What is Plague?

Plague is an infectious disease caused by the bacterium Yersinia pestis, which is found in rodents and their fleas throughout the world. There are three types of plague: bubonic, pneumonic and septicemic.

Bubonic plague is the most common. Infection appears in the lymph nodes, causing them to swell and become painful. Infection results from the bite of an infected flea that has fed on an infected rodent, such as a rat.

Pneumonic plague is the most deadly form of plague but the least common. It occurs when Y. pestis infects the lungs. It can be spread through airborne droplets released through coughs or sneezes by a person or animal, especially a domestic cat, with pneumonic plague.

Septicemic plague can occur with either bubonic or pneumonic plague. It occurs quick and has a rapid progression.  It is fatal if not treated.


What are the symptoms of Plague?

All forms of plague begin with flu-like symptoms. The first signs of illness are fever, chills, headache, weakness and muscle pain, and can include nausea, vomiting, diarrhea and abdominal pain. Pneumonic plague results in pneumonia that causes a cough producing bloody or watery sputum. The pneumonia progresses over 2 to 4 days and may cause septic shock and, without early treatment, death. Septicemia plague takes only 1 to 6 days for symptoms to show.  Bleeding underneath the skin or other organs is common and toes/fingers may become gangrenous.


This fact sheet provides basic information only. It must not take the place of medical advice, diagnosis or treatment. Always talk to a health care professional about any health concerns.


Source:  Ontario Ministry of Health and Long-Term Care, Public Health Division.


For Further Information

Call the Infectious Disease Program: (807) 625-5900

or toll-free 1-888-294-6630

Health Topic
Diseases & Infections