What is the bubonic plague?
Bubonic plague (an infection of the lymph nodes) is recognized globally as the most common form of plague. Other forms include: septicemic (an infection of the blood), and pneumonic (an infection of the lungs).

Plague is a disease that has had a devastating impact on human beings across the world for centuries. There have been three major pandemics of plague in recorded history, although The Black Death ― the bubonic plague that killed millions of people in the 14th century ― remains perhaps the world’s most infamous plague pandemic. Today plague is still endemic in various parts of the world. It remains a disease that can arise unexpectedly in the 21st century. 

Microscope of the Yersinia pestis bacteria.

What causes the bubonic plague?
Plague is a highly infectious disease that affects animals and humans, and is caused by the bacterium Yersinia pestis.

How do you catch bubonic plague?
Most commonly, by being bitten by an infected rodent or prairie dog living in areas where bubonic plague is known to exist. (see map below for North American locations)

What are the symptoms?
Describing the bubonic plague’s symptoms in people, the Federation of American Scientists notes.

“The incubation period ranges from 2 to 10 days with an acute onset of malaise, fever, chill and weakness. Up to 24 hours later, one or more lymph nodes become swollen, forming a bubo 1-10cm wide. The buboes are extremely tender and painful, often developing in the groin and sometimes under the arms and on the neck. If the patient is not treated with the appropriate antibiotics, the bacteria can spread to other parts of the body: then bubonic plague may progress into septicemic form, spreading Y. pestis throughout the bloodstream to the rest of the body, including to the central nervous system where it can cause meningitis, and to the lungs, causing pneumonic plague.”

What is the treatment for the bubonic plague?
Bubonic plague is treated with antibiotics. Patient are treated in the hospital and placed in isolation. Often they will need oxygen and respiratory support.

If detected early (within the first 24 hours of symptoms), the mortality rate is 15%, but untreated, the mortality rate rises to 50-90%.

Any person known to have close contact with the patient needs to be identified, observed and given preventative antibiotics.

Can one person get the plague from another?
Yes, but only if it is the pneumonic plague which can be spread through bacteria-containing droplets in the air. Human to human transmission is very rare.

Buboes on the leg
Photo: CDC

Can bubonic plague be prevented?
Only through pest control. A vaccine does not yet exist.

Where can you catch the plague today?
Plague continues to surface on several continents today. According to the Centers for Disease Control and Prevention (CDC), between 1900-2010 in the U.S. alone there were “999 confirmed or probable human plague cases … [and] in recent decades an average of seven human plague cases have been reported each year.”

The plague is most common in rural and semi-rural areas of western United States and is acquired in the late spring – early fall. (see a map of reported plague cases in the US) The last case reported in Canada was in 1939.

Every year, between 1,000-2,000 worldwide cases of plague are reported to the World Health Organization (WHO), although actual numbers may be higher. Although plague epidemics have occurred in Asia, Africa, and South America, the CDC reports that since the 1990s “most human cases have occurred in Africa.” (see a map of reported plague cases in the world)

In 2012, on the island nation of Madagascar, 60 people died of plague: the highest number worldwide. In December 2013, The Guardian reported that bubonic plague took the lives of 20 villagers in Madagascar in “one of the worst outbreaks globally in recent years.” According to The Guardian, the International Committee of the Red Cross warned “that the island nation was at risk of a plague epidemic.”

World Health Organization 
Centers for Disease Control and Prevention 
Federation of American Scientists  
UPMC Center for Health Security   
The Guardian (Dec. 12, 2013)

For more information on plague outbreaks across the world, WHO’s website provides the following list of recent outbreaks in 21st century.


The Wild Canadian Year

Wild Canadian Year

Visit our website to watch the series online, discover extra behind-the-scenes stories and view Canada's nature scenes in 360. Visit Wild Canadian Year

From CBC Kids

The Nature of Thingies