Plague (cont.)

Septicemic plague

This form of plague occurs when the bacteria multiply in the blood.

How do you get it?

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 had untreated bubonic or pneumonic plague.

What are the symptoms?

Symptoms include fever, chills, weakness, abdominal pain, shock, and bleeding underneath the skin or other organs. Buboes, however, do not develop.

Is it contagious?

Septicemic plague is rarely spread from person to person.

Pneumonic plague

This is the most serious form of plague and occurs when Y. pestis bacteria infect the lungs and cause pneumonia.

How do you get it?

You get primary pneumonic plague when you inhale plague bacteria from an infected person or animal. You usually have to be in direct or close contact with the ill person or animal. You get secondary pneumonic plague if you have untreated bubonic or septicemic plague that spreads to your lungs.

What are the symptoms?

Symptoms usually develop within 1 to 3 days after you are exposed to airborne droplets of 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.

Is it contagious?

Pneumonic plague is contagious. If someone has pneumonic plague and coughs, droplets containing Y. pestis bacteria from their lungs are released into the air. An uninfected person can then develop pneumonic plague by breathing in those droplets.


Y. pestis is found in animals throughout the world, most commonly in rats but occasionally in other wild animals, such as prairie dogs. Most cases of human plague are caused by bites of infected animals or the infected fleas that feed on them. In almost all cases, only the pneumonic form of plague (see Forms of Plague) can be passed from person to person.


A health care provider can diagnose plague by doing laboratory tests on blood or sputum, or on fluid from a lymph node.


When plague is suspected and diagnosed early, a health care provider can prescribe specific antibiotics (generally streptomycin or gentamycin). Certain other antibiotics are also effective.

Left untreated, bubonic plague bacteria can quickly multiply in the bloodstream, causing septicemic plague, or even progress to the lungs, causing pneumonic plague.

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