What is "pneumonic plague"

Bubonic plague \Bubonic plague\ (Med.) a severe and often fatal disease caused by infection with the bacterium Yersinia pestis (formerly Pasteurella pestis), transmitted to man by the bite of fleas, themselves usually infected by biting infected rodents. It is characterized by the formation of buboes, most notably on the groin and armpits, and accompanied by weakness and high fever. The disease was known as the black death, and was responsible for several devastating plagues throughout the middle ages. When lungs became infected, the disease was called the pneumonic plague. It is still found occasionally in poor areas of undeveloped countries but is rare in developed countries.

n. plague that can spread through the air from person to person; characterized by lung involvement

Pneumonic plague, a severe type of lung infection, is one of three main forms of plague, all of which are caused by the bacterium Yersinia pestis. It is more virulent and rarer than bubonic plague. The difference between the versions of plague is simply the location of the infection in the body; the bubonic plague is an infection of the lymphatic system, the pneumonic plague is an infection of the respiratory system, and the septicemic plague is an infection in the blood stream.

Typically, the pneumonic form is due to a spread from infection of an initial bubonic form. Primary pneumonic plague results from inhalation of fine infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a mortality rate from 90-100%.