A pathogen is the name given to a group of organisms which cause diseases within the human body and are able to do so because of their ability to invade the bodies environment. Pathogens cause damage to the tissues within the human body by replicating themselves at a fast rate in order to invade as many near by cells and give themselves a better chance of survival before the immune system starts to fight them off (Fullick, 1998, pp. 8–9). They are passed on from one person to another and that's what makes them infectious. Most infections are spread through direct or indirect contact with a contaminated person who is a host of the disease or infection. The most common type of transmission is through airborne bacteria and viruses being passed
