A highly virulent form of plague with extensive involvement of the lungs: Pneumonic plague occurs as a sequela or result of bubonic plague or as a primary infection.

In pneumonic plague, there is severe coughing that produces a bloody, frothy sputum (a thick unpleasant substance that is produced in the throat and lungs when someone has an infection) and there is also labored or very difficult breathing that exists for the person.

Death is almost inevitable unless the pneumonic plague is diagnosed and treated early.