Virologists on hantavirus, and extreme heat at the World Cup

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0:48All engine running. Absolute genius. Get this. Welcome. Welcome. This is the show where we bring you science. What that essentially means is discovery. Advances. Questions. Research. Technology. Unbelievable. Without further ado, this is The Naked Scientist.

1:36first this week let's catch up with what happened with the recent outbreak of hantavirus aboard the mv hondias the expedition ship carrying 150 people that left argentina at the beginning of but has since seen a number of passengers and crews struck down with this infection now virologists often name new viruses after where they were first found zika virus for instance was initially described in Uganda's Zika Forest, while the Ebola River flowing through what's now the Democratic Republic of the Congo needs no explanation for the dread disease that was documented there. Hantaviruses are chips off the same block.

2:13The original name of the virus family comes from the first one that was isolated in Korea back in the 70s near a river called the Hantan River, hence the name Hantavirus. But within that family there's maybe 60 or more different viruses spread across the world and I'm sure there's plenty more to find. As Cambridge University's Colin Crump so eloquently puts it, hantaviruses were first discovered in North East Asia, with the then newly identified virus linked to outbreaks of what had been a mystery disease among soldiers fighting in the Korean War. There are now more than 30 different known species, and they break down conveniently into two main groups, an old world group in Europe and Asia, and a more recently discovered new world group that circulates in the Americas.

2:55It's this newer group that's behind the present outbreak on the MV Hondius, and it's one species from that group in particular, known as the Andes strain, that's the culprit. Now the natural carriers of these viruses are small rodents, like rats and mice, and it's because we are poorly adapted to these viruses, because we run into them relatively rarely, and because hantoviruses are equally poorly adapted to us for the very same reason, that the infections tend to be severe when they happen. Indeed, mortality rates approaching 50 % are routinely documented with these new world hantavirus strains.

3:30Here's infectious diseases specialist Behuma Tatangi at Emory University. One of the things that has been very well characterised, particularly in the case of the strains of hantavirus found in the Americas, is that the virus has the ability to really affect the lining of blood vessels called the endothelial lining. And what it does is that it renders this cellular lining of the blood vessels leaky. You then have fluid that could potentially leak into the lungs, leading to what we call a cardiopulmonary syndrome in the most extreme cases. So that is why you probably have heard described that individuals may have difficulty with breathing, requiring advanced respiratory support from mechanical ventilation, all the way to something we call extracorporeal membrane oxygenation, which is just a system that allows the blood to be oxygenated outside the body and provide the highest level of support while someone is not able to use their own lungs for that oxygen exchange.

4:35Now, frightening though that sounds, one reassuring statistic is that, as a rule, and probably owing to their poor optimisation for human infection, hantaviruses don't tend to transmit between us. So the World Health Organisation, whom we'll hear from shortly, doesn't think they're a good bet for triggering an epidemic or a pandemic any time soon. But what is known about what happened aboard the MV Hondias? Well, at the moment, we can't say. And as the WHO have reported, epidemiological investigations are ongoing. But there are several possible scenarios. One is that the cases identified so far all acquired the infection ashore and took the infection afloat with them.

5:15A second hypothesis is that perhaps the ship itself is the source via a resident population of rodents, although the company have denied that there are rats and mice aboard. and one would have to wonder why just this cruise experienced the problem if that were the case. A third possibility is that one or more individuals acquired the infection on a bird watching trip to a rubbish tip and then took the disease on the boat with them. Amesh Adalja at Johns Hopkins University. I think it has to do with what activities a human does because you just don't always come into contact with these rodents in everyday life.

5:50So if you look at this outbreak that's occurred on the ship, the first patient was somebody who was bird watching and going to places like garbage dumps and places like that to look for birds, that activity, that human activity, what that person was doing had an increased risk. So where does that leave us? Well, right now, the priority is to identify any individuals with a significant exposure to anyone subsequently confirmed as a hantavirus case. And should a contact become symptomatic, they'll undergo rapid testing. If positive, they'll be moved to a specialised unit for isolation and care. Bahuma Titangi again.

6:24For now, most countries are having the approach that individuals who qualify as high risk, who were in close contact with a probable or confirmed case, will be taken to facilities where they can be monitored for clinical symptoms, tested and potentially also confined and quarantined throughout that period where they remain at a high risk for developing symptoms up to six weeks from their last contact or exposure contact. There are no antivirals or vaccines to block antiviruses, so supportive care is the mainstay, and the best outcomes seem to be achieved when this is implemented promptly. The current stance of health authorities is that there is a very low likelihood that this outbreak will spread any further.

7:10This is based partly on the argument that this family of viruses has existed for thousands of years, been known to us for decades, caused outbreaks and isolated cases over many years and yet produced only localised problems with very little evidence ever of onward spread. Moreover, hantiviruses also seem to evolve only very slowly, making the likelihood of the emergence of a more significant human threat that much less likely. Maria van Kirchhoff is director of emerging infections at the World Health Organization. What I feel confident in is the management of all of these individuals and the active follow-up now.

7:50So I think if we do see additional cases, it doesn't mean that the situation is out of control. It just means that laboratory testing is underway. People will get medical care. We haven't had any more deaths. and while we have had three deaths that are tragic we haven't had any further deaths among the confirmed cases or anywhere else and I think that is a good sign. The people who are in ICU in the Netherlands and in South Africa in Switzerland are doing well so that to me is incredibly encouraging. Maria van Kerkhove there, Director of Emerging Infections at the World Health Organization and we will keep an eye on that story and we will bring you any further information as it's uncovered.

8:33Now in other news, scientists in America have created the first detailed map of the smell receptors in the nose. The study builds on similar achievements in the visual system, hearing and touch, and the findings which have been published in the journal Cell may in the future help to develop better therapies for people with loss of their sense of smell, anosmia, or damage to it, a state called parosmia. Bob Datta is a neurobiologist at Harvard Medical school. Odors are small, volatile chemicals that we sense through our noses, and they're detected by specialized molecules called odor receptors.

9:08And so you can think of odor receptors as being like locks, and odors as being keys. And so when a key mashes to its lock, it turns, and the receptor will become activated, and that allows the nose and eventually the brain to know what it is you're smelling. And the question we really wanted to understand was, are there different patterns of receptor expression in your nose creating a map for smell did previously people think it was just a sort of mosaic then that these receptors that detect things just randomly scattered all over the top of the nose where we do smelling and when a certain smell goes up your nose those receptors fire off and you you say oh i can smell that or did we have some insight an instinct that perhaps there would be clusterings of molecules that detect this group of smells are in one place versus molecules that detect other or receptors that detect other smells are in this place.

10:00What did we think? Yes, so the initial sense from the 35 years of work that people have done trying to figure out whether there's a pattern of receptor expression in the nose largely supported the model in which receptors were kind of randomly scattered about in your nose. I think that's important to realise is that we have a lot of these receptors. In humans, we have about 400 different receptors. And in mice, the subject of our study and the organism in which I work, there are about a thousand different receptors. And so there's so many of these receptors, no one thought it was possible to even build a map out of so many different things.

10:33And so people thought that maybe the sensory neurons in your nose, the cells that are responsible for detecting smells, were just kind of randomly choosing which receptor to express. And so there was a kind of random mosaic, which means that my nose fundamentally is organized slightly differently from your nose. How then have you pursued this to try and work out what the map, if it's there, might be? Modern technologies let us look at which receptors and other genes are expressed in single olfactory sensory neurons, cells in your nose that allow you to smell. And taking advantage of that technology, along with new mapping technologies that let us look at where receptors are in different tissues, we were able to map spatial positions of all 1 ,000 of these receptors very precisely in the mouse nose.

11:24And that revealed a surprising map. So there is a pattern? There is a pattern. It turns out the pattern is, going from the top to the bottom of your nose, there are 1 ,000 different stripes which have precise positions. And each one of those stripes corresponds to a particular odor receptor. So the odor receptors that are at the top of your nose are very different from the odor receptors that are in the middle and different from the ones that are at the bottom. And critically, the ordering of these thousand stripes was the same across all 350 mouse samples that we looked at. And so what that means is that it's very likely that my nose is actually organized in the same way as yours.

12:02That's good to know, or nose. But how is that achieved then and why does nature go to the trouble of doing that? What's the advantage of organising stripes of different zones of chemical detection like that? No one believed that the nervous system was capable of organising a thousand things so precisely. So the fact that it does is a kind of miracle in and of itself. Then given that we have this map now the question is why is the map organised the way it is? And so I can tell you many possibilities, all of which we're working on in the lab today. One possibility is that maybe different aspects of odor chemistry are encoded in this map.

12:41So maybe alcohol molecules, you know, like in beer, maybe those are detected at the top. And maybe sulfur molecules, like in natural gas, maybe those are at the bottom. Another possibility is that maybe odor categories are organized in space. So maybe citrus is at the top and meat is at the bottom. Or maybe odor meaning is organized in the map, maybe things you like are at the top and smells you hate are at the bottom. Any one of those things is possible. We've just begun to scratch the surface of this map. We think that some aspects of odour chemistry may live in this map. There's a lot of work left to do before we really understand what the map means.

13:16The other intriguing thing is that different molecules that are very good at binding onto their receptors versus ones that are not very good at binding onto their receptors, they're better detected when air goes faster or slower. So does the positioning of the receptors also get dictated by how fast the air is moving or how much air is moving over that patch of the nose that does the smelling for those molecules? Oh, that's such a wonderful question. And actually, one of the things that we're looking at, I know what you can think about what you just said is that, you know, there's some lighter molecules, some odors that are really light and volatile, like ammonia.

13:49And there's some heavier odor molecules like the scent of fat, for example and maybe based upon airflow and the weight of odor molecules different receptors are different are differently positioned to optionally detect molecules of different weights and volatilities in the context of airflow and that's definitely something we're looking at right now so if i compare say a dog which a dog's sense of smell is way beyond the resolution of of ours obviously that's why we use dogs to go and find things and people and so on when you add more resolution like that and more smelling ability. Are they basically got the same pattern, but it's just got more receptors or a wider spectrum of receptors?

14:30Or is the organisation different, do you think? So I think it's probably true that the organisation itself is a little bit different. Humans have 400 receptors, mice have 1000. Many dog species have 2000 different types of receptors. So they really do have much more resolution over the odour world when compared to us or even mice. and so it's likely that they not only have more receptors but those receptors are placed in a different order in their nose and that might help them detect different types of smells and organize information about smells a little more effectively than in us. Bob Datta at Harvard Medical School there.

15:08This message is a paid partnership with AppleCard. This is Felix Salmon from Slate Money, and I'm here to tell you about Apple Card. Even as a seasoned traveler, things can still get stressful, which is why I use Apple Card on my international trips. And with 2 % daily cash back on every purchase with Apple Pay, I'm actually earning daily cash as I travel. Instead of coming home feeling like I've drained my bank account, I come back with cash back I can put toward my next trip. Apply in the wallet app on iPhone. Subject to credit approval, Apple Card issued by Goldman Sachs Bank, USA, Salt Lake City branch, terms and more at apple.co slash applecardbenefits.

16:07company 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. Still to come, what the UFO files released by the Trump administration do or do not reveal. But first, there's just a month to go until the biggest football tournament in the world begins. Attention though isn't just on the World Cup itself but on the searing temperatures that the players are likely to experience during the international showpiece. They'll have to cope with extreme heat, thunderstorms and high humidity as well as poor air quality from wildfires in some places during the tournament which is taking place this year across three nations for the first time.

16:55So we wondered how well the human body can cope with these extremes especially of temperature and what impacts might this have on play? To find out, we went to someone who works on this topic for a living and also puts his knowledge to good use personally because he is himself an accomplished marathon runner. I'm Christoph Schwiening and I work at PDN, Physiology, Development and Neuroscience, at the University of Cambridge where I'm a lecturer. The World Cup is for the first time going to be played not in one, not in two, but in three countries this year and two of them are going to have matches played in places that are really hot.

17:32We're talking mid-30s or higher. What constraints and impacts does that have on the human body trying to exercise with that kind of intensity in those sorts of temperatures? That all depends on whether they have practiced or had some experience playing in that kind of heat because it's all about self-pacing. So if you start off a football match at full throttle in the heat, you will warm up pretty rapidly. So within about 15, 20 minutes, you're going to be circulating blood, not just through all your muscles, through your skin as well. And that's going to put quite a strain. You're going to be getting hot and you're going to have a circulating blood volume issue.

18:10So you're going to tire quickly. But I suspect most players are not going to be doing that. They're going to be cautious at the start. They're going to be sweating a lot. It's going to be uncomfortable for them. They're going to be instrumented, I guess. Their core temperatures will be measured. they're having breaks so yeah they're going to get hot sweaty and tired. I suppose if you're diverting a whole load of blood to your skin the purpose being you want to get the hot blood to give its heat away to the environment to cool you down that's blood that is not going to muscles and that's going to impact on performance.

18:44That's absolutely the case so the blood is going to the skin not just to move the heat to the skin but also to supply the fluid for the sweating so these guys are going to be losing about four litres of sweat throughout the whole of the match. And that, of course, means that less blood is going to be available, not just to circulate around the muscles, but also to the brain as well. So if they really go for it and go really hard, then we're going to see some bad decisions out on the pitch, because football is a game of skill, largely. It's not really a running race. There's a lot of kicking and passing and collecting the ball as well.

19:19So all of those judgments start to be becomes slightly critical as the players become very hot, tired and somewhat depleted on their circulating blood. If body temperature, though, is 37 degrees C, give or take, right? And we're in an environment which is about that. Why does it feel hot, though? Because it's the same temperature as you are. You're producing heat. And these guys, when they're running around, they're going to be producing maybe up to two kilowatts worth of heat. So two bar electric fire, they're going to be flicking on and off. and so that heat has to flux out of the body. Now if the environment is the same temperature as your body you're not going to be able to radiate the heat.

19:57You've got to lose all of that heat out as evaporated water. So you've got to imagine this as being turning on your cooker putting a saucepan on the top, putting water in it and it's going to be boiling away furiously. Now that's a small area in the saucepan they're going to be evaporating the water throughout the whole of their skin so they're going to feel hot because literally the only thing cooling them down is the sweating and the loss of heat through the latent heat of vaporization of water. Will the body allow its temperature to rise though? So if you put somebody in that situation and put that sort of demand on the body, will your body temperature rise?

20:33Or will those mechanisms we've been discussing, sweating, radiating heat through the skin, will that keep your body temperature at what it should be? No. So first of all, body temperature travels within a range. So you might wake up in the morning, you might be down at 36 and a half degrees C. And if you exercise intensely, by the time you get to about 40 degrees C, you're not going to want to do any more exercise. People actually get that hot, don't they? Oh, yeah, yeah, yeah. They will easily get up to about 40 degrees C. And for a well-trained athlete, it's not necessarily a problem. But the motivation to generate more heat will drop severely.

21:11So these will be players who will be sweating away and not wanting to really do much other than collect and pass a ball onward. So the brain is self-limiting in terms of how hot you get. But you don't have the heat loss capacity to keep core body temperature at what you would consider the normal resting value. It will rise. One of the things that they have said they are going to do, anticipating that this is going to put pressure on people, is to have little breaks, three minute breaks in the games. Is that enough to make a meaningful difference? Well, that all depends what you do. If you just have an ice lolly or something, definitely not.

21:50But if you're going to plunge into an ice cold water bath, then yes, three minutes you can lose a considerable amount of heat. But you need really special measures. So simply spraying yourself with water, not enough. It needs to be a severe cooling shock. So if they just stand there for three minutes, no, that's not going to have any effect at all. If they plunge into ice cold water, fantastic. They'll be able to bring temperature down by a meaningful, you know, 0.2, 0.3 of a degree C, which will give them a bit more headroom to work a bit harder in the next period. Can you train to be better at controlling your temperature, though?

22:27So if you're a team that play in Mexico in these sorts of temperatures all the time, can you adapt? As in, do you get better at sweating and that kind of thing compared to, say, I don't know, say Antarctica had a team. I bet they wouldn't sweat that much, right? But do you find that you adapt and therefore there is a degree of accommodation already so that teams could be an advantage if they play under those conditions already? OK, Chris, I think you're falling into a trap there of thinking that just because people play in a cold environment that they're not going to adapt to heat. So you two in Cambridge here, where it's relatively cool at the moment, can really adapt your thermal control systems very well.

23:07Just layer up a little bit and you will tune up those sweat glands. So drive the sweat glands and also modify your brain. As you get hot, your brain will modify its feed forward responses to thermoregulation. So you will start sweating much earlier as soon as you exercise. So heat acclimation doesn't require a footballer or an athlete to be in a hot environment. They just need to make themselves hot. And these athletes, these football players will be heat training right now. That puts a whole new spin on the term fever pitch, doesn't it? Physiologist Christoph Schreining there. The Trump administration have released files on what has been called Unidentified Anomalous Phenomena, or UFOs, to you and me.

23:52The documents include descriptions of objects spotted during NASA's lunar missions and even images and videos of recent sightings in the Middle East. David Whitehouse is a leading science writer and broadcaster and also author of the book that considers our place in the cosmos alongside our possible ET neighbours, The Alien Perspective. So what does he make of this latest disclosure? Well, actually, I must say I'm really rather disappointed, not only in the files that have been released, but the organization, the American government that's released them. Because some of these files are, if I can put it, rather dumb.

24:29You can look at them and experts within minutes of them being released had explanations for practically all of them. So how come the War Department, responding to President Trump's initiative to release everything it has about strange objects in the sky, release things which can immediately be interpreted and explained when they're supposed to be the experts? Well, what sorts of things, David? What jumped out at you? One thing, which is obviously a balloon floating above the water. And you can see the string from the balloon moving around, being pulled around by the tide. There's another one, which is obviously a flare being dropped by a parachute.

25:13And the interesting thing with that is that the flare is so bright, it's produced what's called a diffraction pattern in the camera that's looking at it. And the decraption pattern is a symmetric star-type object, perfectly understandable. And also, the strange objects which are supposed to have been seen on pictures taken on the surface of the moon, on Apollo 12 and Apollo 17, there's a couple of pictures of the lunar horizon, and there are faint light smears in the distance. and so-called UFO experts have been talking about objects orbiting the moon and isn't this strange? But these are obviously film defects and if you look at other Apollo pictures, you can see similar pictures.

26:02Now, the pictures from the Apollo missions are absolutely superb because the cameras were specifically designed for this, but during the printing process back on Earth, there was occasionally a bit of dust, a bit of smear, etc. And this is well known. So how is it that the War Department can release a series of pictures, fuzzy blobs, which are fuzzy blobs, you don't know what on earth they are, but the rest of them are so obviously explainable? It's a puzzle to me. Didn't Buzz Aldrin say he saw something? All astronauts have reported strange things. On the first American to orbit the Earth, John Glenn, he reported strange objects like fireflies, and that is mentioned in the UFO reports.