Hantavirus outbreak, and salmon on cocaine

0:00The Mattress Warehouse Memorial Day Sale is on and you can save up to$1 ,500. warehouse-wide for a limited time. Save up to$500 on adjustable sets from Tempur-Pedic Concealing, or get a Purple King mattress for the price of a queen. Plus, enjoy free next-day delivery and setup. And our exclusive lifetime price guarantee means you always get the best deal. Shop top-brand mattresses, bedding, and sleep essentials. Mattress Warehouse is your destination for the sleep you deserve. Don't miss the savings during the Memorial Day sale for your best night's sleep, only at Mattress Warehouse.

0:49Hello, welcome to this week's Naked Scientist, 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 coming up, Hantavirus breaks out on a cruise ship. Is this uncharted territory for health officials? Also, why salmon might be hooked on cocaine in our waterways and NASA's rovers discover a range of new molecules on the Martian surface.

1:25The MV Hondias, which left Argentina at the beginning of April, has been dealing with an outbreak of a Hantavirus, specifically the Andes strain of the agent, and several of the ship's passengers have been infected, with fatalities also reported. Others are now self-isolating at home. It's unclear how the outbreak began or whether person-to-person transmission of the virus, which has been claimed in previous outbreaks but is nevertheless extremely rare, is behind at least some of the cases. The World Health Organisation has been leading the response and their chief, Tedros Adhanom Ghebreyesus, had this to say at a press conference on 7th May.

2:05Eight cases have been reported, including three deaths. Five of the eight cases have been confirmed as hantavirus, and the other three are suspected. Hantaviruses are a group of viruses carried by rodents that can cause severe disease in humans. People are usually infected through contact with infected rodents or their urine droppings or saliva. The species of antivirus involved in this case is the Andes virus, which is found in Latin America and is the only species known to be capable of limited transmission between humans. WHO Chief Tedros Adnom Ghebreyesus. Mark Fielder, who's a professor of medical microbiology at Kingston University, has been telling me more about hantavirus infections.

3:01these are an interesting group of viruses that emerge basically out of rats and mice and rodents and that's where we commonly see them existing and that's where we get the transmission to humans if we get that transmission from there is two sets of viruses really there's the what we call the old world viruses which are the ones that exist in europe and across asia and the new world viruses which are the ones that occur in places like argentina and chile and brazil and they both present with similar diseases you get the flu-like illness which can then develop in different ways depending on whether you've got the old world strain or the new world strain and the old world strain tends to give you sort of renal problems gastrointestinal problems as does the new world strain but it sort of pretty much ends there and it can be fatal it can give about 10 to 15 percent fatality rate whereas the new world viruses are a little different they can actually develop into much more of a hemorrhagic fever and cause more problems and fatality rate there can be up to 20 to 40 percent depending on the patient and the circumstances so they're quite a diverse group of viruses but the one we're looking at at the moment appears to be a strain called the andes strain of hantavirus and that's one of the new world viruses unfortunately and it looks like it might have been picked up in and around the area of argentina how does it spread normally if it's in the small animals like rats and mice and so on small rodents how do people get it urine or faeces from rodents and that might be direct contact or it might be in areas perhaps in barns or sheds something like that where rats or mice have been and have urinated and defecated and people are sweeping up and the dust that's formed carries the virus um so that's that's one way um it can get into you could also in rare cases get into a patient via a bite from a rodent there have been cases where salivary transfer have got into a patient but that's rare because rodent bites are a lot rarer in some cases we have had human to human contact and transmission when it occurs it is a rare event but when it occurs it's because patients have had very close and possibly intimate contact so we're talking about people sharing a very close space together perhaps kissing lying close together and breathing so that one inhales the other's breath so as to speak so there's a number of different ways but principally for the rats and the mice it's via the urine in the faeces.

5:21How does it actually cause disease? So once it goes in you're saying it's usually breathed in that's going to be a respiratory infection so how does it cause disease and how does it lead to a fatality when that happens? It gets into the lungs and starts causing damage in the lungs which cause the lungs to be leaky and fluid can enter the lungs and cause effectively something like a pneumonia and that damage and fluid in the lungs starts to limit your ability to breathe it can also cause gastrointestinal distress so patients get an upset stomach and diarrhea and with all the immune response that's going on you get myalgia muscle aches and pains and you get great fatigue great tiredness so all these things brought together is not a great end point as far as the disease is concerned or for you getting the disease and of course damage to your lungs is something the body takes great lengths to try and limit and stop and prevent because your lungs are vital to your survival so it's that damage to your lungs and and ultimately once it's got through your body down to your kidneys that can cause a real problem.

6:20What are the possibilities then to explain how these people on this boat got this in the first place? Yeah this is a really interesting question and it is the question of the day quite frankly because that's one of the things we don't yet fully know We know that some of the patients have been touring around parts of Argentina. We know that several people on the boats have been to rural areas as part of their tour. So there's possibilities there that patients could have picked up some virus, perhaps becoming contact with urine and faeces from the rodents there. And there's been some suggestion that one of the couples have been looking at birds and doing some bird watching, and they went to a landfill site to see these particular birds that they were looking for.

6:59and of course we all know that rodents are very frequent around landfill sites so there may have been contact there but at the moment that's speculation because we don't know there's been some suggestion that it might have been rodents on the boat the boat operators have said at the moment they don't recognize that there are any rodents on the boat i would probably favor this is something that the patient's been environmentally exposed to so they're on land somewhere and taking it onto the boat rather than the other way around but at the moment until a full investigation is done and the full epidemiological studies have done we're not entirely sure how then will they disentangle a source that was ashore or on the boat from some cases arising because someone else on the boat who's already got it perhaps they got it from the shore or the boat gave it to another person because all of these things could be happening absolutely and this is one of the things the epidemiological studies will start to untangle or try to untangle they'll be interviewing the patients and people on board that they can to try and understand where they've been what's their footfall before they got onto the boat and then who have they interacted with if they can remember if that is feasible whilst they've been on the boat so have a couple or a group of people been walking around a waste site looking for particular birds or have they not and if they've not and they only remained in very urban areas where perhaps the chances of coming across faeces and urine from rodents is much less, then it'll start to skew the epidemiological view about where they might have picked things up.

8:29And then if they come onto the boat and there's one person with a very low risk background and one with a higher risk background and they spent a lot of time together and one couple has got the infection from the other, then they can start to see a pattern and a line where we might see a development of the disease via one particular route of infection rather than another. But at the moment, that epidemiological study will be very much underway with all the patients that they can talk to. How should they manage this then? Because to my mind, they've got a boat with 150 people on it. They've had a handful of cases of a disease that might or might not be transmitting person to person.

9:05What's the overall risk that's posed? And what should they do with all of these people on the boat who at the moment are perfectly well, but currently not allowed to go anywhere? I would imagine probably the risk on the boat is moderate. And the reason I say that is because by definition they can't go away. That doesn't mean that they are all sitting there cheek to cheek on that boat, they're not of course, but there is closer contact than there would be if we could send people home. The chances of the virus spreading are a little higher on the boat than they are if they were off the boat, which I think one of the things they'll try and do now is get people disembarked when they possibly can.

9:40They'll do an assessment on their general health and assuming that they are not currently showing symptoms or unwell, then those patients might well will be after a short period of time sent back home if they develop any symptoms they'll probably be contacted daily and asked what symptoms they're showing if they're showing any and if as soon as they're showing any minor symptom they will be taken under medical care and isolated very quickly but i think that's that's probably the the risk level is moderate on the boat and once patients leave the boat and assuming they're all healthy all the health checks are done i think the onward infection risk is very low and what they'd be followed up for the rest of the incubation period which can be eight weeks can't it for these viruses can be a long time for some of them so you might be looking at two months of for someone to sweat worrying that they might succumb to this i think that is likely it's a necessary outcome we need to make sure that these patients are safe both from a public health point of view in terms of spreading the disease onwards and also for their own health and the current stance from health authorities internationally is that while further cases might emerge in the coming days, the overall risk remains low, and this is not the start of an epidemic or a pandemic.

10:52That was Mark Fielder at Kingston University. To our own evolution now, and US researchers have found that indigenous populations in the Andes carry extra copies of a gene involved in starch digestion. It codes for the enzyme amylase. The adaptation appears to have been shaped by natural selection favoring individuals with extra amylase genes during the transition to living at high altitudes and adopting a potato rich diet which happened about 10 ,000 years ago. The findings have been published in Nature Communications and Omer Gökum at the University of Buffalo has been telling me about his study.

11:31We found that indigenous Andeans have the highest copy number of the amylase gene and we linked that to a selection that happened maybe 5 ,000 to 10 ,000 years ago coinciding with domestication of the potatoes. And amylase of course being starch and hence having a gene that helps you break it down would be advantageous. Of course, that's the main logic and that link is very exciting because you have a situation where culturally you're changing the diet and that diet change leads to an adaptive evolution of our very own genes in a population. Let's look at the origin of all this first then. So if nature and the environment people are living in, which is the high Andes where they've got, what, potatoes as their major source of starch, if that's the selection, it must be selecting a trait from a population where that trait already exists.

12:29So where did this high copy number of amylase genes come from in the first place, do you think? The high copy amylase seems to be a specific trait for humans where we have that increase early on in our evolution, perhaps even before we diverged from Neanderthals. But then that variation accumulated. So today, if you look at global populations, We have MLA's gene copy numbers ranging from two copies all the way to 20 copies. And we are finding that Andeans have almost always much higher copies than other continental populations. So if I'm reading this correctly then, hundreds of thousands of years ago, which is pre-us splitting away from Neanderthals, we begin to evolve more copies of this starch digesting gene.

13:23That's in our genome. So the humans that are populating the world have got in their number some individuals with more copies of this gene. And the environments they're finding themselves in might apply pressure so that extra copies sometimes help them. So they end up kind of enriching in certain populations in certain places. That's absolutely right. So if we think then, because the South Americas were one of the last places for anatomically modern humans to get to. So some people get down there in tens of thousands of years ago and they take with them this genetic legacy. There's going to be individuals in their number that have more copies of this amylase digesting gene.

14:09How does that then get enriched? and why do you think it's 10 ,000 years ago that suddenly it shoots up in the population? There are more people in the population with that then. So I think the ancestral population that predates that 10 ,000 year deadline is they already carry the variation but you may actually have some people with two copies, some people with 10 copies, some people with 20 copies. What happened at that time frame is the ancestors of indigenous Andeans separated from other indigenous Americans and they end up migrating slowly but steadily and they start to populate the highlands.

14:49And in those highlands, they ingeniously find ways to cultivate potatoes. And that's a very harsh environment. And that becomes a crop, a tuber, that really determines the calorie intake in these populations. So suddenly you have a population that is taking almost all of their calories from potato-based diets. and in those environments we hypothesize that the individuals that carry much higher MLS copy numbers fare better because they can metabolize starch better, they can control and regulate their sugar metabolism better and that will create a reproductive advantage that leads to the situation that we observe today.

15:33The archaeology can tell us when the people did the things we know they did and when they began to inhabit these areas, when they began to shift their diet in this way. Is there a similar genetic clock running that enables you to show that this genetic change lines up with the archaeology? Yes and that is I think one of the most fascinating things because what we can do with the modern computational tools using whole genome data and contextualizing the MLA's locus within that whole genome data, we can estimate when that increase started to happen and what is the trajectory of that increase. And when it started to happen, it lines up almost perfectly with the domestication of potatoes and the migration of these people into the highlands from their ancestors.

16:23And that coincidence is really fascinating. It's academically very elegant and it's very satisfying to see that interaction and the fact that the two things have aligned, the two strands of evidence have aligned. and it fits into a coherent story. But what are the other implications of this? I have to think about this idea of local adaptation as a major force in shaping human diversity, where we have existing variation that we all share, but some of that variation tilts to one way or the other, depending on what kind of environments that we create for our lives. So I'm curious as to other genes and other parts of the genome that behaves similarly that coincide with other types of environmental or cultural trends.

17:13The other thing that is, of course, important is amylase has been associated with multiple biometically relevant traits. And that means that some populations may be more vulnerable or resistant to certain type of ailments. And these kind of findings will help us to create precision medicine type of leaps in our understanding so that we can have better diagnosis, better treatments, better prognosis for different diseases. It's a brilliant bit of detective work, isn't it? Omer Gercuman there at the University of Buffalo.

18:02the price of a queen, plus free next day delivery and setup, and our exclusive lifetime price guarantee locks in your best price forever. Don't miss it. Shop top brand mattresses, bedding, and sleep essentials at Mattress Warehouse, your destination for the sleep you deserve. Shop the Memorial Day mattress sales for your best night's sleep today, only at Mattress Warehouse.

18:23The 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.

18:41Music 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. And still to come, how NASA's rovers are searching for signs of ancient life on Mars. But first, do stay on the line because we have an environmental story which might have you hooked. And that is because scientists have found that salmon exposed to cocaine and its breakdown products in polluted rivers show significantly altered behaviour. Marcus Michelangeli at Australia's Griffith University exposed freely swimming test animals to drug levels that were very similar to those that fish are encountering in the wild.

19:22And he got quite striking results. When we take pharmaceuticals or drugs, they break down into essentially components, which we call metabolites. Cocaine primarily breaks down to benzylcoginine. And this is the metabolite that we often find with high concentrations in the environment, along with the parent compound cocaine. So that's why we focused on this metabolite and the parent compound cocaine for this study. And how did you actually do the study? We tracked 105 juvenile Atlantic salmon in Lake Vatten, which is Sweden's second largest lake. Some of these salmon were exposed to cocaine. Some of the salmon were exposed to the metabolite.

20:08And then we had control fish exposed to a facade implant. And the way we exposed these fish was that we implanted them with a small chemical implant, which essentially releases the contaminant into the fish's muscles and this means that we could chronically expose the fish and test their behavior over time while tracking them in this lake. And you know that when you do that the fish is exposed to a concentration of drug or metabolite equivalent to if it were just swimming in an environment with a relevant concentration in it. So we actually performed a side experiment as the main experiment was going on to actually test the efficacy of these implants.

20:51And we did find that the exposure in the side experiment did meet our aims of meeting ecologically realistic exposure. How do you know where the fish go and what they do once you put the implants into them and let them go? We used a technology called acoustic telemetry to track the fish behaviour. So essentially we set up receivers in Lake Vatten and we implant the fish with a tag, which sends a signal to the receivers and tells the receivers the location of that fish. And this allows you to get incredibly high resolution location data on the fish's movement. So we were able to detect the fish every 15 seconds as it was moving around this lake.

21:36And so this can give you really fine detail information about how they move and behave within the lake system. And where they go as well. So you can follow them over time because I suppose that's another powerful aspect of this. You can see not just what they do, but how long they do it for and where they do it. Exactly. So if you have high quality information about the habitats in the lake, you can also look at how they use different habitats. In this system, we didn't quite have that information, so we couldn't pinpoint the types of habitats they were using. However, we could see how far they were dispersing in the lake.

22:11So, for example, we found that the salmon exposed to the metabolite actually showed the most dramatic behavioural effects. They ended up dispersing up to 14 kilometres further in the lake than control fish. and they move two times the distance that control fish did per week. So they're more active. They seem to go further. Why is that a bad thing? Any change in an animal's behaviour that is not a natural change is not a good thing. Behaviors have evolved in these animals over a long period of time. So for example, an animal that is moving a lot more than it used to be doing suggests to us that it is allocating energy towards these dramatic changes in movement that it would be otherwise allocating to other important factors in its life history.

23:03And so this can have important implications for not only the survival of that individual animal, but also the population that it's part of and the community that it's part of. What sorts of waters are going to be affected in this way? Is there cocaine everywhere or are there hot spots? and therefore are there some areas where we should focus because there's a high likelihood of particular vulnerability in certain species? With cocaine in particular, we find it all around the world and it's particularly at high concentrations where you find more people, so in our urban centres. And so the wildlife that are living in these environments, these habitats, are more likely to be exposed to drugs like cocaine and, of course, other pharmaceuticals we also find in the environment.

23:50In recent years, we've seen examples of people looking at antidepressant drugs, which we we out, contraceptives, which we we out, they all end up in the water. So presumably this is this is like a canary in the coal mine in some respects. You're showing there is an effect of cocaine. That's one drug, but there are many others that could equally be having an effect. That's exactly right. So many drugs and pharmaceuticals that we take, they end up in our wastewater. water. And unfortunately, at this point in time, many wastewater treatment facilities do not have the technology to adequately remove a lot of these pollutants from our wastewater.

24:29So they end up being discharged into our waterways. So another real hotspot for finding these contaminants is downstream from our wastewater treatment facilities, because wastewater treatment facilities are discharging the wastewater into rivers and creeks. And so the closer the water is to a wastewater treatment facility, the higher we find concentrations of illicit drugs and pharmaceuticals. What do we do about it then? I suppose there's no silver bullet, but the good news is there are ways of mitigating the impacts or reducing our impacts. Cocaine, I suppose, a little bit more difficult because there is already tight regulation.

25:04It's a legal drug. But the main thing that we can do is invest in better wastewater treatment technology. So a lot of wastewater treatment plants in richer countries have better wastewater treatment. So they have a three-step process for treating water. But of course, not all facilities have this three-step process. Some only have this two-step process. And that's where we find these micropollutants being able to escape into the waterways more regularly. Marcus Michelangeli at Griffith University there. And that study was published in current biology. NASA's Curiosity rover landed on Mars in 2012 with the aim of adding to our understanding of whether the red planet has or had in the past the environmental conditions to support the growth of microbes.

25:55Meanwhile, the Perseverance rover, which landed in 2021, aimed to look for signs of ancient life. Since then, experiments have discovered a whole range of organic molecules on the planet's surface, although we can't say which molecules were preserved from Martian life and which were formed through geological processes or originated from meteorites. Nevertheless, their discovery confirms that ancient Mars did have the right chemistry to support life. Amy Williams is at the University of Florida and she's been working on it. So I am an astrobiologist and I'm interested in whether there's life beyond Earth.

26:31One of the ways that we can explore this is by searching for the components that make up life as we know it. one of those things is organic carbon. So searching for those on planetary bodies beyond Earth is one of the ways that we can start to explore that question. And how is that actually occurring? Well, there's a bunch of different techniques that people use to basically detect these kinds of molecules. But the way that my study has worked is that we actually get to do this work in situ or in place on Mars. I work with the NASA Mars Curiosity rover science team. and that mission actually has an instrument on board it that's able to detect organic carbon and so I've had the opportunity to to work with the team to develop an experiment that actually revealed some organic carbon that we've never seen before on Mars and so it's a way of sort of expanding the library of molecules that are we know are present on Mars.

27:28And what are the molecules? One of them, I'll give you a big term here, is benzothiophene. So this is a molecule that's made up of rings of carbon. And that molecule actually has a sulfur element within it. And that actually tells you a little bit about where the organic carbon might have come from. We actually think that it came from meteorites that rained down on Mars billions of years ago. How was it actually formed then? Was it cooked up on the meteor, on the parent asteroid that gave rise to the meteor or did it form when it hit Mars and it was the conditions created during the collision that created it?

28:04It's hard to say. We think that some of the molecules that we saw, so we saw more than 24 molecules revealed with this first of its kind experiment done with the Curiosity rover. And some of the molecules have the same character that you see when you do this type of experiment with a meteorite. And so we think that these organic molecules formed on the meteors in interstellar space. And when they rained down on Mars, those organic molecules were actually able to be preserved over very long time periods. Why did we not see them before? So the experiment that the Curiosity rover performed is the first of its kind.

28:44It uses a chemical that can react with sort of our powdered drilled rock sample. And it has a special capability to break apart the components of the rock and break apart actually more complex organic carbon, like big molecules basically, and break that apart into their little constituent parts. What does this tell us then in terms of the likely prospects of life processes having existed on Mars. Is this a sort of an opportunity to say, well, we know what can form in space, therefore what's probably present on Mars and what might not have come from space and therefore might have been made on Mars and might be significant?

29:24The fact that there was this basically more complex organic matter that we broke apart with this first of its kind experiment, that tells us there's more complex carbon preserved on Mars than we realised previously. We just didn't have a technique to see it until we did this experiment. That's really promising in the search for life beyond Earth because it means that we expect life to make complex organic molecules. And if that is preserved in the rocks on Mars, we've sort of demonstrated that it could potentially survive over billions of years. And it could be detectable with the techniques that we have on board this mission as well as future missions to Mars.

30:04So this is a kind of telltale. It says we can do this. we can detect long-lived species regardless of where they've come from and the technique works. So does that mean that this opens the door to then going after life-linked molecules next then? The hope is that we would be able to search for more complex molecules that could be indicative of life or at least linked to life. One of the molecules that we did see with this experiment, we weren't able to exactly identify it but we have an idea about what it is And it actually is a precursor to some of the molecules that make up DNA, the genetic code within all life as we know it.

30:46So it's not evidence for life, but it tells us that basically the components that we know life needs were present and preserved on Mars in the ancient past. Now you've proved you can do this. Is it just widening the search or are you going after a specific target? So this particular experiment contains a chemical that we had to send with the rover when it launched more than 13 years ago now. And that means that we actually used one of the two experiments on board the rover for the study that I'm talking about today. But what this does do is it sets the path for us to be able to do this experiment both one more time on Mars with the Curiosity rover as well as with future missions.