between Viruses and Bacteria

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Viruses and bacteria have a major common feature. They are both capable of inflicting serious damage and even death on the human. plant or animal kingdom. For this reason, many people tend to use the terms interchangeably. However, there are distinct differences between the two, both in their make up and in the way they can affect your health. These are some of the differences between a virus and a bacterium (bacteria is the plural form, and the term most commonly used).

Good guys versus bad guys

Bacteria can be either bad or good. The good bacteria help to make vitamins to keep the body healthy, as well as forming a barrier against infection in the nose and mouth, among other areas. Good bacteria in the digestive tract help the body to process food and eliminate waste and toxins. Many of the most common foods would not be available without bacteria - dairy products such as yogurt and cheese are good examples.

Viruses, on the other hand, are very often the bad guys, although there are some exceptions to this rule, as there are to all rules. Viruses can be responsible for causing cancer, AIDS, various strains of influenza and smallpox, and other nasty diseases. While bad bacteria can also cause nasty infections in the respiratory organs, urinary tract and sinuses, these can be treated with antibiotics and are not necessarily life threatening.*

Viral infections are much more harmful, and more difficult to treat, as the virus is encased in a protective shell called a capsid. This is virus armour, and it's one of the reasons why viruses can wreak so much havoc on health.


Both viruses and bacteria are simple structures. A virus consists of a strand of genetic material surrounded by a capsid - a protective layer made up of proteins which protects the genetic material and helps to transmit the virus to other host cells. Some complex viruses have a third layer or 'envelope,' which serves to offer more protection to the virus by making it appear to be a living cell and fooling the immune system.

A bacterium has an outer cell wall which shapes and supports the entity. The cell is filled with cytoplasm, which contains ribosomes, a neucleoid and plasmids. Ribosomes allow the bacterium to synthesise proteins for growth and cell division, and the other components provide the genetic blueprint of the cell.

A virus cannot live an independent life. It relies on a living host and its sole function is to reproduce itself. A bacterium is capable of independent life and reproduction and also serves many functions within the body.


Both viruses and bacteria are able to reproduce, but they do this in different ways. A virus is acellular, and needs a living cell as a host in order to reproduce itself and create havoc. It's formed of genetic material, either deoxyriboneucleic acid (DNA) or ribonucleic acid (RNA). Living cells have both these components, viruses have one or the other. When the virus finds a host cell, it uses the cell's resources to copy itself, then ruptures the cell wall so the virus clones can spread to other cells and repeat the process.

A bacterium consists of a single cell which can multiply on its own. The process is a simple method of asexual reproduction called 'binary fission.' The bacterium reproduces very quickly, and each cell contains the same DNA structure, so the new cells are clones of the original single cell.

A virus is in effect a parasite which needs a living host to multiply. If it has no host it lies dormant in its protective shell.  A bacterium is essentially self-sufficient in any circumstances, and can reproduce rapidly under the right conditions.

Treatment options

Most bacteria will respond to treatment with antibiotics. The immune system produces antibodies to fight off the infection and prevent further infection from the same bacterium, but this takes about a week, so antibiotics are also prescribed to assist the process.

While there are antiviral medications available, as yet there is no effective treatment against most viruses*, and it's a case of sit back and wait until the virus runs its course. Again, the body produces antibodies, which take around a week to deal with the virus. At the same time, the infected cells produce proteins known as 'interferons,' which prevent the spread of infection to other cells while the immune system deals with the viral threat.*

While harmful bacteria - called pathogens - can produce dangerous and even deadly  threats to health, a virus is a much more sinister proposition, chiefly because there is little that can be done to kill it if the immune system is unable to deal with the invading virus.





More about this author: Sandra Piddock

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