What is Plague | what is Black death | what is Bubonic plague

The Plague

The Plague, also known as the Black Death, is beyond infamous.

It is one of the deadliest, most devastating diseases mankind has ever seen.Not only has the Plague killed an incredible number of people since it first broke out, but it has also had a significant impact on art, economics, and pop culture over the centuries. It was even recorded in the Old Testament, so it is literally biblical.

The Plague is an acute infectious disease with high mortality rate, meaning that it kills many of the people it infects. It has caused three major world pandemics. Each time, this disease killed incredibly large numbers of people, and according to some historians, irreversibly changed the Fabric of society.

The Justinian Plague:

This is the  first major pandemic in the year 541 AD, spread from central Africa to Egypt and the Mediterranean, killing an estimated 5,000 to 10,000 people per day at its peak, and nearly 50 million people overall, or almost a quarter of everyone alive.

The Black Death:

The Black Death or ‘Bubonic Plague’ killed one-third of the population of Europe in the mid-1300s. Imagine the horror of 1347, when 12 ships from the Black Sea arrived in Italy, with everyone onboard unexpectedly either dead or very close to dead. Things got worse from there, and five years later, the Plague had spread, killing over 25 million people across Europe, and another 25 million in Asia and Africa. 

Where did it come from?

While it's difficult to trace with any real certainty, the outbreak is believed to have originated in the Gobi Desert in Mongolia early in the fourteenth century. Prior to this, the disease had existed for centuries in regions of Asia, with small outbreaks occurring from time to time. Any one of these could have been the source.

The Late 1800s Death:

The third pandemic began in the late 1800s and didn’t end until 1959, killing over 15 million people across China, Hong Kong, India, Australia, and the Americas. So we are talking about huge percentages of the global population being wiped out by this disease, making it no surprise that we refer to it as the Plague.

You might think that this horrific disease must be extinct by now, but the Plague is still alive and well, causing outbreaks across the world even today. 

The difference is that we know so much more about it now, and it can be cured if treated quickly.

The most common forms of Plague are:

1.    Bubonic Plague
2.   Septicemic Plague
3.    Pneumonic Plague

All of which are very serious.

Symptoms of Bubonic Plague are:

Patients experience very sudden onset of:

• Fever
• Aching limbs
• Chills
• Headache
• Groin would start to swell and turn black.
• And one or more painfully swollen lymph nodes, called “buboes.”

These relatively large buboes form in the neck, arms, or very commonly in the groin, with potential to spread to the rest of the body.

'Buboes', gave the bubonic plague its name.

These black swellings are where the 'Black Death' gets its name.

Symptoms of Septicemic Plague are:

With Septicemic Plague, the bacteria have moved into the blood.

Patients with septicemic plague experience:

• Bleeding from their mouth, nose, or bottom
• Bleeding under the skin, blackened and/or dying skin
• Vomiting
• Diarrhea
• Stomach pain
• Shock

Symptoms of Pneumonic Plague are:

Finally, Pneumonic Plague is the rarest form, in which the bacteria spread to the lungs.

A patient might experience:

• Shortness of breath
• Pneumonia
• Bleeding
• Bloody cough.

Of the three types, pneumonic plague is the most serious, and is the only type that can

Spread in the air from person-to-person.

So what in the world causes this Plague, exactly?

The causative agent of Plague, Yersinia pestis, wasn’t discovered until the 1894 pandemic By French bacteriologist Alexandre Yersin.

Also this bacterium is gram-negative, it can grow in the presence or absence of oxygen, and it’s a member of the Enterobacteriaceae family.

A common characteristic of Yersinia species is their ability to survive in phagocytes,

Which are a type of immune cell that typically engulf and destroy bacteria.

Instead of getting sucked into a phagocyte and killed, these bacteria secrete proteins that are able to disarm the phagocyte. They essentially take over the immune system from here, triggering cell death called apoptosis in immune cells called macrophages, and suppressing other immune processes that would otherwise signal distress to the body, such as cytokine production.

Many species of Yersinia carry plasmids encoding additional virulence genes as well, which allow them to double down on their deadly cell takeover.

All Yersinia infections are zoonotic, meaning that they’re passed from an animal or insect to a human. Humans are simple accidental hosts.

In the case of Yersinia pestis, there are two forms of infection.

Rats are the natural reservoir, meaning the habitat where the bacteria normally live, for urban plague. Instead, squirrels, field rats, domestic cats, and rabbits are the natural reservoir for sylvatic plague.

The way it works is this: the bacteria maintain their existence in a cycle involving rodents and fleas. Fleas become infected during a blood meal from an infected rat. The bacteria then replicate in the gut of the flea, and the flea can transmit the disease to another creature when it goes in for another blood meal.

In general, the plague bacteria can be transmitted to humans through bites from an infected flea, contact with contaminated tissue or fluid such as a hunter skinning an infected animal without protective gear, or infectious droplets from an infected person’s coughs.

Transmission by infectious droplet hasn’t been documented in the U.S. since 1924, but happens fairly commonly in developing countries. Once infected, it typically takes 7 days or less after a flea bite for a person to start showing symptoms of bubonic plague.

In the cause of pneumonic plague, the incubation period is typically just two or three days. These patients are highly infectious and face a mortality rate of above 90% if left untreated.

The good news is that although the plague is still serious, it’s absolutely treatable with antibiotics. The earlier a patient seeks medical care, the better their chances for a full recovery.

The Plague is a prime example of how important science is to our civilization.