Transmission is the stage in which the infectious agent gains a host and infects it. There are three main modes of transmission:
A. The transmission by contact:
Human-to-human transmission
Auto-infection (Some infections are endogenous, that is, they are caused by microorganisms that are part of normal flora but can become opportunistic pathogens.)
Indirect Contact Transmission (Indirect Contact Transmission refers to the propagation of a pathogen from a reservoir to a host through an object)
Droplet transmission (when a person coughs)
B. Transmission by a vehicle
Waterborne transmission
Foodborne transmission
Air transmission
C. Transmission by an animal vector
Mechanical transmission (In this type of transmission, insect vectors propagate infections passively.)
Biological transmission (This mode of transmission of vector-borne infections is much more complex, since the vector plays an active role in it.Normally, passage through the vector represents an essential step in the development of the pathogenic microorganism.)
