But, in the end, we succeeded, and the last case of smallpox this little girl, Rahima Banu Barisal, in Bangladesh when she coughed or breathed, and the last virus of smallpox left her lungs and fell on the dirt and the sun killed that last virus, thus ended a chain of transmission of history's greatest horror.

It wasn't just India that had smallpox deities smallpox deities were prevalent all over the world.

Why not? Every plant virus, every insect virus, every marine virus.

And they caught smallpox in the one remaining place that had smallpox, and they went home to die.

Smallpox early detection, early response.

We declared smallpox eradicated in 1980.

We've seen the eradication of smallpox.

Everybody is immune to smallpox nowadays.

Avelile had the virus, she was born with the virus.

But in that year, smallpox exploded throughout India.

OK, now smallpox is an extremely distressing illness.

Larry Brilliant Smallpox was the worst disease in history.

I wanted to show you the stages of smallpox.

We know the virus will mutate. It will be a different virus.

Virus Killer

And each spot represents a different family of virus or species of virus.

But smallpox eradication was hard it was very, very hard.

The key to eradicating smallpox was early detection, early response.

Day seven, they show the classic scars of smallpox umbilication.

In that year, there were 34 countries affected with smallpox.

So, how we eradicated smallpox was max vaccination wouldn't work.

They are struggling with the goal of wiping out smallpox.

There are other kinds of smallpox that are not like that.

Flat smallpox, which killed 100 percent of people who got it.

I've probably had 50 women die. They all had hemorrhagic smallpox.

And India was the place where smallpox made its last stand.

But smallpox was the fourth disease that was intended for eradication.

We had Dr. Larry Brilliant talking about how we eradicated smallpox.

When you read the biblical plague of boils, that was smallpox.

Pharaoh Ramses the Fifth, whose picture is here, died of smallpox.

The virus is defeated.

And a pig disease, a pig virus, and a human virus can both proliferate, and because of their kind of reproduction, they can combine and produce a new virus.

Virus protection and virus development constitute an uneven arms race. A virus can be just a couple hundred lines of computer code, compared to hundreds of thousands of lines for anti virus programs, which must be designed to detect wide classes of enemies.

This is the polio virus.

These are virus assembled nanowires.

Here we come down with the eradication of smallpox, better education, health service.

I got to see the last case of killer smallpox in the world.

And I'm coloring these small windows blue if another virus shares an identical sequence in its genome to that virus.

And so we use a virus that's a non toxic virus called M13 bacteriophage that's job is to infect bacteria.

But to see smallpox from the perspective of a sovereign is the wrong perspective.

Images of limb regeneration and faces filled with smallpox 21 percent of the conference.

In the Summer of Love, in 1967, two million people, children, died of smallpox.

To eradicate smallpox, we had to gather the largest United Nations army in history.

It could be some virus types.

So, we clone the whole virus.