Why does cholera kill so rapidly

Though cholera has been around for many centuries, the disease came to prominence in the 19th century, when a lethal outbreak occurred in India. There have since been numerous outbreaks and seven global pandemics of cholera. Each year, cholera infects 1. 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. 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.

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 or non V. Today, cholera is treated through fluid replacement and antibiotics. Early texts from India by Sushruta Samhita in the 5th century B.

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 of a disease in the Ganges Delta, which is located in the south Asia area of Bangladesh and India.

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 emerged out of the Ganges Delta with an outbreak in Jessore, India, in , 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 , cholera had spread to Thailand, Indonesia killing , people on the island of Java alone and the Philippines. From Thailand and Indonesia, the disease made its way to China in and Japan in by way of infected people on ships.

It also spread beyond Asia. 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 —, which may have killed the bacteria living in water supplies. 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 , cholera had made it to Moscow. The spread of the disease temporarily slowed during the winter, but picked up again in spring of , 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 and London in spring of 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. In , cholera had also made it to the Americas. In June of that year, Quebec saw 1, deaths from the disease, which quickly spread along the St.

Lawrence River and its tributaries. Researchers have estimated that there are up to four million cases of cholera every year and up to , deaths worldwide, so evidently it is still very much a global health issue.

Over the next 20 years cholera caused a series of serious epidemics, killing tens of thousands of people in England alone. Back then very little was known about how infectious diseases spread or even what infectious diseases were. However, the investigations of John Snow were about to challenge these ideas. A magazine illustration from showing the unsanitary and crowded conditions of London slums. Image credit: Wellcome Library via Wellcome Images. He was particularly fascinated with how infectious diseases, like cholera, were spread.

Since beginning his medical training, he was always keen to investigate water as a vehicle for transmitting infectious disease. In addition to this, water from the Thames was commonly bottled and delivered to pubs and other businesses for consumption! John Snow recognised this and suspected that sewage could be contaminating the water supply and spreading cholera, and probably many other diseases, around the city. In September a particularly severe outbreak of cholera hit the Soho area of London, close to where John lived.

He took the opportunity to find the source of the outbreak, once and for all. He worked around the clock to track the infection by examining hospital and public records. John constructed a map below showing the location of various water pumps around the city and where deaths from cholera were clustered. He showed the number of deaths at each address as a series of horizontal lines, stacked up like a pile of bodies in the street.

At that time the pump not only provided water to many households in the surrounding streets, but also supplied a number of businesses in the area. Some groups of people in the area had managed to avoid cholera despite living and working near the pump so John investigated why this was.

He found one group of men working in a brewery on Broad Street who had remained healthy by avoiding drinking water from the pump and instead sticking to their own beer. Although unbeknown to them at the time, the fermentation process kills the cholera bacteria so drinking beer and gin was actually much safer than drinking water back then! John Snow's cholera map focused on the broad street water pump. On 7th September John took his findings to the town officials and convinced them to take the handle off the Broad Street water pump.

Although they initially refused his request, after removing the handle the outbreak of cholera almost immediately dissipated. The German physician Robert Koch identified the cause of cholera, the bacterium Vibrio cholerae.

A few decades later, the German physician Robert Koch identified the cause of cholera, the bacterium Vibrio cholerae. John is now widely credited with establishing the field of epidemiology. To mark the importance of his discovery, the Broad Street pump is on permanent display in the London School of Hygiene and Tropical Medicine. Many people think that the cholera story ends there, but it is a still very much a major public health issue. Today, cholera causes millions of cases of diarrhoea and hundreds of thousands of deaths every year.

Even in the UK there are about 12 cases of cholera reported every year, although these are generally associated with overseas travel to developing countries. Since the s, developed countries like the UK have built up a solid infrastructure for the distribution of clean water, as well as the disposal and treatment of sewage.

This has prevented the transmission of water borne diseases such as cholera. But there are still many resource-poor areas of the world where sanitation remains a major problem. Cholera is still relatively common in areas of the world where there are no clean water and sewage disposal systems such as in parts of Africa, Asia and South America. However, outbreaks of cholera can still occur in other parts of the world. For example, there was an outbreak of cholera in Haiti in This was after a devastating earthquake that struck the island of Hispaniola, which is made up of the Dominican Republic in the east and Haiti in the west.

The earthquake killed more than , people and caused a loss of infrastructure to Haiti that led to political and social unrest. Symptoms can range from mild to very severe diarrhoea, sometimes with vomiting. In severe cases, diarrhoea is copious - like rice-water - and very frequent and can cause dehydration, shock and death within a few hours — if left untreated. It takes between 12 hours and 5 days for a person to show symptoms after consuming contaminated food or water.

Does everyone infected with cholera show symptoms? Among people who develop symptoms, the majority have mild or moderate symptoms, while a minority develop acute watery diarrhoea with severe dehydration. This can lead to death if left untreated.

Who is most susceptible? Anyone can be infected with cholera - through drinking water or eating food contaminated with the cholera bacteria germs from the faeces or vomit of infected people.

People with low immunity — such as malnourished children or people living with HIV — are at a greater risk of death if infected. Why does cholera cause such rapid de-hydration? Severe symptoms of cholera cause a rapid loss of body fluids through — copious and frequent diarrhoea with or without vomiting.