An infection is the growth of unwanted bacteria, viruses, or other one-celled organisms in the body.
Infections interfere with the normal body functions.
Once an infection becomes established, you should contact a physician about possible medical treatment. Viruses and bacteria are everywhere, but they do not always cause infections. Whether or not this happens depends on how the organism enters the body, what kind and how many viruses and bacteria are contacted, and the health of the person involved. Since viruses and bacteria that cause infections cannot be seen, you may ignore them or fear the illnesses they can cause. A more effective approach is to try to increase the ability of your body to resist infection, avoid the activities that make infection more likely, and reduce the contact with bacteria and viruses, whenever possible, by using common sense precautions.