Yersinia pestis bacteria can cause three different forms of plague: bubonic, septicemic, or pneumonic.
In bubonic plague, the most common form, bacteria infect the lymph system and causes it to become inflamed. (The lymph or lymphatic system is a major component of your body's immune system. The organs within the lymphatic system are the tonsils, adenoids, spleen, and thymus.)
Usually, you get bubonic plague from the bite of an infected flea or rodent. In rare cases, Y. pestis bacteria can enter the body (through an opening in the skin) from a piece of contaminated material used by a person with plague.
Bubonic plague affects the lymph nodes (another part of the lymph system). Within three to seven days of exposure to plague bacteria, you will develop flu-like symptoms such as fever, headache, chills, weakness, and swollen, tender lymph glands (called buboes—hence the name bubonic).
Bubonic plague is rarely spread from person to person.
This form of plague occurs when the bacteria multiply in the blood.
You usually get septicemic plague the same way as bubonic plague—through a flea or rodent bite. You can also get septicemic plague if you have had untreated bubonic or pneumonic plague.
Symptoms include fever, chills, weakness, abdominal pain, shock, and bleeding underneath the skin or in other organs. Buboes, however, do not develop.
Septicemic plague is rarely spread from person to person.
This is the most serious form of plague and occurs when Y. pestis bacteria infect the lungs and cause pneumonia.
Symptoms usually develop within one to three days after being exposed to airborne droplets containing plague bacteria. Pneumonia begins quickly, with shortness of breath, chest pain, cough, and sometimes bloody or watery sputum. Other symptoms include fever, headache, and weakness.
Pneumonic plague is contagious. If someone has pneumonic plague and coughs, droplets containing Y. pestis bacteria are released into the air. An uninfected person can then develop pneumonic plague by breathing in those droplets.
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Last Updated February 03, 2015
Last Reviewed February 03, 2015