A<unk>  is an Infectious<unk>  that is readily spread (that is, communicated) by transmission of a pathogen through contact (direct or indirect) with an infected person. A<unk>  is often known to be<unk>  before medical science discovers its causative agent. Koch's postulates, which were published at the end of the 19th century, were the standard for the next 100 years or more, especially with<unk> s caused by bacteria. Microbial pathogenesis attempts to account for<unk> s caused by a virus. The<unk>  itself can also be called a contagion.
Contagious disease
Notifiable disease
Human pathogen
Natural reservoir
Progressive disease
Chronic condition
Vulnerable adult
Heterogeneous condition