What Is Cholera?
Cholera is an infectious disease caused by a bacterium called Vibrio cholerae. The bacteria typically live in waters that are somewhat salty and warm, such as estuaries and waters along coastal areas. People contract V. cholerae after drinking liquids or eating foods contaminated with the bacteria, such as raw or undercooked shellfish.
There are hundreds of strains or “serogroups” of the cholera bacteria: V. cholerae serogroups O1 and O139 are the only two strains of the bacteria known to cause outbreaks and epidemics.
These strains produce the cholera toxin that cause cells lining the intestines to release increased amounts of water, leading to diarrhea and rapid loss of fluids and electrolytes (salts). A single diarrhea episode can cause a one-million-fold increase of bacterial numbers in the environment, according to the National Institute of Allergy and Infectious Diseases.
About 80 percent of people who contract the bacteria don’t develop cholera symptoms and the infection resolves on its own. And of the people who do develop cholera, 20 percent come down with severe symptoms, which includes severe diarrhea, vomiting, and leg cramps. These symptoms can cause dehydration, septic shock and even death within a matter of just a few hours.
People who contract non-01 or non-1039 V. cholerae can also acquire a diarrheal disease, but it is less severe than actual cholera.
Today, cholera is treated through fluid replacement and antibiotics. Cholera vaccines are available, though they only offer roughly 65% immunity, according to WHO.
Origins of Cholera
It’s unclear when, exactly, cholera first affected people.
Early texts from India (by Sushruta Samhita in the 5th century B.C.) and Greece (Hippocrates in the 4th century B.C. and Aretaeus of Cappadocia in the 1st century A.D.) describe isolated cases of cholera-like illnesses.
One of the first detailed accounts of a cholera epidemic comes from Gaspar Correa—Portuguese historian and author of Legendary India—who described an outbreak in the spring of 1543 of a disease in the Ganges Delta, which is located in the south Asia area of Bangladesh and India. The local people called the disease “moryxy,” and it reportedly killed victims within 8 hours of developing symptoms and had a fatality rate so high that locals struggled to bury all the dead.
Numerous reports of cholera manifestations along the West coast of India by Portuguese, Dutch, French and British observers followed throughout the next few centuries.
The First Cholera Pandemic
The first cholera pandemic emerged out of the Ganges Delta with an outbreak in Jessore, India, in 1817, stemming from contaminated rice. The disease quickly spread throughout most of India, modern-day Myanmar, and modern-day Sri Lanka by traveling along trade routes established by Europeans.
By 1820, cholera had spread to Thailand, Indonesia (killing 100,000 people on the island of Java alone) and the Philippines. From Thailand and Indonesia, the disease made its way to China in 1820 and Japan in 1822 by way of infected people on ships.
It also spread beyond Asia. In 1821, British troops traveling from India to Oman brought cholera to the Persian Gulf. The disease eventually made its way to European territory, reaching modern-day Turkey, Syria and Southern Russia.
The pandemic died out 6 years after it began, likely thanks to a severe winter in 1823–1824, which may have killed the bacteria living in water supplies.
Cholera Infects Europe and the Americas
The second cholera pandemic began around 1829.
Like the one that came before it, the second pandemic is thought to have originated in India and spread along trade and military routes to Eastern and Central Asia and the Middle East.
By autumn of 1830, cholera had made it to Moscow. The spread of the disease temporarily slowed during the winter, but picked up again in spring of 1831, reaching Finland and Poland. It then passed into Hungary and Germany.
The disease subsequently spread throughout Europe, including reaching Great Britain for the first time via the port of Sunderland in late 1831 and London in spring of 1832. Britain enacted several actions to help curb the spread of the disease, including implementing quarantines and establishing local boards of health.
But the public became gripped with widespread fear of the disease and distrust of authority figures, most of all doctors. Unbalanced press reporting led people to think that more victims died in the hospital than their homes, and the public began to believe that victims taken to hospitals were killed by doctors for anatomical dissection, an outcome they referred to as “Burking.” This fear resulted in several “cholera riots” in Liverpool.
In 1832, cholera had also made it to the Americas. In June of that year, Quebec saw 1,000 deaths from the disease, which quickly spread along the St. Lawrence River and its tributaries.
Around the same time, cholera imported into the United States, appearing in New York and Philadelphia. Over the next couple of years, it would spread across the country. It reached Latin America, including Mexico and Cuba, in 1833.
The pandemic would die out and reemerge throughout numerous countries for nearly two decades until it subsided around 1851.
Between 1852 and 1923, the world would see four more cholera pandemics.
The third pandemic, stretching 1852–1859, was the deadliest. It devastated Asia, Europe, North America and Africa, killing 23,000 people in Great Britain alone in 1854, the worst single year of cholera.
In that year, British physician John Snow, who’s considered one of the fathers of modern epidemiology, carefully mapped cholera cases in the Soho area of London, allowing him to identify the source of the disease in the area: Contaminated water from a public well pump.
He convinced officials to remove the pump handle, immediately dropping the cholera cases in the area.
The fourth and fifth cholera pandemics—occurring 1863–1875 and 1881–1896, respectively—were overall less severe than previous pandemics, but had their fair share of deadly outbreaks. Between 1872 and 1873, for example, Hungary suffered 190,000 deaths from cholera. And Hamburg lost nearly 1.5 percent of its population due to cholera in the 1892 outbreak.
In 1883, German microbiologist Robert Koch, the founder of modern bacteriology, studied cholera in Egypt and Calcutta. He developed a technique allowing him to grow and describe V. cholerae, and then show that the presence of the bacterium in intestines causes cholera.
However, Italian microbiologist Filippo Pacini had actually identified the cholera bacterium—naming it cholerigenic vibrios—in 1854, though this fact wasn’t widely known (and was likely unbeknownst to Koch).
During the fifth pandemic, Great Britain and the United States were mostly safe thanks to improved water supplies and quarantine measures.
The sixth cholera pandemic (1899–1923) largely didn’t affect western Europe and North America due to advances in public health and sanitation. But the disease still ravaged India, Russia, the Middle East and northern Africa. By 1923, cholera cases had dissipated throughout much of the world, except India—it killed more than half a million people in India in both 1918 and 1919.
Unlike previous pandemics, which all originated in India, the seventh and current cholera pandemic began in Indonesia in 1961. It spread across Asia and the Middle East, reaching Africa in 1971. In 1990, more than 90 percent of all cholera cases reported to WHO were from the African continent.
In 1991, cholera appeared in Peru, returning to South America after being absent for 100 years. It killed 3,000 people in Peru in this first year and subsequently spread to Ecuador, Colombia, Brazil and Chile, and then Central America and Mexico.
Though the current cholera pandemic has affected some 120 countries, it’s largely a disease of impoverished, less-developed nations.
In recent years, there have been a number of devastating outbreaks, including the Zimbabwe outbreak of 2008–2009 that affected some 97,000 people (killing 4,200) and the Haiti outbreak of 2010–2011, which followed the Haiti earthquake and would affect more than 500,000 people.
In 2017, outbreaks of cholera broke out in Somalia and Yemen. By August 2017, the Yemen outbreak affected 500,000 people and killed 2,000 people, making it the largest cholera epidemic in the world today, according to WHO.
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