Can You Still Get Bubonic Plague Today?

Many people think bubonic plague is a disease of the past, but that’s not true. Although bubonic plague is rare in the U.S., with fewer than 12 cases annually, it is still around. Read more to learn about where plague still exists today, how it’s transmitted, and how it’s treated. 

What is bubonic plague?

Bubonic plague is a bacterial illness. There are three forms of plague: 

• Bubonic

• Pneumonic 

• Septicemic

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Of these, bubonic plague is the most common. 

In the early stages of bubonic plague, people feel feverish and tired. Then they develop swollen and tender lymph nodes, called “bubos,” from which the disease gets its name. Swollen lymph nodes can appear in the neck, armpit, or groin. They can be very large — up to 4 inches in length. These swollen nodes are so painful that people can find it hard to move. 

If left untreated, bubonic plague can quickly spread and infect other parts of the body. Bubonic plague can also progress to septicemic plague, which is a more serious form of plague. In septicemic plague, people may bleed internally while body parts such as fingers, toes, and the nose can necrose — or turn black and die. 

Before antibiotics existed, almost half of people who had plague died. Fortunately, that’s not the case anymore.

How is bubonic plague transmitted?

A bacteria called Yersinia pestis causes all three forms of plague. Yersinia pestis lives in rodents, like rats, and other small mammals. The bacteria can live in these animals without killing the animals in large numbers, so they continue to be a reservoir for plague. When fleas bite the animals that carry the bacteria, they also become infected. These fleas then bite people, causing them to become sick with bubonic plague. Often the lymph node that sits nearest to the bite site swells and becomes a “bubo.” 

In the past, scientists thought people couldn’t pass plague to one another. But new research suggests that people can spread the disease to others through body lice or human fleas, without the presence of animal fleas. One study estimated that every person with plague transmits the disease to two other people through lice or fleas. This is similar to the rate that people with COVID-19 transmit the coronavirus to others.

What animals carry bubonic plague?

Though plague is usually associated with rats, other small mammals can carry plague bacteria, including:

• Prairie dogs

• Chipmunks

• Moles

• Squirrels

• Woodland mice

These wild mammals are the major reservoir for plague bacteria in rural and semi-rural areas in the U.S. In 1924, a plague outbreak in Los Angeles caused plague bacteria to spread from urban rats to rural rats. From there, the bacteria spread to wild rodents and small mammals, where it still lives today. 

Where does bubonic plague still exist?

Plague is a worldwide concern. The World Health Organization (WHO) monitors the number of cases across the globe. Most cases occur in Central Asia and Africa. 

The western U.S. is also an established plague region. Specifically, plague bacteria is only found in mammals to the west of the 100th meridian — also known as “the plague line.” Arizona, New Mexico, and Colorado have the highest numbers of reported plague in the U.S., but plague exists in other western states, too.  

When was the last case of bubonic plague in the U.S.?

All types of plague are uncommon in the U.S. Over the last 20 years, 1 to 17 plague cases have occurred annually. Most recently, in July 2021, a 10-year-old resident of Colorado died from complications of plague. 

How do you diagnose bubonic plague?

Bubonic plague is diagnosed with a blood test or lymph node biopsy. Because plague progresses quickly, healthcare providers won’t wait for the results to come back before starting treatment .

Bubonic plague is rare in the U.S., so many healthcare providers won’t immediately think to test for it, especially if you live east of the 100th meridian. It’s important to let a healthcare provider know if you have recently traveled to a region where plague is common or if you have been bitten by fleas or handled wild animals.

How do you treat bubonic plague?

Fortunately, plague is curable with antibiotics. In the U.S., gentamicin and the fluoroquinolones, such as levofloxacin, ciprofloxacin, and moxifloxacin are the first-choice treatment. Usually people take these antibiotics for 2 weeks. In countries where these medications aren’t readily available, healthcare providers may use other antibiotics. 

How to protect yourself against bubonic plague 

Bubonic plague is rare. But if you live in the western part of the U.S. or are traveling to areas with plague, you should:

• Avoid wild mammals, including small rodents.

• Remove things from your property that can encourage small mammals to take residence, like food, brush, and firewood piles.

• Wear gloves if handling or skinning wild animals. 

• Use DEET or appropriate bug spray if you are camping, hiking, or working outdoors to prevent flea bites. 

• Ensure pets are flea free by using appropriate flea-control products.

• Let your healthcare provider know if you were exposed to persons or animals with plague so that you can get prophylactic treatment.

A bubonic plague vaccine was available during the 20th century. U.S. military service members fighting in Vietnam got the vaccine, but it caused serious reactions and offered only modest protection. The vaccine was discontinued and no vaccine is currently available. However, scientists working at the WHO are trying to develop one. 

Why trust our experts?

Written by:

Ronald W. Dworkin, MD, PhD

Ronald W. Dworkin, MD, is a board-certified anesthesiologist who has been practicing anesthesiology in a community hospital for 30 years. He has taught in the honors program at George Washington University for over 10 years and works as a senior fellow at the Hudson Institute.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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