Plague

Overview

What is plague?

Plague is an illness you get from the bacterium Yersinia pestis (Y. pestis). Plague is a zoonotic disease, which means you can get it from animals and they can get it from you. This disease usually spreads through bites from fleas that previously bit an infected animal.

There are three types of plague. Which type you have depends on where in your body Y. pestis ends up. Bubonic plague infects your lymph nodes, septicemic plague is in your blood and pneumonic plague affects your lungs.

What is the plague called today?

Today we still use the word “plague” to mean illness caused by Yersinia pestis. Usually, we also call it by the specific type of plague it is — bubonic, septicemic or pneumonic.

Does plague still exist?

Yes, plague still exists. It’s most common in parts of Africa, but a few cases are reported in Asia, South America and the U.S. every year.

What are the three plagues?

The three types of plague — bubonic, septicemic and pneumonic — are each named for the part of your body that gets infected by Y. pestis.

Bubonic plague

Bubonic plague is the most common form of plague. It’s also the most survivable. With quick antibiotic treatment, you have about a 95% chance of recovering from bubonic plague.

Bubonic plague makes one or more lymph nodes painful and swollen. The affected lymph nodes are usually near where an infected flea bit you.

Septicemic plague

When Y. pestis gets into your blood, you have septicemic plague. It destroys your tissues, leading to gangrene and organ failure. You can get septicemic plague from:

  • A flea bite.
  • Body fluids of an infected animal getting into a break in your skin.
  • Y. pestis moving to your blood from another part of your body (secondary infection).

Pneumonic plague

You get pneumonic plague when Y. pestis bacteria gets into your lungs. It’s the least common and most dangerous type of plague.

Pneumonic plague can spread from person to person through coughing and sneezing, just like the common cold. You can also get it from close contact with infected animals or from bacteria moving to your lungs from another part of your body (secondary infection).

Pneumonic plague causes severe pneumonia and respiratory failure. If not treated, most people with pneumonic plague die within days.

What is the difference between bubonic and pneumonic plague?

Bubonic plague and pneumonic plague are caused by the same bacterium, Y. pestis. Bubonic plague is a bacterial infection in your lymph nodes and pneumonic plague is a bacterial infection in your lungs.

Who does plague affect?

Plague mostly affects people living in a few countries in Africa, but cases are also reported in the Americas and Asia every year. It’s most common in Madagascar and the Democratic Republic of Congo.

In the U.S., you’re more likely to get plague in rural areas of western states. You’re at higher risk if you work with animals in an area where plague is found.

How common is plague?

While it still exists, plague is extremely rare now. Worldwide, 1,000 to 2,000 people are diagnosed with plague every year. Only about seven cases are reported in the U.S. each year.

How does plague affect my body?

When Y. pestis enters your body, it hides from your immune system, allowing it to multiply and spread out. When it gets into cells, it releases a toxin to kill the cell.

Y. pestis can infect your lymph nodes (bubonic plague), causing large swellings called buboes. If it gets in your blood (septicemic plague), it can damage your organs. If it gets into your lungs (pneumonic plague), it can cause severe inflammation and respiratory failure.

What was the deadliest plague?

The deadliest plague killed millions of people in Europe, Asia and North Africa in the mid-1300’s. Hunger and poor sanitation made people vulnerable to sickness, and it spread to different countries through trade routes.

It’s usually what people mean when they talk about “the plague.” This plague also is sometimes referred to as the "Black Death."

Symptoms and Causes

What are the symptoms of plague?

Some symptoms of plague happen in all types and some depend on whether you have bubonic, septicemic or pneumonic plague.

Symptoms of plague include:

What does plague look like?

Plague looks different depending on which part of your body is infected. Septicemic plague can cause gangrene, which destroys your tissues. Your fingers, hands, toes, feet or other body parts might turn black.

If you have bubonic plague, you’ll have one or a few very large, noticeable lymph nodes. Many people use medieval artwork to show bubonic plague, but the people in the artwork are usually shown with sores all over. This isn’t what plague looks like. (The iconic artwork likely shows smallpox or leprosy.)

What causes plague?

The bacterium Yersinia pestis (Y. pestis) causes plague. Rats and other animals carry Y. pestis, but humans usually get infected by being bitten by fleas or lice carrying the bacteria. Y. pestis gets into your lymph nodes, bloodstream or lungs and makes you sick.

How does plague spread?

Y. pestis, the bacterium that causes plague, can spread to people from animals or other people. You can get plague:

  • By getting bitten by fleas or lice. Fleas bite rats or other animals infected with pestis, then bite you.
  • Directly from an infected animal. You can get infected with Y. pestis by touching body fluids or tissues of an infected animal.
  • From another person. If someone has Y. pestis in their lungs (pneumonic plague), you can get infected if they cough or sneeze on you.

Animals can also get plague from other animals.

What animals carry plague?

Most people think of rats as the only carriers of plague, but many animals carry and spread the disease. Which animals are more likely to have plague is different depending on where you live. Research shows plague can affect:

  • Rodents (including rats, mice, prairie dogs, ground squirrels, gerbils and guinea pigs).
  • Other small mammals.
  • Pet dogs and cats.
  • Deer.
  • Camels.

Is plague contagious?

Bubonic and septicemic plague are not contagious, but pneumonic plague is. Pneumonic plague can spread from person to person through coughing, sneezing and close contact.

Is plague a virus?

No, plague isn’t a virus. Plague happens because of the bacterium Yersinia pestis.

Diagnosis and Tests

How is plague diagnosed?

The most common sign of bubonic plague is a swollen and painful lymph gland called a bubo. Your provider may suspect plague if you have a flea bite or a bubo.

Make sure you mention to your provider if you:

  • Live in or have recently visited an area where there are plague infections.
  • Have been bitten by fleas.
  • Have handled animals that could be infected.
  • Have one or more painful lymph nodes.

What tests are done to diagnose plague?

To diagnose plague, your healthcare provider will take a sample of your blood, your spit (mucus or phlegm) or fluid from a lymph node. They’ll send your sample to a lab to look for signs of Y. pestis bacterium.

Management and Treatment

How is plague treated?

Plague needs to be treated with antibiotics right away. Your healthcare provider will give medication to you either through your veins (IV) or in a pill to take. Depending on your symptoms and risk, you may start antibiotics even before your provider has your test results.

What medications are used to treat plague?

You take antibiotics by mouth or through your veins to treat plague. Your healthcare provider might prescribe one or more of these antibiotics:

Prevention

How can I prevent plague?

You can reduce your risk of plague by avoiding flea bites and being careful around animals that could be infected.

  • Clear piles of brush, wood, trash or other places where wild animals might make a home. Don’t leave pet food out or feed wild animals.
  • Wear bug spray with DEET.
  • Ask your pet’s veterinarian how to prevent fleas. Pet dogs and cats can spread plague.
  • Wear gloves if you have to handle animals that could be infected. This includes living and dead animals.
  • If you live in an area with plague, don’t let your pets roam free outside.
  • If you think something exposed you to plague, ask your healthcare provider whether you should take antibiotics to prevent getting sick.

Is there a vaccine for plague?

Vaccines aren’t widely used to protect against plague. Scientists are currently working on creating more effective plague vaccines.

Outlook / Prognosis

What should I expect if I have plague?

You need to get treated immediately if you have plague. While antibiotics work well, you have the best chance of getting better if you start taking them within 24 hours of noticing symptoms. You may be given extra oxygen or other treatments to manage your symptoms.

How long does plague last?

If treated, you’ll probably feel better in a week or two. Buboes from bubonic plague might take a few weeks to go away.

Complications of plague

Many complications of plague happen quickly and are life-threatening, including:

  • Tissue death and loss of limbs from gangrene.
  • Inflammation of the lining of the brain (meningitis).
  • Organ failure.
  • Respiratory failure.

How do you survive the plague?

Immediate treatment with antibiotics will help you survive the plague. With quick treatment, about 90% of people with all forms of plague survive.

What’s the mortality rate for plague?

Without treatment, plague is nearly always fatal. With treatment, there’s a 5-15% mortality (death) rate for bubonic plague and around a 50% mortality rate for pneumonic and septicemic plague.

Living With

When should I see my healthcare provider about plague?

Contact your healthcare provider for immediate medical attention if you:

  • Think something exposed you to plague.
  • Live in or recently traveled to areas where plague exists and have symptoms of plague.

What questions should I ask my doctor?

  • If I think I’ve been exposed to plague, should I take antibiotics?
  • Will I stay in the hospital or treat myself at home?
  • What new or changing symptoms should I look out for?

Frequently Asked Questions

What historic pandemics were caused by the plague?

There were three infamous plague pandemics in history:

  • The Plague of Justinian started around 541 and had several waves of illness. It’s hard to get an accurate number, but it’s thought that tens of millions of people died during this pandemic.
  • The Black Death started in 1348. About 25 million people died in Europe during the Black Death.
  • The third plague pandemic spread to every continent except Antarctica. It killed around 12 million people in India and China alone.

A note from Cleveland Clinic

Millions of people died in plague pandemics in the past. It still exists today, but thanks to modern sanitation and antibiotics, very few people die from it — though it’s critical that you receive treatment immediately. If someone tells you they’re “avoiding it like the plague,” feel free to congratulate them on their safe animal handling and flea management strategies.

Last reviewed by a Cleveland Clinic medical professional on 08/22/2022.

References

  • Chung LK, Bliska JB. Yersinia versus host immunity: how a pathogen evades or triggers a protective response. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4755919/) Curr Opin Microbiol. 2016;29:56-62. Accessed 8/22/2022.
  • Clinical Key. Clinical Overview: Plague. (https://www-clinicalkey-com.ccmain.ohionet.org/#!/content/clinical_overview/67-s2.0-eaa6ab43-b282-495c-9731-fd4c2b3179a9) Accessed 8/22/2022.
  • Glatter KA, Finkelman P. History of the Plague: An Ancient Pandemic for the Age of COVID-19. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7513766/) Am J Med. 2021;134(2):176-181. Accessed 8/22/2022.
  • Prentice MB. Plague and Other Yersinia Infections. In: Loscalzo J, Fauci A, Kasper D, et al. eds. Harrison’s Principles of Internal Medicine 21e. McGraw Hill; 2022. Accessed 8/22/2022.
  • Sun W, Singh AK. Plague vaccine: recent progress and prospects. (https://www.nature.com/articles/s41541-019-0105-9) npj Vaccines 2019 Feb; 4(11). Accessed 8/22/2022.

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