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."