Should we be concerned about Ebola?

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0:40All engine running. Absolute genius. Get this. Welcome. Welcome. This is the show where we bring you science. What that essentially means is discovery. Advances. Technology. Unbelievable. Without further ado, this is The Naked Scientist. Hello, welcome to The Naked Scientist podcast. This is the show that brings you the biggest breakthroughs and talks to the major movers and shakers in the worlds of science, technology and medicine. I'm Chris Smith and today we're going to examine the latest Ebola outbreak in Africa's Democratic Republic of the Congo. What is driving it and how's it being managed?

1:23the international organization médecins sans frontières has said the rapid spread of ebola in the democratic republic of congo has created a deeply alarming situation efforts to control its spread have been hampered by conflict in the african nation and it now has claimed the lives of more than 250 people that we know of. It's also circulating in neighbouring Uganda, and the World Health Organisation has said the situation is outpacing the healthcare response. Here's Bahuma Tatanji, who's an infectious diseases expert at Emory University in Atlanta. Ebola is a virus that belongs to a group of viruses known as filoviruses.

2:04There are four species of Ebola that have been demonstrated to cause disease in humans. These are RNA viruses, that are circulating in animals and get into humans through zoonotic transmission, so contact with animals that host these viruses. Fruit bats have been implicated, but the host for a lot of Ebola viruses are not fully understood. Once it's established in a human population, another human being who is infected can then pass it on to other humans. And transmission really occurs through direct contact with bodily fluids from an infected individual. So generally people at their most infectious when they're actively ill with the virus.

2:50Although I have heard people talking about when you get big outbreaks in people, it can then endemicise in the human population. You get almost human carriers because there have been documented cases of men passing this on through sexual contact many months after they've themselves recovered to partners. That is correct. One of the things that Ebola viruses have been demonstrated to do is that they can persist in individuals who are fully recovered from the illness. And one of the sites where they persist is in the semen. We call this immunologically advantaged sites, so sites where you may not actually have the immune system capable of completely eradicating and eliminating the virus from the body of the individual who has recovered.

3:38And in these individuals, they have been shown to have virus in their semen, which they can go on to transmit many years later after recovering from the illness itself. And actually, this type of transmission has been responsible for Ebola outbreaks in the past. One of the outbreaks that occurred in the DRC was actually demonstrated to have been started by a recovered survivor who transmitted the virus sexually to their partner. But I would caveat that with the fact that although we know that this persistence happens, the instances in which it goes on to be sexually transmitted are fortunately quite few.

4:20We remember that in the Ebola outbreak that occurred in West Africa and lasted over two years, there were close to 30 ,000 people that were infected with the virus. But it's almost been over a decade since that outbreak. And fortunately, we've not had multiple cases of sexual transmission. You say there are four strains of Ebola that cause human disease. How similar are they to each other, those four? The Ebola viruses that cause disease in humans are actually quite distinct species from each other. For example, the virus that is causing the outbreak currently in the Democratic Republic of Congo and Uganda is called the Pudinbuyo virus.

5:05And when you compare its genetic makeup with the Zaire virus, which is the more common Ebola species, and which has caused the most outbreaks in history, they actually differ in their genome by 32%, which actually crosses the threshold to make them completely different species from each other. And when you compare this to the Sudan virus and also to the Thai forest virus, which are the other two species that have also caused disease in human populations, these viruses are quite distinct and separate from each other. So ranging between anywhere between 25 % to 35 % difference in their genomic makeup.

5:44Does that frustrate efforts to make vaccines? And does that frustrate efforts to test for the viruses? Absolutely. Most of the vaccines that we currently have available for Ebola viruses, we have two licensed vaccines, which target the Zaire species. And the target is the glycoprotein a surface envelope protein that is utilized to actually make the vaccine. And because the viruses differ so much from each other, if you develop antibodies that are specific to the glycoprotein of the Zaire virus, it is unlikely that these antibodies will be able to neutralize Sudan virus, or buddingbuyo virus or typhoros virus.

6:31So each of these Ebola viruses actually require a vaccine that is tailored to their particular proteins, particularly the surface envelope protein, which appears to be the one that is most important for neutralizing antibodies. The same goes for testing. A lot of the testing targets, again, target proteins that are at the surface of the virus, the envelope protein. So you would imagine that if you have a test that was optimized to be able to detect the envelope protein of the Zaire virus, it would perform less well for the Sudan virus, the Budimbuyo virus, or the Thai forest virus. And that is exactly what happened in this outbreak.

7:15A lot of the field tests that are easily deployed to detect Ebola in the population when it is suspected are currently really specialised for the Zaire virus, which is the more common form of the Ebola viruses. So when this outbreak occurred, the field test did not pick up on the Budimbuyo virus because it could not detect the target. When a person's exposed, how does the virus, regardless of what particular species it is, get in and infect us? When someone is exposed to the body fluids of an individual who has Ebola, the virus really targets the immune cells, notably macrophages and dendritic cells, which are then the cells that allow it to have access to the liver, the spleen, and then subsequently spread and disseminate to other body organs.

8:10And once it becomes disseminated, It's, again, a type of virus that likes to target the interior lining of blood vessels, known as the endothelial lining. So you get lots of vascular damage. You also get a cytokine response that is massive. And so these individuals have lots of inflammation, leading to symptoms like florid diarrhea, vomiting, weakness. And in rarer cases, some of them actually have multi-organ failure. and hemorrhagic complications. How does it get into a person in the first place though? Is that through a person swallowing virus, splashes onto eyes, cuts in the skin? What's the routine?

8:56Individuals will get exposed usually when they're providing care to someone who is infected with Ebola. It's for this reason that 70 % of deaths happen in women because women are the primary caregivers. So in the act of providing care, you might have splashing of infected body fluids from an infected person into the mucosa. It could go through the eyes. It could go through micro cuts in the skin. So it's really that direct contact with infected body fluids. And if these cross the mucosal barrier, then an individual will be able to get infected. Behuma Titangi at Emory University in Atlanta. To catch Ebola, of course, you have to have contact with it in the first place.

9:42And as Behuma just pointed out, Ebola virus is a zoonosis. The outbreaks are launched from an animal reservoir, most probably bats. But how does this happen? And what turns a case or two into hundreds or even tens of thousands of human infections? David Matthews is Professor of Virology at the University of Bristol. Ebola is a virus of probably fruit bats. It doesn't make them particularly ill. People have experimentally infected fruit bats and they don't seem to get ill, but they do excrete the virus in their urine and their feces and the bat itself is contaminated. So we think that the bats are passing it around themselves and to them it's not really a disease of great concern.

10:25And that's quite a typical process when viruses spill over from the animal kingdom into humans is that typically the virus is usually not a great concern in its natural host animal day of a peaceful coexistence for the most part. How then do we think it gets from that bat host into other species like us? There are a couple of main routes that we think are likely. The first one is bats hang around in trees, they urinate, they defecate, and that contaminates the ground and fruit around them. Or maybe they try and eat some fruit or they sort of get saliva on it and that fruit drops to the ground, maybe somebody picks it up or they pick up something that's become contaminated with the virus.

11:04That's one possible route. Another one is that they're roughly the size of a small chicken. So sometimes people catch fruit bats and butcher them and eat them. And in the butchering process, of course, you'd be exposed to the blood and saliva, etc. from that bat. Do other animals get Ebola then? Because I'm just thinking that our primate relatives, for example, they're going to overlap in the environment with those bats as well. they'll probably do many other things we would do they might eat them from time to time they might eat that fruit they're discarding they'll snuffle around in the ground where those bat faeces and urine deposits are going so do primates get it too absolutely and i think one of the worst affected animals is uh gorillas they certainly can catch it and it certainly has been a problem in their gorilla population that's and that is a known uh issue there are other mammals that are thought to catch it in around africa but i think gorillas are able to stand out sort of collateral damage of these sorts of outbreaks so they certainly get it and they certainly get very ill.

12:01So what sorts of factors then tend to provoke this to happen because if Ebola's in the bats all the time being carried by them we don't tend to see Ebola all the time we see sporadic outbreaks so why do we see that pattern? That's a really good question so we don't really understand how Ebola and bats interact with each other one idea is that perhaps there's just sporadic outbreaks of Ebola amongst bats. So you get an outbreak, a number of bats are infected, and then they recover their infection, and then they're no longer infected with Ebola. So that's why only on occasion do you get situations where bats can contaminate things and then that spillover event occurs in humans.

12:40What human factors then make it more likely that we will overlap in the Venn diagram with what we're doing, with what the bats are doing, and what Ebola is doing to get that intersection of all three and get a human outbreak? I think at its heart there's just more people population centres are growing we've got more people that needs more space so they spread out into the surrounding areas and that means clearing areas of wildlife and forest and so on and so forth so it's just an ever greater interaction of people with the environment around themselves and that includes the wildlife that live there normally and the number of times you sort of increase that rate of interaction, more likely it is there's going to be a situation where a bat happens to be infected with Ebola and that bat accidentally contaminates a person and that starts an outbreak.

13:29With your work in West Africa during the 2014 outbreak, once it got into humans, what happened next? What do we think the factors were that meant that it then took off? Because presumably there are people, given how big the range of Ebola is and the range of humans, and the range of bats, there are going to be people potentially running into this quite often. So why do we get these sporadic outbreaks that then turn into hundreds of people? And in the case of 2014, tens of thousands of people? Again, really good question. So in terms of what actually happens in the event, we really don't know. There could be hundreds of possible spillover events, but only one of them actually turns into an infection that succeeds.

14:10So it is possible, actually that people are exposed to Ebola more frequently than we think. It's just that, you know, the genetic makeup of the virus that they're exposed to isn't conducive to infecting humans because during an average infection in a bat or in an individual person, the virus will make mistakes copying its genetic material. And it's possible that you just have to be really unlucky and that the bat excretes a version of Ebola, which has the capability to gain a foothold in humans. But I think the issue in West Africa then was once the outbreak started, it got into the large population centers very quickly.

14:46In the past, it was usually outbreaks were confined to villages. It took longer to recognize that it was Ebola. And then you found certain events such as, for example, funerals being real hotspots for spreading the disease around. People come from all over the place to a funeral, obviously. And then if they get contaminated at that funeral by making contact with an infected dead body. They then go back to their places where they've come from, back to their homes, back to their families, which could often be hundreds or thousands of miles away. And that enabled the virus to spread quite quickly into other population centres.

15:18The University of Bristol's David Matthews. So the worst has happened and the virus has again jumped the species barrier and begun to circulate in human populations, this time so far in the DRC and neighbouring Uganda. So how do scientists size up the scale and trajectory of a situation like this and predict what might ultimately happen? As Ruth McCabe, who's an epidemiologist at Imperial College London, explains, one big problem is that very often outbreaks have already reached significant size before we realise what's happening. Her work shows that what is being reported in terms of caseload and the reality are quite some distance apart.

15:58So with all infectious diseases, there is always an element of underreporting that's really important to keep in mind. To be counted as a case, you need to have either shown symptoms, you need to have presented yourself to healthcare, you need to test essentially to become sort of a confirmed case. So with that in mind, we know that with the data that we have, it's only sort of a subset of the total burden that we are seeing. So when this outbreak first emerged, I think it was around 200 suspected cases that were initially being reported. Now, by pulling together information that we were seeing from different sources, we were able to estimate that actually at that point in time, it was not impossible that we were close to almost a thousand cases at that point.

16:47So, you know, quite a big difference. Fivefold bigger outbreak than actually we knew the numbers told us. In the beginning, absolutely. Now, there's a huge sort of time dependency here that's really important to take account of, because since the alarm has been signalled, testing capacity has been scaled up. And as part of the response measures, there is active seeking of cases, which then means that, you know, we start to have a larger number of cases being captured in the data. But in those initial phases, yes, it can be quite like a big difference between what is being recorded and what the true scale actually is.

17:29Do we know, I presume we have some insights from the previous Ebola outbreak, when you get these sorts of numbers, the rates at which these sorts of outbreaks start to grow? Now, what's really important to think about is I guess there's almost two processes that are going on here. So firstly, we've got the disease transmission process, and that is what's happening in the affected areas. Now, the way that we learn about that is from that process of gathering the data. And those don't always line up exactly. So since the outbreak started, resources have been obviously put into the affected areas.

18:09so that might mean that you know the rate at which we are learning information the rate at which the data set is growing might be faster than the rate at which the epidemic is growing itself and that's why it's really difficult in this early stage of the outbreak to get a good answer of how quickly things are actually spreading. So the present situation is significant and it could grow quite a bit more yet that was Ruth McCabe at Imperial College London on the importance of getting the numbers right to understand what it is that we're up against. Hi, this is Brooke DeVard from Naked Beauty. I am always looking for ways to elevate our daily rituals and the Kohler Smart Toilet is proof that design changes everything.

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19:24The Naked Scientist podcast is produced in association with Spitfire. Cost-effective voice, internet, and IP engineering services for UK businesses. Find out how Spitfire can empower your company at spitfire.co.uk Music in the programme is sponsored by Epidemic Sound, perfect music for audio and video productions. This is the Naked Scientist podcast with me, Chris Smith. Today, the Ebola outbreak in the Democratic Republic of Congo and our efforts to manage it. We now know from the programme so far what Ebola is and how it can cause outbreaks. So next we're going to explore how to treat it and prevent it.

20:08That is easier said than done. The mortality rate in Ebola cases is often over 50 % and a further frustration with the present outbreak is that the existing drugs and vaccines we have target the more common Zaire strain of the infection which will potentially limit their use. So what should we do? Michael Marks is from the London School of Hygiene and Tropical Medicine. First is about the management of the individual themselves which people will often refer to as the index case and one of the priorities is to have the index case managed in a safe environment so that normally is in what we call an Ebola treatment centre and this is a place where we can really concentrate on managing the person thinking about all of the infection prevention elements so thinking about avoiding onward transmission from the index person to the healthcare workers providing.

21:00So that's thinking about the spaces in which the patient is positioned, the type of personal protective equipment that the staff are using, and the sort of way in which we need to approach doing all of the procedures on that person, so to give them care and treatment. And then separately, when we identify an index case, we also need to think about who all of their contacts are. And so that's delivered by a different team but there's normally a dedicated effort about thinking about who are the people that this index case has been in contact with over the preceding period of time and then those individuals will go through a process of what we call contact tracing where they're followed up and they're monitored so that if any of those individuals develop symptoms of ebola they can be detected early so we've got these two prongs if we just look at that index case first what can we do for a person confirmed as having acute ebola there's what we call supportive care so we know that patients with ebola often they are losing a lot of fluid from their gut they're losing salts from the blood they may have other infections such as malaria at the same time and so a lot of what we want to do is optimizing that supportive care so that's about carefully replacing the fluids replacing the sodium and the potassium the important salts in the blood treating other infections that that person might have such as malaria and then separately there is thinking about whether or not there are specific medicines that might treat ebola now for the most common ebola virus that's zaire ebola virus there are now a number of effective medicines which we know can reduce mortality from the infection.

22:47And those are predominantly cocktails of pre-made antibodies. So those are the proteins that your body normally makes as part of its immune response. And what we can do is we can essentially infuse into your bloodstream this cocktail of antibodies, which will bind and help kill the Ebola virus. And for Zaire Ebola virus, for example that has been a very successful strategy and shown to improve outcomes we don't currently know if any of the medicines that have been developed and tested for zaire ebola virus will work with the virus that is causing the current outbreak and so that will be a real focus in trying to identify treatments that we can give alongside supportive care is the vaccine any use in this context because the vaccine must suffer from the same problem presumably because that also was made in response to the huge outbreak in 2014 and targets the Zaire form of the infection.

23:44So that's correct. Again, when we think about the role of the vaccines, the vaccines are not really for individuals who have already become unwell, but they are about preventing infection. So for example, if we had an effective vaccine, when we did that contact tracing that I was describing, we would be thinking about offering vaccination to all of those contacts to reduce their risk. Now, there are a number of vaccines now available for Ebola, but nearly all of those vaccines have been designed to target the Zaire strain. There is a vaccine very similar that's been developed against the Sudan Ebola virus, but there is not yet a vaccine that has been tested against the Bundabhaya strain, which is causing the current outbreak.

24:30And so again, we have some of these questions about how quickly can we develop a new strain-specific vaccine? And even if it wasn't originally designed for this particular strain of Ebola, might there be some partial cross-protection from the existing vaccines? Because if there was some partial protection, that is a vaccine that already exists that we could roll out more quickly. So that I think people suspect that there may be not very much cross-protection because they're quite different viruses but you could imagine that even a small amount of cross-protection with an infection that's as dangerous and that has such a high mortality as Ebola might still be worth considering.

25:13Michael Marks at the London School of Hygiene and Tropical Medicine. Of course there is an even worse scenario which is that the disease does begin to spread internationally. Now that is unlikely to happen at scale for various reasons but modern air travel does mean that you can be on the other side of the world well within the incubation period of any infectious disease that we have discovered to date which means that countries with major international air hubs like the UK are at risk of seeing cases crop up. Now this happened periodically during the 2014 West African outbreak when international teams of nurses and doctors travelled home after helping people there.

25:50So what plans are in place should the worst happen? Well, here's the UK Health Security Agency's Colin Brown. It probably is rare for that scenario to happen. We've had lots and lots of large Ebola outbreaks over the world, particularly the West African outbreak over a decade ago now. And the number of cases that were borne by people getting on a plane and travelling rather than having been medically repatriated were very low. But it does remain a possibility. The health service itself is very well rehearsed about how it would respond. People would be isolated appropriately. Various tests that they would need would be processed in a very secure manner to protect all the different types of healthcare workforce, including the laboratory staff that would be doing the tests.

26:36There's always a chance that someone doesn't volunteer information and that they would be arriving at a healthcare facility perhaps without saying anything. How easy is it to catch Ebola? Ebola? It's not very easy to catch Ebola in the early stages when people are in the prodrome, which is this sort of bit of the illness where people are just beginning to get unwell. It resembles a flu-like illness in the men. They have a temperature, they feel very achy. It is not very contagious at this stage. It is more contagious when people have bodily secretions, copious, diarrhea, vomiting, and then the thing that people pay most attention to, sometimes there's bleeding associated with it, but that's a very late stage.

27:14Presumably, cases in a country like the UK would be in a specialist facility. We wouldn't just put them in a side room on a hospital ward, for example. They would be in a dedicated isolation unit for diseases like this. That's right. So we have a network of high consequence infectious disease units. My own hospital, the Royal Free in London, is one of the primary centres that would care for suspected Ebola patients. I think if people were known in advance to have potential exposure, they may be directed to one of those centres just in case someone tested positive, or at least will be cared for in a specialist centre of infection, and then will be transferred to a dedicated high containment unit if anyone tested positive.

27:55So the environment through which high consequence infectious disease are managed in the UK is very well regulated, there are clear pathways, and the approach is very different than for other diseases. There also is public health mechanism that accompanies that. So if they've been in contact with anyone else, immediately enter a contact tracing system and everyone who potentially is being exposed is rapidly identified and made contact with and appropriate follow-up arrangements are made. We had a chance to rehearse, I don't mean in an artificial way, I mean have we had the real deal, not necessarily with Ebola but something a bit like Ebola with the same sort of trajectory of spread, the same sort of infectivity, where we've been able to put any of these measures to use or put them into action to see if what we think should happen does happen?

28:42So we've had a lot of exposure to the family of diseases that Ebola belongs to, viral hemorrhagic fevers. The West African outbreak was the biggest in the world. Nearly 30 ,000 people were affected at that point. And we had a number of UK civilians with Ebola, mainly healthcare workers. But we have had other viral hemorrhagic fevers. Lassa fever is the big one, where we've had a number of people contracted and being diagnosed within the UK, where both the clinical management and the care within hospitals like the Royal Free, and the wider public health mechanisms of rapidly identifying anyone at risk, getting them into appropriate care pathways, getting them into appropriate monitoring through the UK Health Security Agency, that is all very well rehearsed and has been established for a large number of years.

29:29Some countries have announced they're restricting flights from places where the disease is circulating, chiefly at the moment, the Democratic Republic, the Congo. I think the Bahamas is one entity that has said they're going to be looking at this, Canada, another. Is there grounds for doing that? And should we be doing that? Or do you think the checks and balances we already have probably are adequate? The UK would take a very serious view before deciding on doing that. And they would think that the risks to the country would have to be so great that they would deem it appropriate. But that is a view that every country needs to make on its own based on the available evidence and the public health infrastructure available to them.