00:00What makes Ebola so dangerous?
00:03How can a virus overwhelm the very complex defense system of the body so quickly and so effectively?
00:09Let's take a look at what Ebola does.
00:12Ebola is a virus.
00:14A virus is a very small thing.
00:16A bit of RNA or DNA and a few proteins in a hull.
00:20It has no ability to do anything by itself whatsoever
00:23and can only survive and proliferate by infecting cells.
00:27To avoid this, we have the immune system.
00:30The immune system is super complex,
00:32so we developed a visual system that makes it easy to understand.
00:36So it looks like this.
00:38Let's concentrate on the part that's critical to understanding Ebola and ignore the rest.
00:42So, usually, dendritic cells would activate an army of antivirus cells,
00:47support cells and antibody factories that would, together with the guard cells,
00:51wipe out the infection in a matter of days.
00:54But when Ebola strikes, it directly attacks the immune system.
00:58Some of the first cells it takes over are the dendritic cells,
01:02the brains of the immune system.
01:05The Ebola virus enters a dendritic cell by binding onto receptors for cell transport.
01:10Once it's in sight, it dissolves its outer hull
01:13and releases its genetic material, nuclear proteins and enzymes.
01:18In a nutshell, it takes over the cell,
01:21disables the cell's protective mechanisms and reprograms it.
01:25The cell now becomes a virus production machine
01:28and uses its resources to build Ebola viruses.
01:31Once the cell is saturated, it dissolves the cell membrane
01:35and millions of viruses are released into the tissue.
01:39The virus not only prevents the dendritic cell from activating the specialized antivirus forces,
01:44it manipulates it into sending signal proteins
01:47that trick the specialized cells into ending their own lives prematurely.
01:51So the immune system is seriously disrupted and unable to react,
01:56while the virus rapidly multiplies.
01:59We're talking billions.
02:01There are cells that should deal with infected cells, the natural killer cells.
02:05But they also get infected and just die before they can prevent the disease from spreading.
02:10At the same time, Ebola infects the guard cells of the body,
02:14macrophages and monocytes.
02:16Not only managing to circumvent their defenses,
02:19it also manipulates them to signal to the cells that make up the blood vessels,
02:23telling them to release fluids into the body.
02:26Usually this makes sense, but in this case, it just causes mayhem.
02:30All over the body, neutrophils are activated,
02:33awoken by the virus and the macrophages' signals.
02:36They're not very effective against viruses
02:38and should not be involved in this fight and begin to do lots of stuff they shouldn't do.
02:43The neutrophils signal the blood vessels to release more fluid, causing internal bleeding.
02:48Another area of the body Ebola attacks is the liver.
02:52The virus finds it very easy to enter the liver
02:54and it quickly starts killing loads of liver cells
02:57and causing organ failure and more internal bleeding.
03:00And all of those things are going on at the same time.
03:04As the virus spreads, it's like nukes exploding everywhere.
03:08One incident of this in one region would be problem enough,
03:11but now it's starting to happen everywhere at once.
03:14All the mechanisms the immune system has evolved to handle infections work against you,
03:20and the virus continues to spread and spread
03:23and finally begins to infect more and more body cells
03:26while the body desperately struggles to stay alive.
03:29In a desperate last effort to turn the tide,
03:31the immune system launches a cytokine storm.
03:34A cytokine storm is an SOS signal
03:37that causes the immune system to launch all of its weapons all at once
03:40in a desperate kamikaze attack.
03:42This hurts the virus, but leaves behind tons of collateral damage,
03:46especially in the blood vessels.
03:49Paradoxically, the healthier the immune system,
03:52the more damage it can do to itself.
03:54More and more fluid leaves the bloodstream.
03:57Blood pours out of every opening of the body.
03:59You become seriously dehydrated.
04:01There's just not enough blood left to supply the organs with oxygen
04:05and cells begin to die.
04:07If you reach this point, the chance of you dying is very high.
04:11Currently, 6 out of 10 infected die from Ebola.
04:15Wow. Okay, Ebola is nasty.
04:18So it's time to panic, right?
04:20No, not even close.
04:22The severity of Ebola gets papers sold and YouTube videos shared,
04:26so everybody is talking about Ebola.
04:29But currently, the only way to get infected by Ebola
04:32is to come into contact with the bodily fluids of a person who shows symptoms
04:36or from an infected bat.
04:38So, just don't do that.
04:40Ebola has killed 5,000 people since June 2014.
04:44The common flu kills up to 500,000 people each year.
04:48Malaria kills up to 1 million each year.
04:513,000 people every single day.
04:5310 children since this video started.
04:56So, even if Ebola is terrible and scary,
04:59don't let yourself be scared.
05:01The most infectious thing about Ebola is the media hype around it.
05:05You could learn a bit more about the immune system, though.
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