Infectious diseases spread when a healthy person encounters a pathogen expelled by someone sick, such as through a cough, sneeze, sexual activity, or contact with fecal material. The amount of that pathogen necessary to make that healthy person sick is the infectious dose.
Isolation
This policy involves separating people known or suspected to be infected with a contagious disease from those who are not sick to prevent them from transmitting disease to others. The definition of “suspected” is based on whether the person is showing symptoms of a contagious disease or whether they met certain laboratory criteria demonstrating they have likely been infected.