I'm professor Hans Rosling.

I'm going to show you

why it is that the Ebola epidemic

is so dangerous.

It's because one patient, on average,

keeps infecting two other persons.

That doesn't sound so dangerous,

but I will show you

what it means in reality.

If this is the first person
infected in the country,

that person will infect two others,

and this one will infect two others,

and this also.

Each of this ones infects two others.

That doesn't look too bad,

but look what happens
when it continues.

There, it's already
32 persons infected.

If we let this continue,

the epidemic will become dangerous
for the whole world.

Let me show you the danger
in another way.

Look at the blocks.

Some diseases increase like this,

from month to month:

1, 2, 3, 4, 5, 6, 7.

That's not how Ebola increases.

If one patient infects two others,

it doubles from month to month,

so this is what it happens with Ebola:

1, 2, 4, 8, 16, 32.

And the next month,
twice as many: 64!

So you see,

if actions are taken this month,

this is how much resources are needed.

If you delay the actions
for another two months,

you'll need
four times as much resources.

Not to mention
if you delay it further.

There is no alternative:

the Ebola epidemic has to be stopped now.