Human Case of the Plague Confirmed in Colorado: Why 'The Black Death' Lingers

When you hear of the plague or black death, what image does it conjure up? One of medieval Europe, full of rats, with poor sanitation, terrible hygiene, and constant disease? You would be right, of course—and wrong. What is referred to as 'the plague' is still around today—although infections in humans are luckily rare.

Earlier this year, a person in Oregon was diagnosed with the state's first case of the plague in eight years; in July, another person, this time in Colorado, contracted the disease between the 1970s and 2000; there were, on average, seven reported cases each year.

Understanding Bubonic Plague

More often referred to as the 'Black Death' or simply 'the plague,' bubonic plague is technically an infectious disease caused by a specific type of bacterium called Yersinia pestis. This bacteria can affect both humans and animals. The name bubonic comes from the swollen lymph nodes or buboes caused by infection.

Yersinia pestis is a nasty bacteria that isn't actually transported from human to human; it uses the common flee as an intermediary. During medieval times, fleas were abundant and lived on humans, rats, and other animals, easily spreading. When a flea-carrying Yersinia pestis bites a human, the bacteria travel through the lymphatic system to the nearest lymph node, where it can begin replicating.

Having this harmful bacteria replicate in the lymph nodes causes big problems. Normally, the lymphatic system moves fluid around the body. A lot of this fluid is cleaned and pumped inside lymph nodes. In the later stages of the infection, the inflamed lymph nodes can become open sores filled with pus, functioning poorly. The disease can progress quite quickly to infect the lungs, resulting in pneumonic plague, a more severe form of the disease.

Pneumonic Plague

Once the Yersinia pestis bacteria has made it to the lungs, this leads to severe respiratory symptoms. This form of the plague is characterized by fever, chest pain, and a cough that produces bloody or watery sputum. The pneumonic plague is the most severe type of plague because it can rapidly lead to respiratory failure and death if not treated promptly—which was most cases in the Middle Ages. In many cases, the disease progresses from untreated bubonic as the bacteria spread to the lungs. The onset of symptoms is often sudden, and the condition can deteriorate quickly, making speedy medical assistance critical for a good prognosis.

Thanks to public health and sanitation, interventions are usually quick, which means the plague is no longer the threat it was in past centuries. We've gone from physicians who didn't know how to cope with the plague and used bloodletting and prayers to "heal" people to medical professionals today being able to complete online degrees like direct entry MSN programs and create vaccines and provide treatment for a range of medical concerns.

Plague Across the World

This is far from an American issue; as with many common diseases, they often linger in the third world. In parts of Africa, like Madagascar and some rural areas in the Democratic Republic of Congo and Tanzania, the plague persists and causes regular outbreaks. Limited healthcare access in these areas means the disease can spread quickly before proper treatment is available.

Local conditions, including high rodent populations and flea vectors, contribute to the ongoing presence of the plague. International efforts aim to improve surveillance, diagnostics, and treatment access to manage and reduce the disease's impact. This global issue highlights the need for continued cooperation and investment in healthcare to address the plague effectively.

Why It Lingers

In recent times, multiple outbreaks have led authorities to research how we can eradicate this disease. In 1894, what is referred to as the third plague pandemic made its way to Hong Kong. Two scientists, Alexandre Yersin and Kitasato Shibasaburō, obtained samples of the virus and discovered Yersinia pestis at similar times. Since then, scientists have tracked the spread of this bacteria around the world and found that it is alarmingly common in fleas around the world.

Luckily, living standards have improved around the world; in the US, we have good hygiene in public and private places, pets are kept up with vaccines and flea checks, and, importantly, rats are far less common.

Eradication Efforts

Being protected by hygiene is all good and well, but wouldn't removing the threat entirely like we did with smallpox and polio would be nice? The problem is that the later diseases are transmitted purely from human to human. Plague has large animal reservoirs where it can hide for years before infecting one person.

The second option that comes to mind is a vaccine. After all, vaccines have been effective for a whole host of diseases. Currently, two types of plague vaccines: the live-attenuated vaccine and the killed-whole-cell vaccine (KWCV) variant made from heat-killed bacteria. Due to safety concerns, the live-attenuated vaccine still retains some virulence or availability to damage and is not commercially available for human use. Meanwhile, the KWCV provides protection against bubonic plague but is ineffective against the pneumonic form. Its short duration of immunity and potential adverse effects have driven researchers to develop new vaccines using recombinant technology. Neither of these vaccines has been approved for use in the USA, and they are not widely used elsewhere.

As mRNA vaccines become more widely used, a group of researchers have already started to develop an mRNA vaccine for Y. pestis, so watch this space as development could happen quickly.

Living with the Plague

The bottom line is that plague is not currently a massive threat. About 1000 to 2000 people get it every year-globally, around 7 of which will be Americans. It can be treated with antibiotics if you make it to a doctor early enough. So, while it is scary to think that the plague still exists, you can rest assured there is little danger to you or your family.