Can You Still Get the Plague?

The bacteria responsible for the Black Death is still around, and there's no vaccine. Should you be worried about the disease that ravaged European populations in the Middle Ages?

Sabrina Stierwalt, PhD
4-minute read
Episode #353
The Quick And Dirty
  • Cases of plague still arise but are very rare
  • There is no vaccine to prevent plague but it is treatable with antibiotics
  • Basic precautions can help you easily avoid plague 

Plague is one of the deadliest diseases humans have ever faced—only smallpox is responsible for taking more lives. The origins of plague epidemics were once considered mysterious. That left people powerless to stop it as the disease ravaged populations across Europe during the Middle Ages, taking the lives of an estimated 25 million people.

In the mid 17th century, the plague claimed the lives of as much as one-fifth of the population of London. Victims were buried in hastily-made, unmarked, underground graves. When the underground train system was first built 200 years later, legend has it that engineers chose meandering routes for their tunnels in order to avoid these so-called plague pits. Evidence doesn’t back up this lore, though. There are no mentions of plague pits in the rail’s records. The meandering track lines are also easily explained by economics, for example, by avoiding private property to make construction cheaper.

Three cases of plague were reported this month—that's November of 2019—by hospitals in and near Beijing, China.

The source of the plague is no longer mysterious. We now know that the plague is an infection caused by the bacteria Yersinia pestis. But our plague legends persist in part because of the extreme devastation the disease caused. Plague is also not entirely a thing of the past. Three cases of plague were reported this month—that's November of 2019—by hospitals in and near Beijing, China. All three patients are from inner Mongolia where two fatal cases were already reported this year.

Globally, the World Health Organization recorded 3,248 cases of plague between 2010 and 2015. Those cases resulted in 584 deaths. So why isn’t the plague a thing of the past? And can you still catch it?

How do you catch the plague?

People usually catch the plague when they are bitten by fleas that have previously bitten infected rodents or by handling those rodents directly. Rodents affected by the plague are mostly found in rural areas in:

  • Asia
  • Africa (particularly in Madagascar and the Democratic Republic of the Congo)
  • South America (especially in Peru)
  • the United States

In the United States, cases have primarily been reported in New Mexico, Arizona, California, and Colorado.

What is the plague?

There are three main categories of the plague depending on what part of the body is predominantly infected.

Bubonic plague is the most common strain. Sufferers develop swollen and sensitive lymph nodes called buboes. Those swollen glands are sometimes as large as an egg around the groin, armpits, and neck.

Septicemic plague infects your bloodstream and can lead to the blackening (and thus death) of tissue in your extremities like your toes, fingers, and nose.

Pneumonic plague is the least common strain but the most deadly. It affects the lungs, which means it can be spread very easily from person to person through coughing.

If left untreated, bubonic plague, which makes up 80% of the cases of plague in the US, can turn into pneumonic plague.

The plague has a tendency to act fast and to be deadly. It was known as the Black Death in medieval times for a reason.

So what makes the plague different from other bacterial infections? Well, the plague has a tendency to act fast and to be deadly. It was known as “the Black Death” in medieval times for a reason. According to the World Health Organization, 30-60% of bubonic plague cases end in fatalities as well as 100% of pneumonic plague cases that aren’t treated swiftly.

The Center for Disease Control in the United States considers plague a “Category A” biothreat—the highest level threat—because it can be easily disseminated and transmitted from person to person, results in high mortality rates, causes public panic and social disruption, and would require special action from public health officials.

Why does the plague still persist?

When diseases only affect humans, they're easier to eradicate. We can keep records of where the cases are occurring and who may have been infected in the same outbreak.

But in the case of plague, animals also carry the disease. Low levels of plague continue to live in rodent populations. That means the disease has never fully disappeared. It won’t fully disappear unless we eradicate all of the rodent populations that are possibly infected. No small task.

How can you protect yourself from the plague?

There is no vaccine to prevent the plague. (Although, if people refuse to get vaccinated, a disease will re-emerge anyway. That's what we're seeing with the recent surge in measles cases.)

Fortunately, plague cases are extremely rare and can be treated effectively with antibiotics. There's a catch, though—a plague sufferer must be treated promptly because symptoms can progress rapidly. We rely mostly on the antibiotic streptomycin, although strains of the bubonic plague that are resistant to streptomycin have been seen in Madagascar.

Some of the recent cases of plague were caused by eating raw marmot kidneys, which is believed in some cultures to bring good health.

Some of the recent cases of plague, for example, were caused by eating raw marmot kidneys, which is believed in some cultures to bring good health. So, with some straightforward precautions, you can easily avoid contracting the plague.

The disease lives mostly in rural areas with poor sanitation or a large population of rodents. That includes rats, of course, but also mice, rabbits, squirrels, prairie dogs, chipmunks, and voles. If you visit such an area and get sick, check in with your doctor immediately. Keep rodents out of your home by getting rid of possible nesting places and keep your pet free of fleas. If you travel to a place at high risk for plague, use insect repellant and don’t handle any rodents.

Please note that archive episodes of this podcast may include references to Ask Science. Rights of Albert Einstein are used with permission of The Hebrew University of Jerusalem. Represented exclusively by Greenlight.

About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.