What is the difference between bacterial and virus infections?

As a statement of the obvious, one infection is caused by a bacterium, the other by a virus. But the primary difference lies in the essential nature of these two causes of infection. A bacterium is a living, single-celled organism. It may live on its own or group with other cells to form more complex structures. At the highest levels of collective living, they come to represent small animals with protecting sheaths (providing the same functions as a skin) and multifunctional cells serving the needs of the whole. Although the different types of bacteria are, for the most part, not harmful to humans. Some may even perform beneficial functions within the body. Unfortunately, some may produce toxins that poison the cells around them.

The majority are usually found living outside the body, whether on inanimate surfaces or in animals and insects. The average human will only meet a small number of the types of bacteria with many living in the seas and deep underground. Thus, the bacteria in our immediate environment are transmitted to humans by being inhaled, through a cut or wound, by being eaten, or through the bite, sting, etc. of an animal or insect. Others live on or inside the body. Whether they are immediately toxic or only later become so, depends on the type of the bacterium and the circumstances in which they enter. Once active and producing toxins, they may also become infectious or contagious so that one human carrier may communicate the disease to others, say through a cough or sneeze.

Unlike a bacterium, a virus is not alive in the accepted sense of the word. It is no more than a package of genetic material. Unlike bacteria which reproduce, a virus requires a host in which to multiply. For these purposes, the host can be a human, animal or plant. Without a host, the virus ceases to exist. However, once inside the body, a virus behaves in the same way as a bacterium, i.e. it invades human cells. When the virus enters, it hijacks the cells’ reproductive facility and uses each host’s cell to replicate itself. The effect is usually to destroy the cell. Some viral infections like influenza and HIV are contagious.

However, the key difference between the two forms is the method of treatment. Bacteria are potentially susceptible to specific or broad-spectrum antibacterial antibiotics. None of these antibiotics have any effect on a virus. Similarly, the treatment for a viral infection is an antiviral drug and this form of drug has absolutely no effect on any bacteria. To ensure that you get the right treatment, you should always contact your doctor and get a proper diagnosis before taking any antibiotic.