Consider the chain of infection. in the chain, an example of a "method of transmission" is:

The chain of infection is a term referring to a sequence of events leading to the infection of a host organism by a pathogen microorganism. The chain is composed of six links: the pathogen, reservoir, portal of exit, means of transmission, portal of entry and the new host. The methods of transmission can be either direct or indirect. An example of direct transmission is the inhalation of a flu virus by the future host after another host sneezed and threw the virus in the open air. An example of an indirect transmission is the entering of the pathogen in the human body through an insect, such as a mosquito.