Bubonic Plague

Bubonic plague is an infection spread mostly to humans by infected fleas that travel on rodents. Called the Black Death, it killed millions of Europeans during the Middle Ages. Prevention doesn’t include a vaccine, but does involve reducing your exposure to mice, rats, squirrels and other animals that may be infected.


What is the bubonic plague?

Plague is an infectious disease caused by a specific type of bacterium called Yersinia pestis. Y. pestis can affect humans and animals and is spread mainly by fleas. Bubonic plague is one type of plague. It gets its name from the swollen lymph nodes (buboes) caused by the disease. The nodes in the armpit, groin and neck can become as large as eggs and can ooze pus.

The other types of plague are:

  • Septicemic plague, which happens when the infection goes all through the body.
  • Pneumonic plague, which happens when lungs are infected.


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Is this the same bubonic plague that killed so many people during medieval times?

Yes. Bubonic plague deaths exceeded 25 million people during the fourteenth century. This was about two-thirds of the population in Europe at the time. Rats traveled on ships and brought fleas and plague with them. Because most people who got the plague died, and many often had blackened tissue due to gangrene, bubonic plague was called the Black Death. A cure for bubonic plague wasn’t available.

Does the bubonic plague still exist?

There have been other episodes of bubonic plague in world history apart from the Black Death years (1346-1353). Bubonic plague still occurs throughout the world and in the U.S., with cases in Africa, Asia, South America and the western areas of North America. About seven cases of plague happen in the U.S. every year on average. Half of the U.S. cases involve people aged 12 to 45 years.

In the U.S., most plague cases in people happen in two areas: Northern New Mexico, northern Arizona and southern Colorado, and another area involving California, southern Oregon and western Nevada.


Symptoms and Causes

What are the symptoms of bubonic plague?

Bubonic plague symptoms include:

  • Sudden high fever and chills.
  • Pains in the areas of the abdomen, arms and legs.
  • Headaches.
  • Large and swollen lumps in the lymph nodes (buboes) that develop and leak pus.

Symptoms of septicemic plague may include blackened tissue from gangrene, often involving the fingers or toes, or unusual bleeding. People with pneumonic plague may have additional trouble breathing and may cough up blood. Sometimes there are symptoms like nausea or vomiting.

What causes bubonic plague?

Bubonic plague is a type of infection caused by the Yersinia pestis (Y. pestis) bacterium which is spread mostly by fleas on rodents and other animals. Humans who are bitten by the fleas then can come down with plague. It’s an example of a disease that can spread between animals and people (a zoonotic disease).

It can be noted that cats in particular are vulnerable to plague and can be infected by eating sick rodents. These cats can pass droplets infected with plague to their owners or to the veterinarians that treat them.

Person-to-person spread is unlikely, except in rare cases of someone who has pneumonic plague (infected lungs) spreading plague through droplets sprayed into the air. In other rare cases, people have been infected with pneumonic plague by their dogs or cats.


Diagnosis and Tests

How is bubonic plague diagnosed?

To diagnose bubonic plague, your healthcare provider will order blood or tissue sample tests. The samples will be sent to the lab for testing to see if Y. pestis is present.

Management and Treatment

How is bubonic plague treated?

The bubonic plague can be treated and cured with antibiotics. If you are diagnosed with bubonic plague, you’ll be hospitalized and given antibiotics. In some cases, you may be put into an isolation unit.

Antibiotics that treat bubonic plague include:

  • Ciprofloxacin, levofloxacin and moxifloxacin.
  • Gentamicin.
  • Doxycycline.

What happens if bubonic plague isn’t treated?

Bubonic plague can be fatal if it’s not treated. It can create infection throughout the body (septicemic plague) and / or infect your lungs (pneumonic plague.) Without treatment, septicemic plague and pneumonic plague are both fatal.


How can bubonic plague be prevented?

You can take the following steps to prevent bubonic plague:

  • Make your home and yard inhospitable to rodents (mice, rats, squirrels) and other wild animals. Don’t leave places for them to hide or food for them to eat. This means cleaning up clutter, brush and other items and being careful when feeding animals.
  • Use flea control products for your pets, especially those who are allowed to roam freely. Take sick pets to the veterinarian immediately.
  • Don’t let pets who roam freely sleep in your bed.
  • Wear protective clothing — especially gloves — if you handle dead animals.
  • Use insect repellent if you go into wooded locations or other places that may expose you to fleas. Look for repellents that use DEET or permethrin.

Is there a bubonic plague vaccine?

In the U.S., there is currently no bubonic plague vaccine. In other locations, a vaccine is available only to people who have a high exposure to the plague because of their jobs.

Outlook / Prognosis

What is the outlook for someone with bubonic plague?

If you’ve had bubonic plague and been treated for it, your outlook is very good. Symptoms usually develop two to six days after exposure. The best recovery happens if you are treated within 24 hours of developing symptoms. You’ll probably feel better after one to two weeks. However, untreated bubonic plague can be fatal.

Living With

When should I contact my healthcare provider regarding bubonic plague?

If you develop symptoms of plague, such as high fever, pain and swollen lymph nodes, you should contact your healthcare provider. This is especially true if you have been exposed to flea bites. This is also true in the rare case that you have been exposed to someone who has bubonic plague.

A note from Cleveland Clinic

Bubonic plague may seem like a part of the past, but it still exists today in the world and in rural areas of the U.S. The best way to prevent getting plague is to avoid the fleas that live on rodents such as rats, mice and squirrels. The fleas can also live on chipmunks and rabbits. Take care to protect your pets and yourself from fleas and the possible infections they can carry. Make sure to contact your healthcare provider if you develop high fever, chills and especially symptoms like swollen and painful lymph nodes.

Medically Reviewed

Last reviewed on 06/17/2021.

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