Cholera was called the 'Blue Death'

John Snow—not the one from 'Game of Thrones'—determined that contaminated water sickened London

His pioneering epidemiology work during an 1854 cholera outbreak mapped out the commonalities between people in London who were getting sick. He discovered that ill people were getting water from the same Broad Street pump. Before Snow's work, the prevailing theory was that bad air sickened individuals instead of cholera-causing bacteria in the water.

In 1892, two scientists purposefully infected themselves with cholera bacteria

When they became ill—one with mild diarrhea and the other with severe cholera—researchers pointed to that as proof that the pathogen caused the disease.

The cholera bacteria was first isolated in 1854—but the discovery was largely ignored

The pathogen was isolated by the Italian physician Filippo Pacini in Florence, Italy, though his discovery was largely ignored in favor of the popular miasma—bad air—theory of disease at the time. The pathogen was separately isolated about three decades later by German microbiologist Robert Koch.

Cholera went global thanks to global trade

The first cholera pandemic grew from an outbreak in India, in 1817. Scientists suggest it spread from there throughout the continent and onward to Africa, Russia and Europe through the poop of traders.

More than 4,000 people died from cholera in 2023

This global health threat sickened more than half a million people in 2023 and killed 4,007 people. That's a 71% increase in deaths as compared to a year earlier. (Report only offered in PDF format.)

Play 17th-century death roulette

Before modern science and medicine, death was much harder to escape. Using real mortality records from London's Dreadful Visitation–a collection of all the Bills of Mortality from 1665–this interactive game gives you an idea of what may have possibly killed you during the Great Plague. Grow your appreciation for life today as you stumble upon causes of death like “livergrown” and “drowned at St. Katharine’s by the Tower”.

Maryland required cholera researchers to fly a yellow warning flag—signifying quarantine dangers in the 1970s

University of Maryland Hospital researchers intentionally infected volunteers with the cholera bacterium in the late 1970s to further their understanding of the disease. They proceeded with this work following the recommendation of a US government panel. (Some users may encounter a paywall.)

Learn how cholera bacteria sicken humans

Once a person has ingested large amounts of the bacteria, typically through contaminated water, cholera bacteria begin producing and releasing a toxin inside their host. It attacks the mucosal lining of the intestine, making it hard to absorb liquids. This process leads to cholera's characteristic symptoms, like voluminous, watery diarrhea.

The canal carried germs as well as goods

In 1832, North America’s first cholera epidemic spread inland by way of the Erie Canal, carried by immigrants arriving on ships. Fearful towns barred passengers from disembarking, yet cholera, smallpox, and other diseases still traveled the waterway.

The wonderfully named Vibrio diabolicus is a cousin of the cholera-causing bacterium

This bacterium, which belongs to the same genus as the cholera bacterium, was initially isolated from deep-sea hydrothermal fields. It was sampled from water that was scooped up during a French-American cruise in October 1991.

Diphtheria was once a leading childhood killer before antibiotics and vaccines

In 18th- and 19th-century outbreaks, some New England families lost as many as eight children to diphtheria, and fatality rates in hospitals often topped 60%. The invention of antitoxins, penicillin, and vaccines dramatically reduced deaths.

About 20% of people infected with cholera have severe symptoms

That's according to studies from outbreaks in Bangladesh. Most people who contract the disease have mild or moderate symptoms, or none at all. Yet anyone infected with the disease-causing bacteria can shed the pathogens in their feces for a few days, or even up to around 10, seeding the environment with bacteria.

Two-thirds of soldier deaths during the war were due to disease

Roughly two-thirds of all Civil War deaths resulted from disease rather than battle. Poor sanitation, contaminated water, and limited medical knowledge made camps breeding grounds for dysentery, typhoid, and other deadly infections.

We're in the middle of a decadeslong cholera pandemic

In 1961, the world's seventh recorded cholera pandemic started in South Asia, and it has continued through the decades. India and Bangladesh are at particular risk. This pandemic is driven partly by conflict, population displacement, extreme weather, and poor water infrastructure.

Robert Koch won the Nobel for his tuberculosis work, but he also pioneered cholera research

Koch was one of the first scientists to isolate the bacterium that causes cholera while investigating an outbreak in Egypt in 1883. He went on to advise about rules to control cholera outbreaks, which formed the basis of the disease control approaches and water hygiene techniques still used today.

Without the option of modern blood transfusions, some doctors in the mid-1800s tried to help save cholera patients by injecting them with cow's milk, hoping it would boost their nutrition and hydration.

Oral rehydration solution was developed in the 1960s in response to cholera deaths.

The bubonic plague spread in three waves over 600 years

The Black Death refers to the first wave of the plague, which swept through Europe in the 14th century and killed 25 to 50 million people. Caused by the bacterium Yersinia pestis carried by fleas (often on rats), the human toll was roughly one-third of Europe's population at the time.

In the 19th century, ice-cream-related illnesses were somewhat regular in America thanks to vendors' poor hygienic practices.

1 in 4 people around the world don't have access to clean water

Poor water sanitation puts people at risk of acquiring this diarrheal infection. Cholera infections are on the rise due to extreme weather events and conflict. In recent years there have been cholera outbreaks in locations that hadn't seen the disease in many years, including Haiti.

Blood color differs across the animal kingdom, with some animals producing blood that appears green (a group of lizards in New Guinea) or blue (horseshoe crabs).

Paris and Boston were redesigned partly to combat cholera's spread

Georges-Eugène "Baron" Haussmann, who oversaw Paris's redesign in the 1800s, replaced many of the city's narrow streets with wide boulevards. This was done at least in part to bring more air and light into the city to help control cholera. Architect Arthur Gilman redeveloped Boston's Back Bay to similarly combat cholera, among other reasons.

See how cholera spreads in a community

This animated video offers a comprehensive look at how cholera spreads. It makes clear why it's so difficult to stamp out this disease in communities around the world. It also details what steps can help control cholera.

Harmful algal blooms can occur in warm, nutrient-rich, stagnant waters and are often associated with the rapid reproduction of blue-green algae—a misnomer for cyanobacteria, not algae.

When was the first blood transfusion?

In the 1600s, an English doctor transferred the blood from one dog to another via quills. The procedure ended when one of the dogs died. This article details the early days of blood transfusions, which turned toward humans shortly after the 1666 dog experiment and involved putting the blood of a sheep into a human recipient (who reportedly survived the encounter).

The medical profession has a dark history of 'body snatching' for education

This term originally referred to secretly removing corpses from graves for sale—usually to medical schools where they were used for education. The practice dates back at least to the 1300s but still—much more rarely—persists today.

The pharmaceutical industry evolved, in part, from the discovery of synthetic dyes

In 1856, a chemist accidentally discovered mauveine, the world's first synthetic dye, while trying to make quinine to treat malaria. The synthetic dyes that followed helped reveal germs under microscopes, paving the way for modern imaging techniques and breakthrough treatments, such as antibiotics.

Extreme weather conditions heighten cholera risks in settings like refugee camps

Runoff from sewage—exacerbated by situations like flooding or extreme rains—heightens this threat. Increasing temperatures also create the ideal conditions for the bacteria to reproduce, increasing transmission risks.

Hippocratic doctors treated severe mental illness with the poisonous plant hellebore

Since symptoms like hallucinations were believed be due to an imbalance of black bile, yellow bile, blood, and phlegm, the treatment at the time was to bring those humors back into balance. That meant standard treatments could include bleeding a patient or using substances like hellebore to induce vomiting or diarrhea.

Wood that changed the color of water was the earliest recorded example of fluorescence

Lignum nephriticum, a tea used to treat kidney and urinary illnesses, was described in the 16th century as derived from white wood that turned water a bluish hue. However, in the 17th century, accounts described the wood as reddish and creating a kaleidoscope of colors in water. In 1915, the sources were identified as two different woods, which absorb UV radiation and emit visible light.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Pneumonia was once a leading killer before penicillin treatments

In the early 20th century, pneumonia was a top cause of death worldwide, often fatal without effective treatment. Penicillin turned a once deadly infection into one of the most treatable bacterial diseases.

Historically, cholera has repeatedly disrupted the Hajj for Muslims

Outbreaks of the disease throughout the 19th century and the beginning of the 20th, killed thousands of religious pilgrims as they sought to complete this obligatory pilgrimage.

The virus was officially described for the first time in 1789

Michael Underwood, an English physician and surgeon, was the first to describe the disorder, noting it caused disability in the lower extremities in children. Large-scale outbreaks of the disease were not observed until the late 19th century.

'Melancholia' was the ancient Greek term for depression

"Melancholia" in Hippocrates's time was derived from the Greek word for black bile. This term made sense in its context since the Greeks believed that depression stemmed from an improper balance of the four humors.

The strange endurance of consuming blood for health

Blood's importance to humanity is best summarized this way: without it, we die. This importance naturally begets assumptions about its medicinal properties, many of which appear accessible through drinking or eating the fluid connective tissue. This article details the history of blood drinking, from ancient Roman gladiators to modern-day sanguinarians.

The history of germ theory, which explains that illnesses are caused by microorganisms

For centuries, the miasma theory, which held that illnesses were caused by clouds of "bad air" produced by decaying organic matter, was the accepted explanation for the spread of disease. The development of microscopes and the subsequent technology to isolate bacteria and test disease spread in mice greatly contributed to contagionists overturning miasmatists.

Scientists suspect that Alexander the Great and Rudyard Kipling are among the public figures that may have died from food poisoning.

'Dr. Death' (4 Seasons)

Taking a unique angle on the true crime genre, this series explores medical professionals whose lust for fame and success stops at nothing—even others’ lives. Each season explores a different doctor and the systems that enabled them. Begin with the season one and the story of Christopher Duntsch, accused of maiming or killing several patients, including leaving one quadriplegic and another brain-dead.

Cholera can persist in the environment, unlike smallpox, which needs a human host

Vibrio cholerae is the pathogen that causes cholera. It can reproduce in the environment without a human host, which means it's formally called a facultative pathogen. Obligate pathogens need a host to reproduce. Examples of obligate-based diseases include leprosy and smallpox.

Typhoid smells like freshly baked brown bread

Certain ailments are associated with documented scents, including diabetes, Parkinson's disease, and typhoid. The skin of people with yellow fever, for example, can smell like a "butcher shop."

Volcanoes in the 1340s likely helped trigger the Black Death

The "bubonic plague" that wiped out roughly half of Europe and Asia originated from many factors. Recent research suggests volcanic eruptions contributed as well. The "aerosol" effects of matter released from eruptions likely prompted famine and accelerated the spread of infected fleas riding on grains avoiding spoilage.

Cholera vaccines can protect people from disease for months—or even years

There are three recommended cholera vaccines on the market. The number of required shots and the period of protection they provide vary, but each of them can be life-saving.

New evidence suggests the eruption's victims died as their blood boiled

While most Pompeii victims suffocated or were crushed, spectroscopic analysis of bones from a nearby town indicates something more extreme: exposure to superheated gas that instantly boiled blood and caused deadly internal trauma.

What was the London Beer Flood of 1814?

On this day 209 years ago, a 15-foot-high wave of beer roared through the streets of an impoverished London neighborhood, killing eight people. Read this beer historian's account of the tragedy to learn more. The beer had burst from the nearby...

Penicillin ended scarlet fever’s deadly threat to children

Between 1840 and 1883, scarlet fever was among the leading causes of childhood death in the United States, with case fatality rates ranging from 15% to 30%. Today, thanks to antibiotics like penicillin, the mortality rate is below 1%.

Hear how the Black Death reshaped Europe's economy

The Black Death killed tens of millions across Europe, but the labor shortages that followed shifted economic power. With fewer workers available, survivors demanded higher wages and better conditions—sparking what historians call a medieval “Golden Age of Labor.”

A family's yearslong poisoning

Over 14 years, a southern Indian family slowly lost six members, several of whom were found foaming at their mouths. Upon the third death, a post-mortem examination was requested, revealing cyanide had been ingested, though it was ruled as self-inflicted. Several will edits and three deaths later, relatives turned a critical eye toward Joliyamma "Jolly" Joseph, who had married into the family and been present at each death.

Listen to how the 1902 'poison squad' experiments changed food safety in America

As part of government research, a group of young men were paid to eat standard American food—replete with food additives like borax and formaldehyde—which revealed the dangers of unregulated food. The work was led by the first FDA commissioner, Harvey Wiley, who helped end the "century of the great stomachache."

Before 1920, during the Deadball Era, a single baseball was used throughout a Major League game, leading to a notoriously dirty style of play.