Microbes get around by hitch-hiking. A disease is communicable when the microbe causing the disease can move from the infected host and establish infection in another host. If the microbe is easily transmitted, then the disease is called contagious. When a person’s normal flora causes disease or when a person comes contact with a microbe that lives in the soil and was not acquired in anyway from another human, then the disease is called non-communicable.

There are three primary methods of transmission of microbes and the diseases caused by the microbes. We may refer to a disease as being transmitted, but microbiology students understand it is the microbe that is actually transmitted. Transmission patterns of microbes are often extremely complex; however, the primary routes of transmission are direct or indirect. For our discussion we will include vectors as a separate mode or method of transmission.