Which is not be a mechanism through which an infectious disease can emerge?

a. decreased transmissibility

b. different portal of entry

c. increased incidence

d. increased virulence?

The correct option is A.

An infection disease is a type of disease which a person can acquire as a result of contact with the person who has the disease or as a result of contact with body fluids from that person. Infectious disease can be spread through increased virulence, increased incidence and different portals of entry. A decreased transmissibility reduces the probability of an infectious organism been transmitted.