Few of the monsters that evolution created have
been so successful at hurting us as the variola virus, responsible for smallpox. The carnage
it caused was so terrible and merciless that it compelled humankind, for the first time,
to act truly globally. It was one of the greatest wins of our species over the ancient
powers of nature, all made possible by… cows. Variola is a virus, a tiny machine that only
seeks to reproduce itself. Evidence of It has been found in Egyptian mummies and in writing
from India and China as old as 3000 years. 1300 years ago smallpox killed up to a third of
Japan’s population. By the sixteen hundreds, it was one of the major causes of death worldwide.
In late 18th century Europe, it killed 400,000 a year. Every third person who went blind did so
because of this virus. Even in the 20th century, a hot second ago in history, it still killed at
least 300 million people. Smallpox is an abusive monster that returns over and over and over
again, killing, maiming, and disrupting societies. How could variola be so incredibly deadly for
so long and how could we have forgotten its horror so quickly? In 2023, there are only
two laboratories left where the living virus is officially stored for research:
in Koltsovo, Russia and in Atlanta, USA. Which is certainly a good idea
because what could possibly go wrong? Let’s say that through an unfortunate series of events the virus got out and you got
infected. What would happen to you? How Smallpox Kills Variola is highly infectious and catches a ride
in small droplets you breathe in. Immediately it begins to infect the cells that line your throat
and starts killing them to cause chaos. Why? To trick your body into giving it
a lift. Whenever cells in your body die a violent death, your immune
cells immediately stream to the site of infection to help out. In
this case that backfires horribly. As immune cells begin cleaning up dead
cells, eating viruses and killing infected cells , variola infects a crucial cell of
your immune system: Your Dendritic cells, intelligence cells that gather information
and leave the battlefield to get help. They enter your lymphatic system, a highway
network that spans your entire body and connects hundreds of immune bases. In these
bases your heavy defenses are activated and should be the last place an enemy would want
to invade, but Variola wants to get here. For about 12 days, the virus quietly
infects civilian and immune cells, jumping from cell to cell infecting more and more
of them. At some point a critical threshold is reached and variola starts its attack for real.
Millions of viruses use the lymphatic highway to spill into your blood and organs, infecting
your whole body. Suddenly variola is everywhere. But despite this global attack, your
adaptive immune system is struggling to wake up. Your immune cells look for and use
critical transmitters called interferons to mobilize the body against viruses. Interferons,
as the name suggests, interfere – significantly slowing down virus infections but also quickly
activating millions of anti virus weapons. But Variola is able to deactivate interferons,
which stuns the anti virus side of your defense system. Other systems would usually help
- like the complement system, a sort of mobile minefield that can destroy viruses but
variola also manages to shut this down too. And so, with little resistance variola spreads
everywhere and infects billions of your cells all over your body. Among the infected are your
capillaries, the smallest blood vessels in your body, which die in great numbers. All this death
activates an immune cell that you really don’t need right now but that is attracted by death:
The Neutrophil. Normally an efficient killer of invaders great and small, it is not very effective
against smallpox. And even worse, Neutrophils fight by vomiting deadly chemicals, which
kills even more of your cells. On top of that, they order inflammation, fluids streaming from
your blood vessels into your tissue. All over your body, as first millions, then billions of your
cells die, you get a rash that only gets worse and worse. Pus and cellular junk fills it up as
your body swells up with hundreds of lesions, all over your skin and inside, even on your organs,
all filled with billions of variola viruses. Now the critical phase begins. As you fight
for survival, you burn up in a high fever, thousands of battlegrounds drain your blood of
fluid that streams into your tissue and organs. Blood clotting appears all over your body while
floods of toxins from dead cells build up and can cause organs to fail. Your lungs fill up with
fluid, making it harder and harder to breathe. One of two things happens now: Either your immune
system wrestles back control – heavy weapons have been dispatched, killing infected cells, cleaning
up the thousands of infections one by one, killing variola wherever it can be found so
you can slowly begin to recover. The immune system will forever remember variola, making
you immune forever. Or, you die, overwhelmed by the infection and your immune system's
panicked reaction to the body wide infection. About a third of people who contract
smallpox don’t survive. And if you survive, you are very likely branded by scars and
may even lose your eyesight or hearing. For thousands of years this terrible disease
ravaged the world, leaving death and destruction, traumatized and maimed survivors. Until
one day, humanity said: “enough”.
Why don’t we have smallpox anymore? Smallpox is one of the worst diseases
humanity has ever known. A murderous, family destroying, life ruining monster.
There was nothing you could do for the infected – but people noticed that
if you survived, you were immune. So out of desperation, they came up with a
dangerous practice of variolation: Take scabs from an infected person that had a mild case of
smallpox, let them dry out and grind them to a fine powder. Then blow the powder up the nostril
of a patient or scratch their skin with it. If things went well, they only got a mild version of
smallpox and gained immunity against the disease. Variolation probably worked because it introduced
the variola in a part of the body the virus wasn’t prepared for, disabling most of its nasty
tricks. And because the inoculation was left to dry out, that damaged the virus
so it could not cause the full disease. Unfortunately 2-3% of all patients still died
because they got the smallpox or suffered other diseases as a result of treatment. Still,
smallpox was such a horrible and to some degree, unavoidable disease that people took the
risk, for themselves and their children. Variolation spread around the globe,
while Variola continued to kill millions. A victory over the virus only became a real
possibility when scientists realized that it was not necessary to variolate with the
real smallpox disease, but much safer to use material from cowpox, a variant that affected,
surprise, cows. A truly revolutionary step – and only a few years later, this led to one of
humankind's most outstanding achievements: Vaccinations. The innovation was simple –
instead of using the real virus to train the immune system, use a related virus, cowpox,
that was only mild but also gave you immunity. Still, it would take another 200 years, countless
individuals fighting the monster where they could, delivering vaccines to the most remote places
on earth. All the while the disease ravaged on, killing over 300 million people
in the 20th century alone. In 1966 the World Health Organization decided
that humanity had to come together in a final, major effort. A global "smallpox news
network," based on residents in hotspots, was created – tackling local outbreaks of the virus.
Cases were encircled, vaccines given, preventing further spread. Smallpox only infects humans,
so if we stopped the human transmission chain, we would starve the virus. The last naturally
occurring infection was in 1977, and in 1980, just shy of 200 years since the first vaccine
was used, Smallpox was declared eradicated. Variola, the scourge of humanity, was dead.
No more children would be killed by it, no more mothers or brothers or uncles or
cousins. It is hard to convey to people around today what an incredible win this was.
One of the cruelest, most dangerous monsters that has hunted us for literally millenia
was slain, by us, apes with pointy needles.
Today we live in a time of enlightenment.
None of us alive today are haunted by the specter of smallpox. This light is not
natural; it was set in the sky by the sheer will of humankind wanting to be
safe from the monsters haunting us. But because we live without them, we forget
that they ever existed and that they are real. That the diseases might reawaken, or
new ones might be brewing in jungles, wet markets or laboratories,
ready to strike us once more. We forget what an incredible gift vaccines
are and how hard we had to battle to get them We are still protected by the light but it is
cooling each and every day, and we owe it to those who will come after us to make sure it doesn't go
out. We killed one monster. We can do it again. This video was supported by Open Philanthropy. Do you want to continue learning about the
fascinating world of biology? We’ve got you! Let’s take a real close look at the human body.
This is an arm. And this is a human cell – the microscopic stage where everything happens. Where
all the important battles are fought and where YOU are constantly built over and over again.
Even though It’s the smallest unit of life, the cell is extremely complex. But don’t worry
we managed to fit everything you need to know on a single poster – and in true kurzgesagt
fashion it’s easy to understand and even easier on the eyes. Grasping a complex topic is much
easier when it’s presented in exciting ways. The poster was researched and designed
in collaboration with molecular biologist James Gurney – so it’s expert approved
and contains all the latest cutting edge science about organelles, their function
and their place in the cellular world. We love bringing science into your home
with our videos and we are so excited whenever we get to do it literally. This is
why we take hundreds of hours to create our science posters – all researched with
care and crafted with love by us here at kurzgesagt. We love having such a curious
audience and we want to inspire you and all the birbs in your life to learn all about
biology, space, humans and life itself. Get the human cell poster now
exclusively on the kurzgesagt shop and support the kurzgesagt
vision of sparking curiosity.
