spreading around sickening and killing millions. But what you probably didn't know is that

the disease has created one of the world's longest pandemics ... ever. So what exactly

does cholera do to the body? How can we prevent it? And why has this ancient disease lasted

throughout the ages?

It's actually a good time to be talking about cholera because of the COVID pandemic right

now because cholera causes pandemics and we've had seven pandemics of cholera in the last

200 years.

I am Anita Zaidi and I'm the director for the Bill and Melinda Gates Foundation

in enteric and diarrheal diseases.

First discovered in the Ganges delta in India, Cholera is caused by the bacteria vibrio cholerae.

And it's been around since ancient times, with multiple pandemics starting in 1817.

During that first outbreak was when the world really got to know about this disease. Out

of the more than 200 serogroups of V. cholerae, only two are known to actually cause Cholera:

O1 which is responsible for most of the recent outbreaks, and O139 which is linked to more isolated

cases.  So how exactly does the bacteria spread?

Well, that mystery was solved thanks to a pump back in 1854.

John Snow is like one of those legendary epidemiology figures that everybody learns about when they

learn about cholera. John Snow noticed, that there was a lot of cholera happening in London

and he started looking at the patterns of how cholera was spreading and he noticed that

the areas which had high incidence of cholera, all had a similar drinking source, a water pump.

And so he removed that water pump and it showed that cholera rates in those areas went down

and it's a famous epidemiology story about one smart person paying attention to patterns

of disease and figuring out how to stop it. And two centuries later, we're still trying

to figure it out.

What we know is that when a person contracts cholera, it's usually through a contaminated

source like drinking water that's come into contact with infected feces. Now, after that

first sip, it takes the bacteria anywhere from a few hours to a couple of days to begin

wreaking havoc on the body.

When you ingest the bacteria, it goes from your mouth, into your esophagus, into your stomach, and then

pass the stomach and where it causes disease is in the small intestine.

Once there, the bacteria swims towards the intestinal wall, pushing through the thick

mucous layer of the intestines' epithelial cells where it then attaches itself and begins

to multiply, releasing toxins that stimulate the cells to secrete water. And that's where

the chaos begins.

What it does to the body is it will cause vomiting. It causes stomach pains. It causes

bad watery diarrhea. All of a sudden, all of the water in your body starts being secreted

through your intestinal cells. The secretion of fluids is so massive that you basically

pour out liters of fluid from your body. That's how cholera kills, right, because it just

dehydrates then all of the organs shut down. Like if you've seen a cholera dehydration in

your life once, you never forget it.

Oh and if that weren't scary enough, that rapid loss of fluid can all happen within

a matter of hours of showing symptoms.  Thankfully, only a minority of cases experience

this. While the rest have mild to moderate symptoms, developing bouts of nausea, vomiting,

and loose stools. But milder cases still present a threat because patients can excrete V. cholerae

for up to two weeks after the infection has passed.

Luckily though, we know how to treat it. For patients suffering, the most important thing

to do is to replace the rapid loss of minerals, so a solution of oral rehydration salts is

usually given and in the more extreme cases, IV fluids can be used to get the job done

faster. And to stem future spread, antibiotics can help reduce the amount of the bacteria

present in the stool.

As for prevention, there are two main methods: One is of course making sure that people have

access to clean water and sanitation and now we know much more about the types of areas

where cholera spreads, they're called hotspots, where there is a lot of people living in close

proximity, so high population density slums, inner city areas in developing countries and

typically they are close to a body of water.

While the other is vaccines. Currently, there's the oral cholera vaccine, which is taken in

two doses one to two weeks apart. It's the main one used in mass vaccination efforts

and it's produced by two manufacturers: Euvichol and Shanchol. And the best part is,

is that it's really cheap, at less than two dollars a dose.

This vaccine has now saved thousands and thousands of lives. 30 to 40 million doses are being

used every year in the cholera hotspots.  This is for the first time that so many doses

of vaccines are being used that we are now seeing a number of deaths from cholera decreasing

in the world for the last two years and so that's really good news on cholera.

So if we know how to treat the disease and have a way to prevent it, then why is this

ancient disease still an issue today?

The reason that Cholera has persisted is that we have not addressed poverty to the level

that we should and with time we know how Cholera happens and where it happens and we should

be able to focus on those cholera hotspots as first priority for areas which need improved

sanitation and hygiene. And that's countries working together prioritizing health over

other things and improving their own infrastructure.

So when we can do that, cholera will disappear.

To help get there, the World Health Assembly,

which is the WHO's decision making body, pledged to eradicate cholera by 2030, hoping

to reduce deaths worldwide by 90%. And if we can achieve that goal, we may soon see the

end of one of the world's longest pandemics.

We have an opportunity to get rid of cholera from the world forever and also an opportunity

for the world to understand how we have worked together as a multinational effort, coming

together to control cholera as an infectious disease pandemic and what are the lessons

learned for controlling COVID in the same way.