The Blue Death: Here's How the Horrific Blight of Cholera Got Its Name

It's threatened humanity seven times.
Jaime Trosper

Long before COVID-19 became one of the most disruptive pandemics in modern history, there was cholera. It sounds like one of those old-timey diseases, and it virtually is -- at least for those of us lucky enough to live in countries with adequate water filtration systems. Back in the 1800s, cholera was extremely common worldwide and was (and still is) very deadly. So deadly, in fact, a seemingly healthy person who contracted it could be dead within hours of the first symptoms appearing. Sounds scary, right? Well, the unraveling of the causes of cholera and how it spreads not only saved countless lives but demonstrated for the first time how the science of epidemiology can be used to save lives. 

So, what is cholera? How is it caused? What does it do to the human body? Are there any effective treatments for it? Read on to learn everything you need to know.

What is Cholera?

At its core, cholera is a bacterial infection of the intestine. In severe cases (about 1 in 10), it effectively causes diarrhea so severe, the body loses fluid so quickly, it can't replenish them fast enough, that dehydration, shock, and organ failure soon follow. The culprit, a bacterium called Vibrio Cholerae, is toxigenic and most often can be found in brackish waters and in contaminated water and food. It can sometimes be destroyed using common cleaning products, like chlorine and bleach, but it wouldn't have become so deadly if certain strains didn't evolve to become resistant to destruction.

How does one get cholera? It's pretty simple. All it takes is consuming a tiny bit of food and/or water that harbors Vibrio Cholera, or has been contaminated with the feces of an infected person. Other means of transmission include eating raw seafood or shellfish. 

According to the World Health Organization (WHO), "There are many serogroups of V. cholerae, but only two – O1 and O139 – cause outbreaks. V. cholerae O1 has caused all recent outbreaks. V. cholerae O139 – first identified in Bangladesh in 1992 – caused outbreaks in the past, but recently has only been identified in sporadic cases. It has never been identified outside Asia. There is no difference in the illness caused by the two serogroups."

The National Institute of Allergy and Infectious Diseases further notes, "Vibrio cholerae is unusual in that it competes in the natural environmental community of bacteria in estuarine and brackish waters worldwide. V. cholerae bacteria can increase their numbers in the environment by successfully infecting humans. For a person to be infected by cholera, the bacteria’s genetic material must be present in the intestine. One person infected with cholera can shed into the environment a one-million fold increase in V. cholerae numbers through a single episode of diarrhea." 

It's often possible for the body to naturally fight off the bacterium, largely thanks to stomach acids that can neutralize the threat it poses, but once it enters the intestines, the clock begins ticking. Either you get immediate treatment, or you're in for an extremely bad time. Of course, not all infections are a death sentence. In fact, many of the inflicted might not experience any symptoms at all, others will get away with just stomach flu-like symptoms. Around 1 in ten people will experience extreme side effects, up to and including death. It has been estimated that each year there are between 1.3 to 4.0 million cases of cholera, and 21,000 to 143,000 deaths worldwide from the disease.

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For the unlucky, once the bacteria is introduced into the digestive tract, a  protein called CTX (or choleragen toxin) is generated. The protein begins to bind to the intestinal walls, which triggers a chain reaction in the body, whereby it generates more fluids to compensate. As the body begins to lose said fluids through diarrhea and vomiting, the body eventually reaches the point of hypovolemic shock, where fluid loss means the heart is unable to pump enough blood through the body.

Once the disease has reached this stage, the blood circulating through the body begins to thicken, given there are not enough fluids left to thin it out. If it reaches a certain thickness, blood can no longer travel effectively through the veins, delivering vital oxygen and nutrients to organs.

Other symptoms, which can begin to appear anywhere from 48 hours to five days after exposure, include:

  • Abdominal pain
  • Dehydration
  • Dry mucosa
  • Oliguria (lack of urine output)
  • Nausea
  • Muscle cramps (especially in the legs)

The Blue Death? How does it actually kill?

Some of the nastiest diseases known to man have been given nicknames associated with colors -- like the black death, otherwise known as the bubonic plague. Cholera is sometimes called the Blue Death, because the extreme loss of fluids can turn the afflicted person's skin a shade of light blue. The blue death isn't this disease's only nickname,  of course. The French sometimes call it the "Dog’ death". Other names over the ages have included the Blue Terror and the Black Choler. 

Why does it turn skin blue? It's a little complicated. You see, on average, an adult has around 42 liters of water located throughout the body at any given time. Water is very, very important to a great many biological functions, all the way down to a cellular level. It helps digest food, regulates temperature and other functions, expels waste, protects tissues, is an important component of fluids, helps the brain work, and has many other special functions.

When someone has cholera, they can lose up to 20 liters of water within a very short space of time, which will translate to many internal and external changes. The eyes sink, the skin starts to lose some of its elasticity, and the teeth protrude. Eventually, the body becomes so dehydrated, it enters into respiratory failure, which is when the skin takes on a blue tinge. This is generally followed shortly after death.

Destruction of human lives through history: mapping the cholera pandemics

An endemic disease is one that affects a particular region or population and is largely contained within that boundary. A pandemic is a disease that has worldwide effects, like the Spanish Flu and of course, Covid-19.

Cholera, for its part, has seen both endemic and pandemic outbreaks, and it has killed tens of millions of people all across history. It's origin is not known, as it is impossible to say decisively whether or not outbreaks of cholera-like diseases much earlier in recorded history were definitely caused by cholera. There are many accounts of similar-sounding diseases, dating all the way back to the 4th and 5th century B.C, that very much sounds like cholera outbreaks, but it's impossible to say definitively given the cause of cholera wouldn't be pinpointed for some time to come. Here's a look at seven main outbreaks occurring mostly within the last 200 years:

The first Cholera pandemic: The very first confirmed modern Cholera pandemic began in the Ganges Delta part of India/Bangladesh in 1817. It spread to what is now Myanmar and Sri Lanka, before reaching Japan and China from 1820 to 1822. The pandemic was over by 1824, but by then, the list of affected places included Oman, the Persian Gulf, modern-day Turkey, and other European Territories that were located along trade routes.

It's believed that the source of the first outbreak was due to contaminated rice. It may have died out due to a particularly frigid winter between 1823 and 1824, but not before claiming the lives of an estimated one to two million people. 

The second Cholera pandemic: The second known modern cholera pandemic -- and the first to reach the Americas and Europe -- began in around 1829.  Once again, it's believed to have originated in India and spread along shipping routes. It ultimately caused huge numbers of deaths in a number of countries, including Russia, Germany, Hungary, Egypt, England, France, Canada, the United States, Mexico, and Cuba.

While it is unknown precisely what caused this outbreak, it came to an end in around 1837, but it most certainly would not stay gone for long.

The third Cholera pandemic: The third cholera pandemic is commonly lauded as the deadliest of all time. Beginning in  1852 in India once again (this is likely because there was a reservoir of infection in this country that had not been fully stamped out), it wreaked havoc across Asia, Europe, Africa, and North America. Perhaps the worst single year of the pandemic was 1854 when 23,000 people died in England alone. Russia was perhaps the hardest hit, with an estimated 1 million people perishing.

Fortunately, I guess you could say, the pandemic would eventually make its way to the Soho area of London, where physician John Snow, who is often regarded as a father of modern epidemiology, would trace the source of the outbreak to a public water pump on Broad Street. Although germ theory hadn't yet found its footing, Snow spoke to local residents and was able to map the pattern of the infection and death, showing that cases were much higher around this particular water source.

His studies of the pattern of the disease were convincing enough to persuade the local council to disable the pump. This significantly reduced the cases in the area. It was later discovered that the water for the pump was polluted by sewage contaminated with cholera from a nearby cesspit.

The fourth Cholera pandemic: Once again, the origin of the fourth outbreak, which lasted between 1863 and 1875, was traced back to the Ganges Delta region of India. This time the disease traveled to Mecca along with Muslim pilgrims, from which point it spread through portions of the Middle East, Russia, Africa, North America, and Europe. 

In the first year alone, it claimed the lives of an estimated 30,000 to 90,000 pilgrims; around 90,000 Russians in 1866, 70,000 people in Zanzibar between 1869 and 1870; along with 165,000 people living in the Austrian Empire (30,000 in both Hungary and Belgium, and around 20,000 in the Netherlands). The carnage didn't end there. Roughly 113,000 people died in Italy; 80,000 Algerians lost their lives in the same year; along with 50,000 Americans mostly in the New Orleans area. 

The fifth Cholera pandemic: The fifth cholera pandemic - beginning in 1881 and lasting through 1896 - affected parts of Europe, the Americas, Russia, Spain, Japan, Persia, but it was to become one of the last outbreaks to heavily affect so many different countries or claim nearly so many lives. 

Approximately 90,000 people perished in Japan in a two-year period beginning in 1887; 8,600 died in 1892 in Hamburg, Germany (the largest source of death in Europe); and roughly 200,000 died between 1893 and 94 in Russia. Believe it or not, the fifth cholera outbreak is one of the more minor ones in history, despite lasting 15 years.

The sixth Cholera pandemic: The sixth pandemic, which started in 1899 and didn't end until 1923, did the least damage to populations across western Europe, but it still made its way to places like Russia, the Philippines, Mecca, and India. India, which was once again the origin of the outbreak, was hit especially hard, as were Italy, Greece, Turkey, and the Balkans. More than 34,000 people died in Egypt over a three-month period, and some 4,000 Muslim pilgrims were estimated to have died in Mecca in 1902. Russia was also severely affected, with more than 500,000 people dying by 1923.

This one didn't make its way to the Americas, but it did claim an estimated 800,000 lives in India. However, after 1923, cholera receded from most of the world.

The seventh Cholera pandemic: Unlike the previous six cholera pandemics, the seventh started around the island of Celebes in Indonesia in 1961, and spread to Bangladesh, India, North Africa, Italy, and USSR, reaching Africa in 1971 and causing immense amounts of carnage -- all the way into the early '90s.

According to history, Africa "was the origin of more than 90 percent of all cholera cases reported to the World Health Organization (WHO). In 1991, 19 African nations reported nearly 140,000 cases in total. A particularly large outbreak occurred in 1994 among the many hundreds of thousands who fled widespread killing in Rwanda and occupied refugee camps near the city of Goma, Zaire (now the Democratic Republic of the Congo). Tens of thousands perished from cholera during the first four weeks following their flight."

We haven’t seen a true cholera pandemic in more than three decades, largely thanks to improved water filtration systems and sanitation guidelines, as well as effective treatments. That said, cholera outbreaks are still regularly seen in developing countries and in areas hit by natural disasters. In 2017, more than 500,000 people were infected with cholera in Yemen, with some 2,000 people losing their lives

Fortunately, even severe cholera is no longer an automatic death sentence. Relatively simple treatments, such as the use of oral rehydration solutions (a cheap, pre-packaged mixture of sugar and salts that is mixed with 1 liter of water and drunk in large amounts) allow sufferers to replenish lost fluids before their internal organs begin to shut down due to severe dehydration. With prompt rehydration, fewer than 1% of cholera patients die.

According to the CDC, "Oral or intravenous hydration is the primary treatment for cholera. In conjunction with hydration, treatment with antibiotics is recommended for severely ill patients. It is also recommended for patients who have severe or some dehydration and continue to pass a large volume of stool during rehydration treatment."

As with any disease, prevention is superior to treatment. Make sure you only drink water from clean sources, always wash your hands thoroughly and never eat raw or undercooked fish. With these simple steps, the blue death won't be nipping at your heels. 

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