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The Black Death Has Resurfaced In 2024: Here Are 5 Things You Need To Know About The Bubonic Plague

Yersinia pestis bacteria causes bubonic plague in animals and humans Photo: Getty Images

Yersinia pestis bacteria causes bubonic plague in animals and humans Photo: Getty Images

The bubonic plague has emerged in Oregon for the first time in almost ten years.

Last week, health officials in the central region of Oregon reported that a person likely contracted the bubonic plague from their cat. Physicians promptly diagnosed the illness and administered antibiotics to the individual. Additionally, they traced and treated all contacts of the person and their cat as a precautionary measure. Consequently, authorities anticipate no further spread of the disease or fatalities.

The fundamentals of the plague are familiar to most individuals.

It is widely understood that during the 14th century, the plague resulted in the Black Death, a pandemic that potentially claimed 30% to 50% of the population in certain European regions, with an estimated death toll surpassing 50 million. Additionally, people are aware that the disease is transmitted through rodents and the fleas that bite them.

However, in the past decade, scientists have made significant advancements in understanding the plague and its effects on the human body. Here are several key revelations about the plague.

People of European Descent may Possess one (or two) Genes that offer Protection against the Plague

During the outbreak of the Black Death in Europe and the United Kingdom in the 1300s, it is believed that the disease not only reshaped society but also influenced the evolution of the human genome.

According to a study published in 2022, survivors of the plague in London and Denmark exhibited mutations in their genomes that conferred resistance to the plague-causing pathogen, Yersinia pestis.

Researchers identified four advantageous mutations in the genomes of these individuals. One of these mutations was estimated to increase the likelihood of surviving the plague by 40%, marking it as the most significant evolutionary advantage ever documented in humans for a single mutation, as per researchers interviewed by NPR.

These beneficial mutations were passed down to subsequent generations by survivors, resulting in many Europeans and Americans of European descent carrying these genetic variations today.

However, it is suggested that these advantageous genes may come with a trade-off. For instance, one of the mutations is associated with an increased susceptibility to autoimmune diseases like Crohn's disease.

Following years of Dormancy, the Plague has the Potential to Resurface in any Given Region

Annually, the world records between 200 to 700 cases of plague, although a significant number of cases likely remain undetected. The majority of these occurrences are concentrated in specific areas globally, with hot spots like Madagascar contributing to approximately three-quarters of reported cases. In the United States, fewer than a dozen cases are typically documented each year, primarily in the West.

However, the Yersinia pestis bacterium can manifest almost anywhere, including regions believed to have eradicated the disease or where it hasn't been observed for decades.

An instance of this resurgence occurred in Libya. After a 25-year absence of recorded plague cases, the disease reappeared in 2009. Initially, scientists speculated that the pathogen may have been introduced by an individual or animal from a neighboring country. However, analysis of the bacteria's DNA yielded a surprising revelation: the strain of plague in Libya closely resembled Y. Pestis originating from Central Asia thousands of years ago, distinct from strains found in neighboring countries.

"We think the plague is extinct in these places, but it's not," microbiologist Elisabeth Carniel at the Institut Pasteur told NPR for a January 2013 story. "The plague is still there."

The whereabouts of the plague during periods of inactivity remain elusive, with speculation suggesting that it circulates undetected among rodents and the fleas they harbor. It's plausible that the bacterium exists at such low levels that it remains unnoticed for decades.

Even in the Presence of Antibiotics, one form of the Plague can Result in an Exceptionally High Fatality Rate

The plague presents itself in various forms depending on the body part invaded by the bacteria. When a person is bitten by a flea, they typically develop bubonic plague, characterized by swollen and painful lymph nodes known as buboes.

The term "bubonic" originates from the Greek word "boubon," meaning groin, as some individuals experience swollen lymph nodes in their groin area.

Diagnosis of the disease can be confirmed by extracting a sample from the person's blood or lymph nodes and submitting it to a laboratory for testing.

However, if the bacteria spread to the lungs, it can lead to pneumonic plague. Unlike bubonic plague, there are often no distinctive signs of the plague in this case, according to the Centers for Disease Control and Prevention.

Pneumonic plague poses a significantly greater risk, as explained by medical entomologist Adelaide Miarinjara from Emory University. "It transmits pretty easily between people because it spreads through droplets, almost like COVID spreads."

Moreover, people can die more quickly with pneumonic plague due to its swift progression. "The key here is early diagnosis. If people aren't expecting it or don't seek treatment, they can die."

In 2017, Madagascar experienced a large outbreak of pneumonic plague when an individual from a rural area introduced the disease to the coastal city of Toamasina. This city had not encountered a case of the plague in nearly a century, according to Miarinjara, who was present in Madagascar at the time.

The disease was transmitted via public transportation, resulting in over 2,400 suspected cases, including nearly 1,900 cases of pneumonic plague. A study estimated that approximately 25% of individuals with confirmed cases succumbed to the disease during this outbreak.

Plague Bacteria induce Vomiting in Fleas

In the western United States, various rodents, including chipmunks, squirrels, and prairie dogs, can harbor the plague bacteria, which they can transmit to humans through bites and scratches.

However, most of the time, rodents—and often humans—contract Y. Pestis from a flea bite. Scientists now have a comprehensive understanding of how the flea transmits the bacteria during this process.

When a flea becomes infected, the plague bacteria reside within the insect's gut. Here, the bacteria produce a viscous, adhesive substance known as a biofilm. This film forms a small plug in the flea's throat, making it difficult for the insect to swallow. Consequently, when the flea bites an animal, it essentially regurgitates the biofilm—along with the plague bacteria—into the animal's bloodstream.

Microbiologist Viveka Vadyvaloo explained this process in a 2021 interview with the Washington State University Insider, stating, "You can imagine, you have something stuck in your throat and you try to take in some water but can't. You will vomit all that water out, and that's what happens to the flea. The blocked, starving flea will repeatedly bite its rodent or human host, creating more opportunities for infection."

The Black Death gave rise to the word "Quarantine"

The term "quarantine" originated from the Black Death pandemic, during which the city-state of Dubrovnik, now part of Croatia, implemented what is believed to be the first state-mandated isolation measure.

At that time, Dubrovnik, a prosperous merchant city situated along the Adriatic Sea, aimed to prevent the spread of bubonic plague. To achieve this, city authorities enforced a policy requiring visitors to spend 40 days on a remote island outside the city before being allowed ashore.

This waiting period was referred to as "quarantino," derived from the Italian word for "40."

According to Ivana Marinavić, head of educational programs at the Lazarettos of Dubrovnik, "the first quarantine was pretty much improvised." The Lazarettos, constructed specifically for quarantine purposes, were among the first buildings built for this purpose.

Breaking quarantine during the plague carried severe consequences. As Marinavić stated, "Torture, or cutting your nose or your ears off," were among the punishments imposed for non-compliance.

So You Think You Know All About The Plague?

The bubonic plague has cropped up in Oregon for the first time in nearly a decade.

This time a person likely caught it from their cat, health officials in the central part of the state said last week. Doctors identified the disease quickly and treated the person with antibiotics. They also tracked down all the person's contacts (and the cat's contacts) and gave them medication as well. So they don't expect the disease to spread or cause any deaths.

Most people know the basics about the plague.

They know that in the 14th century it caused the Black Death — the pandemic that may have killed 30% to 50% of the population in parts of Europe, with an estimated death toll of at least 50 million. And they know that it spreads through rodents and the fleas that bite them.

But over the last decade, scientists have learned way more about the plague and how our bodies respond to it. Here are a few plague revelations.

People of European descent may carry a gene (or two) that protects them against the plague

When the Black Death spread through Europe and the United Kingdom back in the 1300s, the disease changed more than society: It also likely altered the evolution of people's genome.

A study, publishedin 2022, found that people who survived the plague in London and Denmark had mutations in their genomes that helped protect them against the plague pathogen, Yersinia pestis.

Altogether, the researchers found four helpful mutations in people's genomes. The advantage was quite substantial. One mutation boosted people's chance of surviving the plague by 40%, the study estimated. That's the biggest evolutionary advantage ever recorded in humans for a single mutation, researchers told NPR.

Survivors passed those mutations to their descendants, and many Europeans — as well as Americans of European descent — still carry those mutations today.

But these helpful genes have likely come at a cost. One of the mutations increases a person's risk of autoimmune diseases, such as Crohn's disease.

After decades of silence, the plague can reemerge in a region

Each year, the world records 200 to 700 cases of plague, although many cases likely go undetected. Most of these cases occur in hot spots around the globe, such as Madagascar, which accounts for about three-quarters of the world's cases. The U.S. Typically records fewer than a dozen cases each year, with most of them occurring in the West.

But really, Y. Pestis can crop up almost anywhere, even in places where scientists think they've eradicated the disease or haven't seen it in decades.

That's exactly what happened in Libya. After no record of plague cases for 25 years, the disease appeared again in 2009. At first, scientists thought perhaps somebody — or an animal — had brought in the pathogen from a neighboring country. But when they decoded the bacteria's DNA, it revealed a surprise: The plague in Libya most closely resembled Y. Pestis that originated in Central Asia thousands of years ago (and didn't look like the bacteria found in a neighboring country).

"We think the plague is extinct in these places, but it's not," microbiologist Elisabeth Carniel at the Institut Pasteur told NPR for a January 2013 story. "The plague is still there."

So where is it hiding? It's likely circulating, undetected, in rodents and the fleas they carry. Maybe the bacterium is at such low levels that it goes undetected for decades.

Even when antibiotics are available, one form of the plague can have an extremely high fatality rate

The plague comes in several versions, depending on which body part the bacteria invade. When a flea bites a person, the individual typically develops what's called bubonic plague. In this case, the telltale sign is one or more swollen and painful lymph nodes, known as buboes. (The word "bubonic" comes from the Greek boubon, which means groin, because some people have swollen lymph nodes in their groin.) Doctors can diagnose the disease by taking a sample from the person's blood or lymph nodes and then submitting the sample to a lab for testing.

But when the bacteria spread to the lungs, this can cause what's called pneumonic plague. In this case, there's often no telltale sign of the plague, according to the Centers for Disease Control and Prevention.

This version is much more dangerous, says medical entomologist Adelaide Miarinjara at Emory University. "It transmits pretty easily between people because it spreads through droplets, almost like COVID spreads."

And people can die more quickly with pneumonic plague, she adds, because the disease progresses more rapidly. "The key here is early diagnosis. If people aren't expecting it or don't seek treatment, they can die."

In 2017, Madagascar suffered a large outbreak of pneumonic plague when a person from a rural part of the country brought the disease to the coastal city of Toamasina. That city hadn't seen a case of the plague in nearly a century, says Miarinjara, who was in Madagascar at the time. "A person transmitted the disease on public transportation," she says.

The country recorded more than 2,400 suspected cases, including nearly 1,900 cases of pneumonic plague. One study estimated that about 25% of people with confirmed cases died in this outbreak.

Plague bacteria make fleas vomit

In the Western U.S., all sorts of rodents can carry the plague, including chipmunks, squirrels and prairie dogs. And they can transmit the bacteria to humans through bites and scratches. (When I was in college in Pasadena, Calif., back in the early 1990s, a classmate caught the plague from a squirrel she was feeding.)

But most of the time, rodents — and often people — catch Y. Pestis from a flea bite. And scientists now have a detailed understanding of how the flea transmits the bacteria during this bite.

When a flea itself is infected, the plague bacteria live inside the insect's gut. There, the bacteria create a gooey, sticky material, called a biofilm. This film forms a little plug in the flea's throat, making it hard for the insect to swallow. So when the flea bites an animal, instead of swallowing the animal's blood, the flea essentially vomits the biofilm — along with the plague bacteria — into the animal's blood.

"You can imagine, you have something stuck in your throat and you try to take in some water but can't. You will vomit all that water out, and that's what happens to the flea," microbiologist Viveka Vadyvaloo told the Washington State University Insider in 2021. "The blocked, starving flea will repeatedly bite its rodent or human host, creating more opportunities for infection."

The Black Death gave rise to the word "quarantine"

The idea of isolating, or quarantining, sick people dates back at least 3,000 years. The Book of Leviticus in the Bible mentions how to isolate people with leprosy.

But the word "quarantine" itself arose during the Black Death, when the city-state of Dubrovnik, now part of the country of Croatia, enacted what is likely the first state-imposed isolation.

At the time, Dubrovnik was a wealthy merchant city along the coast of the Adriatic Sea. City leaders wanted to keep the bubonic plague out. So they began to force visitors to wait for 40 days on a remote island outside the city before coming ashore.

They called the wait quarantino, from the Italian word for "40."

"The first quarantine was pretty much improvised," Ivana Marinavić, the head of educational programs at the Lazarettos of Dubrovnik, told NPR in 2021. The Lazarettos were the first buildings ever constructed for the sole purpose of quarantining.

If you broke the quarantine during the plague, the consequences were severe. "Torture, or cutting your nose or your ears off," Marinavić told NPR.

Copyright 2024 NPR. To see more, visit https://www.Npr.Org.

Yes, There Is A Treatment For Bubonic Plague

An Oregon resident's bubonic plague infection led to questions about vaccines and the ability to treat the disease that was once known as the "black death."

Credit: methaphum - stock.Adobe.Com

An Oregon resident was recently infected with bubonic plague, marking the state's first known case of the illness in nearly a decade. The person likely contracted the disease from a pet cat, public health officials said.  

Many people have likely heard the bubonic plague referred to as the "black death," a pandemic of the disease that killed an estimated 50 million people in Europe during the 14th century. 

The confirmed case in Oregon drew fearful responses from some people on social media and left others wondering if there is a treatment for the bubonic plague. 

THE QUESTION

Is there a treatment for the bubonic plague?

THE SOURCES

THE ANSWER

Yes, the bubonic plague is treated with antibiotics. 

WHAT WE FOUND

Plague is a disease caused by the Yersinia pestis (Y. Pestis) bacteria that can infect rodents, some other animals and people. People usually get the plague when they are bitten by a flea that is infected with the bacteria, according to the Centers for Disease Control and Prevention (CDC).

There are three types of plague: bubonic (which causes swelling of the lymph nodes), septicemic (which occurs when plague bacteria multiply in the bloodstream) and pneumonic (which affects the lungs). Bubonic plague is the "most common" and "most survivable" form, the Cleveland Clinic says, but the disease can be fatal if left untreated.

Antibiotic treatment for the plague usually begins as soon as a health care provider suspects a person has the disease, according to the CDC and Mayo Clinic. 

That's because people with the plague have the best chance of getting better if they start taking antibiotics within 24 hours of developing symptoms, the Cleveland Clinic says. A person who receives quick antibiotic treatment has a 95% chance of recovering from the bubonic plague, according to the health care system. 

The Mayo Clinic says common antibiotics that may be used to treat plague include gentamicin, doxycycline, ciprofloxacin, levofloxacin, moxifloxacin and chloramphenicol. 

While the bubonic plague is treatable, a vaccine is not currently available in the U.S. In other areas of the world, a vaccine is available only to people who have high exposure to the plague because of their job, according to the Cleveland Clinic.

Human plague cases are scarce in the U.S., with an average of seven reported each year in recent decades, according to the CDC. Human-to-human transmission of the bubonic plague in particular is also rare, the World Health Organization says.

Symptoms of bubonic plague and recovery time

Symptoms of bubonic plague include sudden high fever and chills, headache, weakness, pain in the abdomen, arms and legs, and large, swollen lymph nodes called buboes that leak pus, the CDC and Cleveland Clinic say.

To definitively diagnose plague, a person's blood or tissue sample tests will be sent to a laboratory to look for signs of the Y. Pestis bacteria.

A person who is treated for the plague will usually feel better in a week or two, though the buboes from bubonic plague might take a few weeks to go away, the Cleveland Clinic says. 

If bubonic plague isn't treated, it can lead to infection throughout the body with septicemic plague or infection in your lungs with pneumonic plague. Both of these diseases are often fatal without treatment.

Pneumonic plague is the "least common and most dangerous type of plague," the Cleveland Clinic says. 

How people can protect themselves from the plague

The CDC says human plague usually occurs in areas where the bacteria are present in wild rodent populations. 

People can reduce their risk of plague by avoiding flea bites and being careful around animals that might be infected.

Some tips from the Cleveland Clinic to reduce your risk include: 

Clearing 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.

Wearing bug spray with DEET.

Asking your pet's veterinarian how to prevent fleas. Dogs and cats can spread plague.

Wearing 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.

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