Health and medicine
Understanding the Ebola virus outbreak
Dr. Rishi Desai is a pediatric infectious disease physician and former epidemiologist with the Centers for Disease Control and Prevention (CDC). Created by Rishi Desai.
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- At2:35, we know that the first person to obtain a virus is known as the 'Index Case', but can we track the very first Index Case, to find out exactly how the Ebola virus was formed?(10 votes)
- From the author:The very first index case of this outbreak was thought to be a 2-year-old child who died from Ebola in a remote village in Guinea.(16 votes)
- Is it possible that someone infected with Ebola could be immune due to the virus mutating inside them?
And if this is possible. could doctors reverse engineer the mutation for a vaccine?(9 votes)
- well it is actually possible for doctors to reverse engineer the mutation but the ebola virus is way too complicated for such a thing. this is exactly what they are trying to do but they still cant make a vaccine, showing the immense complexity of this virus. And for the first question, no, the people who have been infected are not immune to this virus. Viruses mutate only when they are passed from one body to another as it will receive new genetic coding in the new body. however, fruit bats are shown to be immune to this virus.(10 votes)
- So, is this virus like chicken pocks, or mono, where you should only get it once, or twice, staying in your system, or is it like the flu, where you can get it several times over a lifetime and it floods out of your system?(6 votes)
- From the author:Based on previous outbreaks, it's thought that survivors of the infection develop immunity that lasts about 10 years.(10 votes)
- Why would you dismiss 'airborne' so quickly? Droplets can go very very small, so they can move with the wind. In a small droplet could fit tens, maybe hundreds of virus particles.(2 votes)
- From the author:Based on what we know, it seems clear that the virus spreads through bodily fluids. If there is evidence of individuals getting sick without any bodily fluids involved, then epidemiologists will have to think through other routes of transmission (e.g. airborne). At the moment, that isn't the case.(11 votes)
- Wait couldn't. A droplet be carried by wind? Why would u say it isn't airborne?(3 votes)
- When you sneeze, you disperse droplets of saliva. Not all droplets are the same size. The smallest ones are so small, that they immediately dry up in mid-air after the sneeze. These dried out droplets, AKA "droplet nuclei," are so light, that they can stay afloat indefinitely (look up "Brownian motion").
Since ebola is transmitted by direct contact with bodily fluids, the virus isn't infectious as a droplet nuclei, therefore ebola cannot be transmitted through the air!
In other words, your understanding of airborne transmission is correct, except you confuse droplets with droplet nuclei...droplets cannot be "carried by the wind."(6 votes)
- Why Ebola has not any vaccine to kill them from human body? I heard we have some vaccine for experiment to animal, but I'm not sure that can help us. If it outbreaks to other continents such as Europe, Asia or America. How can we protect ourselves from Ebola ?(4 votes)
- It will probably not outbreak in developed countries, because developed countries have advanced healthcare systems.
Also, remember that we have not had an Ebola outbreak in a while and only now are we able to obtain samples.
Now, Ebola can only be spread through bodily fluids, so here's what my advice is: Don't manhandle other bodily fluids, don't go to West Africa, and stay away from dead bats.
Also, Ebola is only contagious when one is symptomatic and should've sought medical care.(4 votes)
- what do they do with the dead bodies with ebola , do they bury them because i think that would be dangerous(4 votes)
- Can you get Ebola through your skin?(3 votes)
- how do bats get this ebola virus?(4 votes)
- Right now it is unknown,but some scientists think that the bats got the virus from a cave in Africa. Sorry but I don't know the name. There is a lot of info. in the book called Hot Zone its really interesting.(1 vote)
- If the person that first caught the disease is called the index case, then what do you call all of the people he transmits the disease to?(2 votes)
- you call that person patient one. patient zero is known as the index case(2 votes)
- [Voiceover] So, Ebola virus disease has been on the news and today is September 16th and I just want to mark that on the calendar so we can keep track of kind of where things are as they stand today. And these Western African countries are kind of where we're seeing the disease. Nigeria and Liberia, Sierra Leone, Guinea and also Senegal all combined have more than 4,000 folks that have been sick with Ebola and actually over 2,000 people have died of Ebola. And I just want to contrast that with kind of geographically kind of where we've seen past outbreaks that are big. And when I say big, none of the past outbreaks have even compared with the size of the current outbreak. But also the geography is different. You see, in the past it's been more Central Africa. And so, these are kind of two interesting points about the current outbreak. And while we're talking about Central Africa I thought it would be kind of worth noting where the name of Ebola comes from. Actually there's a river down here in Central Africa back in 1976 there was the first outbreak that we tracked and it was actually named after the Ebola River because that's the region where this was first noticed. So, this current outbreak to understand it in its magnitude I think it's useful to kind of take a little bit of a larger view and understand how it transmits or how it spreads in the natural environment, and usually these guys that I'm kind of shading in green. These guys are thought to be kind of one of the animals out there that may be kind of spreading the disease around. So, fruit bats are one of the culprits that people suspect and they also actually get sick with Ebola. So this one I kind of sketched in green and when they get sick they can spread it to other bats in their bat community. And this becomes then, the community because a natural reservoir. We call this natural reservoir of disease or of virus and this is where it kind of circulates normally. And so, we wouldn't even think about Ebola if it was only affecting bats. Probably wouldn't worry about it too much but what happens that every once in a while it affects a human. And the way that this might happen is let's say this person goes in their front yard and they notice a dead bat or a sick bat and they try to care for it and they might get some blood or stool from that bat on their hand, and they can kind of go into a wound, maybe have a cut or it can go kind of in their mouth or if they rub their eyes or nose. So all of a sudden the virus now has a way into the person and so that's kind of how we think that first person might get sick. And that first person we actually have a special name especially if there's an outbreak and that name is an Index Case. We say that this person is the very first person who got sick with the disease here Ebola. And now looking at our calendar, if this person got sick on the 16th today then their first symptoms are not gonna be today. They're gonna happen in a couple of days all the way through three weeks. So really, kind of a long window in terms of when their first symptoms might happen. It could be this month, it might even be all the way through next month because the seventh of October would be three weeks. And generally, we notice that symptoms happen kind of in this window I'm gonna draw right here. So seven to 10 days. That's when their very first symptoms start to appear. So they're not immediate and the first symptoms are kind of vague. There are things like, you know they might feel a little feverish or they might get like kind of a little headache, maybe some muscle aches. So, kind of just general symptoms, not feeling very well and at this point people think, "Well, you know, maybe it could be anything, "some flu or something." So they don't usually go and try to get medical help. But then what happens is that the virus kind of spreads through the immune system and starts getting into all sorts of different tissues and it can cause problems in their stomach, they might want to vomit or have diarrhea. It can go to their lungs, I'm shading in their lungs. They might you know, start coughing. It can cause rashes, it can cause muscles aches, it can cause redness of the eyes, conjunctivitis we call that. It can also cause inflammation around the brain itself. Meningitis. Or it can cause bleeding of the nose or the mouth, the gums. And in fact, that bleeding is really classic because we think of the virus traveling in the blood and so bleeding is a really important thing to notice because it's very, very transmissible. You know, people can get it from the blood and the word for virus in the blood is kind of viremic virus, virus. In this case, it's the Ebola virus, and emic means in the blood. So when the virus is in the blood we would say they're viremic and at this point they might say, "Well, you know, I want to go "and get the help of a doctor." And so, if they go to get medical help the kinds of things that they usually would get would be like IV fluids if they're dehydrated. If they're having difficulty let's say breathing they might get some oxygen. If their blood pressure is low they might get some medications to help their blood pressure kind of come back up to normal. So these are the kind of things that people do and you know, in Western Africa they have all these support out there. You know, they have medical tents setup to kind of help people that have Ebola and so all the care they're giving is considered supportive care. And there's no real specific anti-Ebola medication. Again, we're here on September 16th and people are researching it. But at the moment there is really just supportive care to help people that are sick and nothing specific that targets the virus. Now the worrisome thing, this is now just a... I want you to just kind of wrap your head around this is that with supportive care, what we're seeing in this outbreak on average is a 50% or so fatality rate. Meaning, for two people with Ebola one will die. I mean it's a flip of a coin which is frightening. I mean, if you come down with the symptoms and you're waiting to find out if you have Ebola or not or if you just found out, it's a really, really scary proposition that half of the people with this diagnosis are gonna die. And that's exactly the reason why the world is kind of watching and intervening and helping to make sure that we get this under control. So, in addition to the supportive care the other big area that we kind of think about is how do you avoid transmitting the virus from one person to another. So let me just sketch in a second person here. So here I've drawn a second person and the question becomes how does Ebola get from the first person to the second person? How exactly does it move? And the quick answer is that it moves through bodily fluids. So bodily fluids include everything from blood to vomit and diarrhea or stool and these are kind of the big ones especially blood. Very, very infectious. But also stool and vomit because a lot of these patients are sick and bodily fluids can also be things like saliva and sweat. But again, these first few that I've kind of written out are the ones to really keep in mind, and blood in fact is an interesting one. There was a study that I think is pretty cool and kind of illustrates the point where they showed that one drop. Just one drop of blood from a monkey that had Ebola was enough to carry with it a million little Ebola virus particles and that was thought to be enough to infect a million monkeys. So kind of the idea that one single drop could be enough to really decimate a population. So it kind of drives on the point that if there's a drop of blood, just a single drop or another bodily fluid that really gets over, let's say over into this person's hand and they can kind of go from there to if they touch their face. They can get entry into their body or through their nose or eyes or mouth or let's say they have a little cut. It could actually make its way into the blood through that cut. So, a few kind of interesting ways that bodily fluid can travel but really then it gets a ticket into the second person and the second person can get sick. And of course that could happen with stool or vomit as well. Now another question that I think a lot of people ask is what about airborne? You know, can you breathe this stuff in? And that's a big question and the idea I think is literally is it kind of floating in the air? And the answer is no. You know, it's not really like other viruses like measles and some other ones where it's airborne. So let me just cross that out so it's very clear. It is not airborne. In fact, I think a lot of the confusion comes when you think about things like sneezes. So with a sneeze you can imagine like kind of you know, we've all seen those sneezes or had those sneezes where kind of a big droplet of goo or mucus kind of goes out, and you get this kind of shower, right, of droplets and this kind of right around where you're standing. Just right in your immediate vicinity and that's not gonna affect anyone that's kind of standing away from you, and you could imagine maybe in kind of a strange scenario. Let's say there's a person kind of hanging out right here right next to somebody's shoulder and they're just kind of sitting there. They might get hit in the face with one of these droplets and maybe then you could say, "Well, you know, therefore they got hit "and they're sick with Ebola." But again, it's the droplet which is a bodily fluid and not the fact they were just breathing you know, air like someone that was standing away. So that's not a typical scenario and that's why we don't call this airborne. One quick thing I should mention is that you can get virus that kind of hits a surface and if it hits a surface like a table or the floor, it can actually survive on that surface they think for days to weeks. And so it is an important point because then that means that if someone's been in the room you really have to decontaminate that area and get rid of all those little dried up droplets that are sitting on the surface to make sure that that room is actually really quite clean again. So what it boils down to is that the real way to kind of prevent the spread of this disease is to make sure that these folks are isolated if they are sick with the illness and over here all the caretakers they should be wearing protective clothing. They should be wearing gloves you know, to make sure that they don't get blood on their hands. They should be wearing gowns to cover up the rest of their body so that they don't expose any kind of wounds or cuts or anything like that. They should be also protecting their mouth with a mask and goggles as well. And so, this is actually exactly in the nose. So all these should be kind of covered up. And so, even working in these conditions can be really tough. I mean, these full body suits can get very, very hot and it can very, very difficult to work on these conditions. But this is really what you want to see to isolate Ebola from one person not getting to another and in addition to just hospital workers, of course you also have to remember the fact that it's gonna be you know, funeral directors that are working with dead bodies which can actually again spread virus. Believe it or not, a dead body can actually spread for weeks after the person has died. It can be lab workers that are dealing with specimens or family members actually are huge. So, all these different people at risk and by doing this, you basically prevent the virus from spreading and hopefully end this scourge that's happened in Western Africa.