Sep 4, 2020
Transcript
[RADIOLAB INTRO]
JAD ABUMRAD: Hey. I'm Jad Abumrad. This is Radiolab. And today, a story from our very own Molly Webster.
MOLLY WEBSTER: So yeah. So today, we're talking about a medical mystery.
JAD: Oh, good. Let me put on my wool cap then, because it's an important part ...
MOLLY: Oh, he really is putting on a wool cap, folks.
JAD: Okay.
MOLLY: Okay.
JAD: A medical mystery?
MOLLY: Yeah. It starts with a woman ...
JOVERIA FAROOQI: Hello?
MOLLY: Hi. I'm trying to reach Joveria, please.
MOLLY: ... named Joveria Farooqi.
JOVERIA FAROOQI: This is Joveria. How are you, Molly?
MOLLY: Oh, my gosh. Hello!
MOLLY: She works at a hospital ...
JOVERIA FAROOQI: At a teaching hospital in Pakistan.
MOLLY: ... in Karachi.
JOVERIA FAROOQI: It's The Aga Khan University. And I'm a medical doctor specialized in medical microbiology.
MOLLY: Joveria various works in the hospital lab. And so when someone has an infection, she gets sent, you know, some blood or urine or something, and she tries to figure out which bug is causing the problem.
JOVERIA FAROOQI: So the very first month that I was in the lab...
MOLLY: In the fall of 2014.
JOVERIA FAROOQI: ...The third week of October, I found three bugs...
MOLLY: In the blood of three different patients.
JOVERIA FAROOQI: ...Which looked exactly the same.
MOLLY: And like nothing she'd ever seen before.
JOVERIA FAROOQI: Creamy in texture. It had a whitish ring and it had another ring of light brown around it, a white center - and very, very white. It's sort of like when you put UV light on white and it sort of shines with a bluish tinge.
MOLLY: And what she saw wasn't a bacteria or a virus. It was actually a fungus.
JOVERIA FAROOQI: A yeast.
MOLLY: But beyond that, she sort of had no idea what it was.
JOVERIA FAROOQI: I shared it with all my friends who were working in other labs, and I asked them if they had encountered something like this. And they all said no. But the patients were all very, very sick.
FAISAL MAHMOOD: Yeah. Well, so what happened is that we started seeing patients with fever, high white cell count.
MOLLY: So the three patients those samples had come from were all at the same hospital under the care of this guy.
FAISAL MAHMOOD: Dr. Faisal Mahmood. I'm an infectious disease specialist here at The Aga Khan University.
MOLLY: And all three of them were patients in the ICU.
FAISAL MAHMOOD: Older patients, folks who'd been in the hospital for a week or two weeks.
MOLLY: You know, with patients like that, they definitely deal with fungal infections from time to time.
FAISAL MAHMOOD: So the symptoms were really nothing spectacular, nothing weird.
MOLLY: But when he found out that they all came down with the same mysterious fungus all at the same time.
FAISAL MAHMOOD: When it was identified, we were like, okay, that's weird.
MOLLY: Maybe some kind of coincidence.
FAISAL MAHMOOD: But then...
JOVERIA FAROOQI: While I was looking at those, I encountered yet another one.
FAISAL MAHMOOD: Another one popped up.
JOVERIA FAROOQI: ...Exactly the same yeast.
FAISAL MAHMOOD: And another one popped up.
MOLLY: In the same hospital, but this time, not from the ICU.
JOVERIA FAROOQI: And I thought, oh, my God.
MOLLY: Which was really strange because they had never seen this fungus before, and suddenly, it's popping up all over the hospital.
JOVERIA FAROOQI: I would have been OK if it was just one case. Or two cases in a whole year - that's all right. However, to encounter them in a whole - in a cluster is alarming. You know? What's it doing in our hospital behaving so angrily and killing people off? I mean, two of our patients had died by then.
FAISAL MAHMOOD: You know, we just sort of kept seeing them—tuck, tuck, tuck, tuck. I think within six months, we had, like, 19 cases.
MOLLY: And by then, six months in, eight of the patients had died.
JAD: So this fungus is pretty nasty.
MOLLY: Yeah. I mean, the people who get it seem to have other sicknesses as well. But once you got it, the mortality rate's, like, 20 percent to 60 percent.
JAD: Oh, damn!
FAISAL MAHMOOD: And that's about the same time when Joveria sent some strains to the US CDC.
MOLLY: Joveria basically sent them an email and just said, you know, hey, will you look at this thing? And this is when the mystery of this fungus went way, way beyond one hospital in Pakistan.
TOM CHILLER: We were informed by colleagues in Pakistan that they were having a large outbreak.
MOLLY: One of the guys that got that email eventually was Tom Chiller
TOM CHILLER: Chief of the Mycotic Diseases Branch here at the Centers for Disease Control and Prevention in Atlanta, Georgia.
MOLLY: And he and his colleagues pretty quickly identified the fungus as ...
TOM CHILLER: Candida auris.
FAISAL MAHMOOD: They said it's Candida auris. And I'm like, Canda-what? I was like, I've never heard of Candida auris before.
MOLLY: Now, Candida is kind of a big group of fungus. It lives on our skin and in our gut and can cause yeast infections and thrush in babies. But this particular Candida was totally new.
TOM CHILLER: It was first isolated from an ear infection of a Japanese patient.
MOLLY: And that was in 2009, and it was really just causing some sort of goopy goop to leak out of this woman's ear.
TOM CHILLER: On the skin, where we know some Candida species can be, and we didn't think, honestly, much of it.
MOLLY: Until, six years later, they hear from Joveria that this Candida auris is getting into people's blood and causing serious infections.
TOM CHILLER: You know, horrible bloodstream infections and even death.
MOLLY: And so he thought, "Okay, this thing that we saw once that we did not think was a big deal is now killing people. So what's going on?" And so he started poking around, and he came across reports of Candida auris outbreaks in South Korea, in India.
TOM CHILLER: And South Africa had described clusters.
FAISAL MAHMOOD: And we figured - we found that it's popping up all over the world.
MOLLY: And actually, while looking into this ...
TOM CHILLER: Colleagues from London were talking to us about a very similar phenomena with the same organism.
MOLLY: A hospital in London had an outbreak.
TOM CHILLER: To the point where they had to close their intensive care unit for a period of months. So what we saw were that there were essentially four different clades, for lack of a better word, that were emerging in three different continents all about at the same time.
MOLLY: Meaning it wasn't like it started in one place and then went to all these other places.
TOM CHILLER: It couldn't be explained by travel. It couldn't be explained by the - you know, by the fact that these were in some way related, except that they were the same species of organism. They truly were emerging at around the same time in four parts of the world.
MOLLY: So the big question that arises out of this moment is: why now?
TOM CHILLER: Yeah.
JAD: Wait. Just so I make sure I'm getting this. You have one fungus appearing in four totally different parts of the world simultaneously?
MOLLY: Simultaneously.
JAD: Weird!
MOLLY: It's definitely not normal.
SNIGDHA VALLABHANENI: No, it's absolutely abnormal. And, you know, people around the world are trying to figure out how this happened, why it happened, why is it...
MOLLY: So this is Snigdha Vallabhaneni, and she was part of the team at the CDC that was tracking the fungus and trying to figure out what was going on.
SNIGDHA VALLABHANENI: So initially, we thought, like, could - is it possible it's some contaminated medical product or something that got distributed.
MOLLY: Something that got distributed to these hospitals. But then they thought, four different hospitals on three different continents?
SNIGDHA VALLABHANENI: I mean, you don't expect it to be that worldwide.
MOLLY: So it was like, scratch that. Maybe it's...
SNIGDHA VALLABHANENI: The way, you know, different antifungal drugs have been used around the world.
MOLLY: Like, we all use, you know, antifungals in our body, but the more important thing is farms using antifungals where they spray their crops. So it's maybe the fungus are adapting to fungicides, and it's just getting stronger.
JAD: So would it be that the farmers are training the fungus and then those fungus are then somehow getting away from the farm and into the hospitals or...
MOLLY: Yeah.
JAD: Okay.
MOLLY: But that still doesn't explain why it would happen in all these separate places at this one particular moment.
JAD: Why now?
MOLLY: Right. You need something that was happening to all of these fungus in different places at the same time.
SNIGDHA VALLABHANENI: And that's why people are looking for more of this not just environment, but sort of a bigger-picture ecological analyses.
JAD: Meaning what?
MOLLY: Well, I just at this point feel like I should just start talking about dinosaurs.
JAD: [laughs] Wait. Wait. Wait.
MOLLY: It is a little bit of a detour, but I promise it will pay off.
JAD: No, it's - my relationship with dinosaurs in general...
MOLLY: Yeah.
JAD: ...Is I'm like, oh, God, here we go.
MOLLY: There is a lot of history there.
[ARCHIVE CLIP, Kurt Braunohler: Ladies and gentlemen, please welcome to the stage your hosts for this evening, Jad Abumrad and Robert Krulwich!]
[applause]
MOLLY: But trust me, it'll be worth it.
[ARCHIVE CLIP, Jad: What's up, Seattle?]
JAD: To loop everybody in, about seven years ago, we did a live show called "Apocalyptical" that had life-sized dinosaur puppets, traveled to 21 cities. Super fun, but it completely broke us, and we all nearly died.
MOLLY: (Laughter) Yes, it's true.
JAD: Yeah.
MOLLY: But part of that live show is a story that I reported for you guys about an asteroid that hit the Earth and put an end to the dinos.
[ARCHIVE CLIP, Jad: So it turns out, on that day, as the fire was raging above on the surface, somewhere in a little hole in the ground happened to be a furry little animal.]
MOLLY: And about how after the cataclysm, this mammal - small little mammal - crawled out of its little muddy burrow into a dino-less world and became the...
[ARCHIVE CLIP, Jad: Great, great ...]
[ARCHIVE CLIP, Robert Krulwich: Great ...]
[ARCHIVE CLIP, Jad: Great...]
[ARCHIVE CLIP, Robert: Great...]
[ARCHIVE CLIP, Jad: Great, great...]
[ARCHIVE CLIP, Robert: Great...]
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[ARCHIVE CLIP, Robert: Great...]
[ARCHIVE CLIP, Jad: Great ...]
[ARCHIVE CLIP, Robert: Great...]
[ARCHIVE CLIP, Jad: Great...]
[ARCHIVE CLIP, Robert: Great, great...]
[ARCHIVE CLIP, Jad: Great...]
[ARCHIVE CLIP, Robert: Great...]
[ARCHIVE CLIP, Jad: Great, great, great et cetera grandma of everybody in this room. It is true. There was a creature down there. There was a creature down there ...]
[ARCHIVE CLIP, Robert: I thought we should stop there because...]
[ARCHIVE CLIP, Jad: [laughs]]
[ARCHIVE CLIP, Robert: We were getting away with something, and I didn't want to push it too far.]
[ARCHIVE CLIP, Jad: All of a sudden, it was just you and me.]
[ARCHIVE CLIP, Robert: Yeah, though...]
JAD: Oh! I miss Robert.
MOLLY: I know.
JAD: [sighs] Anyhow, continue.
MOLLY: Story goes like this. With dinosaurs out of the way, the idea is that mammals crawled out of the hole, and they just inherited the Earth - so big reptiles out, crafty little mammals in.
JAD: Yup.
MOLLY: But there is a new idea about this fungal friend of ours, this one that we've been talking about, that sort of messes this story up a little bit.
ARTURO CASADEVALL: So here we are in the realm of hypothesis, speculation. We don't really know what happens 65 million years ago or a hundred million years ago.
MOLLY: The idea comes from this doctor and microbiologist Arturo Casadevall at Johns Hopkins University. And he says the first few beats of our story are all good.
ARTURO CASADEVALL: Right. We know that there was a catastrophe. The asteroid hit the Yucatan, and we know that the Earth had a really bad day. And the animals that then follow are - is the age of mammals. So...
MOLLY: Yeah, because I feel like we, like, took down all those dinosaurs, and there was a big hole, and we're like, "Ahh!" And we crawled out of it (laughter).
ARTURO CASADEVALL: Yeah. I think that people thought that, you know, because the dinosaurs were wiped out, that it created a space.
MOLLY: This is absolutely what I think.
ARTURO CASADEVALL: Right. So there is a little bit of a problem with—in my mind with that.
MOLLY: (Laughter) OK.
ARTURO CASADEVALL: And I add that this is my problem (laughter). But I'll show you what the thinking is. If you look at our world today, we still have reptiles.
[ARCHIVE CLIP: A crocodile-infested riverbank.]
ARTURO CASADEVALL: We have alligators.
[ARCHIVE CLIP: This is a Gaboon viper from West Africa.]
ARTURO CASADEVALL: We have lizards.
[ARCHIVE CLIP: A monitor lizard is out hunting, looking for the entrance to the galleries in which the mammals take shelter during the daylight hours.]
ARTURO CASADEVALL: So clearly, some reptiles survived the catastrophe.
MOLLY: There were reptilian creatures that were living in the, you know, riverbank in the same way that the mammals were and got out of the fires and the ash and came out.
ARTURO CASADEVALL: And it's always bothered me; how come we didn't have a second reptilian age?
MOLLY: So you actually have a moment when either of them could have taken the crown.
JAD: I thought the idea was that just - we got lucky.
MOLLY: I mean, we would have had to be really lucky because according to Arturo, reptiles had two big advantages over us straight out the gates, first one being...
ARTURO CASADEVALL: Reptiles, in contrast to mammals, don't need that much food.
MOLLY: Which, you know, is great because at the time, most of the plants had burned up. The planet was covered in ash. There really wasn't that much food. And whereas mammals have to eat all the time, like, reptiles can just chill for a while. So that's definitely a win for reptiles over mammals.
ARTURO CASADEVALL: They also reproduce a lot faster.
MOLLY: The second one is that they just make more babies. They can spread a lot faster. Their chances of survival are greater. So Arturo's like...
ARTURO CASADEVALL: If the reptiles are able to do well with less food and they reproduce faster, why didn't they just take off and create a whole new world which was reptilian, too?
MOLLY: Now, his idea for why this didn't happen, why there wasn't a second reptilian age, is that there was another player on the dino-free stage - a small, invisible, yet powerful player. And to understand, you have to know that before the asteroid hit...
ARTURO CASADEVALL: It was a forested planet that was, in fact, a lot warmer than it is today. There were forests in many parts of the world. The cataclysm is thought to have led to rapid temperatures that fell, and you also had no sun. So imagine a dark, cold world of decaying vegetation. This cataclysm was associated with a massive proliferation of fungi.
JAD: Huh!
MOLLY: And actually, if you look at, like, right above the K-T boundary, that line that demarks, you know, no meteor, meteor, dinosaur, no dinosaur...
JAD: Yeah.
MOLLY: If you look right above there, it's—the soil is filled with spores.
JAD: No [bleep]!
MOLLY: And so everyone knows, it's really well-documented that it was...
JAD: Wait. So at the layer after the impact...
MOLLY: Yes.
JAD: ...There is a layer one or two up which is filled with fungi spores?
MOLLY: Yes.
JAD: That's interesting.
MOLLY: And so he said it's just very well-known that there was fungus growing on things that got burnt, fungus probably just growing 'cause it's wet and damp and why not?
JAD: So there's mold and mushrooms everywhere.
MOLLY: There's also dead bodies. There's, like, things decomposing.
JAD: Which fungus like.
MOLLY: They love, I've heard at parties.
JAD: [laughs] So it looks like you have a couple of shrew-like creatures walking around. You've got some alligators. But you've got a crapload of fungus.
MOLLY: And you've got a crapload of fungus.
ARTURO CASADEVALL: Fungus, yeah.
MOLLY: Is it funj-eye? Funj-eye? Fun guy?
ARTURO CASADEVALL: [laughs]
MOLLY: Is he a fun guy, or is he the funj-eye? Probably funj-eye.
ARTURO CASADEVALL: [laughs] I would say, whatever you like.
MOLLY: No, probably whatever you tell me.
ARTURO CASADEVALL: No, seriously.
MOLLY: Okay.
ARTURO CASADEVALL: Some people pronounce it fun guy, and some people pronounce fun guy.
MOLLY: Okay.
ARTURO CASADEVALL: ...Or funj-eye.
MOLLY: Anyways, whatever you call it, if you are an animal, a reptile or a mammal, fungi can be deadly.
ARTURO CASADEVALL: That's right.
MOLLY: And while reptiles could skip meals and make a bunch of babies, when it came to fending off fungi, we had an advantage.
ARTURO CASADEVALL: We have two pillars to protect us. One of them is that we have advanced immunity.
MOLLY: The immune system is obviously, like, the kung fu fighter. It really takes up, like, the weight of keeping something out.
ARTURO CASADEVALL: But the other thing that we have that frogs don't have and that trees don't have and that insects don't have is that we're really hot relative to the environment. We're warm. We're warm blooded.
MOLLY: Mammals actually use some of their energy to keep their bodies warm. So if you think about us, it could be really cold outside, it could be really hot outside, but we stay at a steady, basically, 98.6. Now, if you're fungi, you actually like it kind of cold.
ARTURO CASADEVALL: They do very well until about 30 degrees.
MOLLY: Like, 86 degrees Fahrenheit.
ARTURO CASADEVALL: Right.
MOLLY: Any hotter than that...
ARTURO CASADEVALL: It could - it denature them irreversibly.
MOLLY: Their proteins start to fall apart. The cells start to melt. And so if a post-apocalyptic fungi got into a post-apocalyptic very warm mammal, it would die.
ARTURO CASADEVALL: These high temperature creates, you know, a heat barrier. And this heat barrier means that the majority of fungal species out there cannot grow or replicate inside your body because you're too warm.
MOLLY: Our heat keeps the fungus out.
ARTURO CASADEVALL: You got it.
MOLLY: If you are a reptile, you're coldblooded. You don't have a way to keep yourself, like, steady and warm. You have to go look for ways to become warm. You know, have you ever seen lizards lie on rocks, you know, where they're just, like, out in the sun, soaking up the heat?
JAD: Sure.
MOLLY: So that will warm their bodies up. But also—and I never knew this—it also will clear, like, fungus from their body.
JAD: Oh.
MOLLY: So if they're sick, because it warms them up so much, that warmth attacks the fungus.
JAD: Do they not do fevers?
MOLLY: They don't - they can't do fevers.
JAD: Oh, wow!
MOLLY: So their way of getting as hot as possible is doing that sun skate thing.
JAD: Oh, [bleep]!
MOLLY: I know! So he was saying that if you're a reptile and you get a fungus, but there's no sun to warm yourself in because the apocalypse has just happened...
JAD: Right - kicked up the dust, blocked out the sun, nuclear winter.
MOLLY: Mm-hmm. So you die because you can't withhold the fungus. But if you're a mammal, a fungus comes, your body temperature naturally kills it. And so, suddenly, his theory goes...
JAD: Interesting.
MOLLY: ... you have mammals filling the hole and really flourishing in a way they never did before because fungus helped them do the mammalian explosion.
ARTURO CASADEVALL: Right, because we went through this fungal filter, and therefore, we are not...
MOLLY: A fungal filter.
ARTURO CASADEVALL: A fungal filter at the end of the Cretaceous.
JAD: Wow!
MOLLY: Now, it gets even weirder because then Arturo decided he wanted to find out, if you are warm blooded...
ARTURO CASADEVALL: What was the optimal temperature by which you get the most protection against the fungi, and yet you don't have to eat all the time? And...
MOLLY: What is the optimal temperature to keep us from eating all the time but still give us defense? The reason we eat three meals a day is to stay warm and functioning. If we were less warm, we could eat less.
JAD: Oh, so it's like, how little can we eat and still be protected against fungus and...
MOLLY: Yes.
JAD: ... stuff?
ARTURO CASADEVALL: That's correct. And what Aviv did...
MOLLY: And so what Arturo did was he got together with this mathematical biologist, Aviv Bergman, and first, they just gathered some numbers.
ARTURO CASADEVALL: What is the temperature susceptibility of fungi?
MOLLY: Like, most fungi don't like it above 86 degrees Fahrenheit.
ARTURO CASADEVALL: And then he looked at the well-known formulas for calorie use. And then he asked the question, if you put these two formulas together, what is the best temperature that keeps out most fungi but doesn't require you to have to eat all the time?
MOLLY: They basically crunched a number that had to do with, like, how many calories you need a day and, like, just, like, the energy that would take of eating and then keeping out pathogens.
ARTURO CASADEVALL: And what he found was that our temperature...
MOLLY: 98.6.
ARTURO CASADEVALL: ...Is that temperature that best balances protection against the fungi versus the need to eat food.
JAD: Whoa!
MOLLY: Bing, bing, bing!
ARTURO CASADEVALL: We were amazed and tickled by it, and so...
JAD: He's saying the reason our bodies are precisely 98.6 degrees is because of fungus? Like, they shaped us to be that?
MOLLY: My heart wants to say yes, but to caveat, he did say it could be totally correlational.
ARTURO CASADEVALL: Right.
MOLLY: Obviously, he's not been able to take the temperature of any of our ancient ancestors. But, you know, it is a very interesting idea that part of being a mammal is about being good at fending off fungi—unless part of that equation changes, which it will after the break.
JAD: This is Radiolab. I'm Jad Abumrad.
MOLLY: I'm Molly Webster.
JAD: Okay. Where we left off, you told us the startling fact that our bodies may have chosen 98.6 degrees to fend off fungus. But then you said, somewhat ominously, that is, unless the equation changes, which it will.
MOLLY: Yeah. So this brings us - some might say finally - back to our medical mystery, which is that Arturo wonders what if, in light of this dino-mammal-fungus detente, this thing that seems new, Candida auris, has actually been here the whole time? So say these fungi typically live outdoors in soil and on rocks. And they live in a place that's, like, you know, normally 75 degrees. It's...
JAD: Hawaii.
MOLLY: You want - OK.
JAD: Let's say Hawaii 'cause they're big into mushrooms there.
MOLLY: OK. Their ideal temperature is 77 degrees. And if they go above that, they start to feel a little queasy, really start to fade, and it's a struggle.
JAD: All right.
MOLLY: OK. So one day, it's 81 degrees. And, like, the fungus are like, oh, [bleep], this is hot.
ARTURO CASADEVALL: All fungi have the capacity to tolerate short burst of heat, but...
MOLLY: But what if the 81 degrees lasts for many days, not just one?
ARTURO CASADEVALL: A heat challenge.
MOLLY: In that case, most of the fungus would die. But the more 81-degree days there are, the greater the chances that in the Russian roulette of evolution, one day, you would get a fungus who's like, you know what? I think I feel pretty OK. And the reason that fungus probably feels that way is because it has, like, a mutation of some sort.
ARTURO CASADEVALL: That give it the capacity to survive the heat.
MOLLY: Maybe it can even fight a little harder.
ARTURO CASADEVALL: Turning on some of the defense mechanisms like heat shock proteins.
MOLLY: However it does it, this one fungus lives.
ARTURO CASADEVALL: And then it creates a copy of itself.
MOLLY: And then that fungus has fungus babies.
ARTURO CASADEVALL: ...What is called a bud.
MOLLY: And then that bud has buds.
ARTURO CASADEVALL: So the original cell may make 50 copies of itself before it basically runs out of juice to make anymore. But those 50...
MOLLY: And so suddenly, you have a whole batch of fungus that survive at 81 degrees.
ARTURO CASADEVALL: Yeah.
JAD: Okay.
ARTURO CASADEVALL: And then after that, you take the survivors, and you expose them to 90 degrees.
MOLLY: Let them sweat it out, and then, boom, you got a whole batch at 90 degrees.
ARTURO CASADEVALL: You got it.
MOLLY: And you can just keep bumping this up degree by degree.
ARTURO CASADEVALL: Exactly.
MOLLY: A string of 91-degree days, 92-degree days, 93-degree days, 94-degree days.
ARTURO CASADEVALL: Ninety-five degrees.
MOLLY: 96 degrees, 97 degrees, 98 degrees and, ultimately, 98.6 degrees.
ARTURO CASADEVALL: Now you have the capacity to survive inside the body of a human.
MOLLY: It reminds me of water. Like, if you're water, and you go from 34 to 33, you're still water, and 33 to 32, you're still water, but there's this seemingly insignificant threshold between 32 to 31 that, when you cross it, you become ice. And it is this almost minute transition that Arturo thinks happened with Candida auris.
ARTURO CASADEVALL: That it was out there living in the environment, and it gradually adapted to be able to grow at higher temperature and it - and when it did that, it acquired the capacity then to cause disease in people. Essentially, its adaptation defeated our heat defenses.
JAD: Wow!
MOLLY: Yeah, yeah.
JAD: So fungus are being trained by the rising temperatures, and they're adapting along with those rising temperatures.
ARTURO CASADEVALL: You got it.
MOLLY: And then, suddenly, it's not that far from, like, you know, that fungus in a soil getting caught on somebody's shoe, who walks it into a town that then goes into a hospital.
ARTURO CASADEVALL: Into an IV line. It can get into a wound, and then it can colonize patients.
JAD: Huh! That would explain why Candida happened in all those places simultaneously. It was always in those places being tracked in on boots into hospitals, but only now it gets tracked in with this new ability to live in us?
MOLLY: Yes.
JAD: Wow!
[NEWS CLIP: Japan is suffering its hottest day on record. A city...]
MOLLY: And this is an interesting thing. Like, all of a sudden, it made me think about all the headlines you see around the world..
[NEWS CLIP: Even in India, it's rarely been this hot.]
MOLLY: ...About, like...
[NEWS CLIP: The country has been experiencing a deadly heat wave with dry air far hotter than the human body.]
MOLLY: It's the 10th straight day above 105 degrees in New - in Delhi.
[NEWS CLIP: All across the west...]
MOLLY: You know, or it's like...
[NEWS CLIP: ...It was another day of oppressive heat.]
MOLLY: Idaho's having the hottest August on record.
[NEWS CLIP: Funerals were underway in Karachi on Friday for some of the victims of the scorching heat wave.]
ARTURO CASADEVALL: You know, many people say, when you tell them about this, but how can that be? You know, they say that the average warmth, it may be one degree centigrade.
[NEWS CLIP: This is a so-called cooling station in Las Vegas.]
ARTURO CASADEVALL: I say that's not the right way to think about it. The right way to think about it is to imagine...
[NEWS CLIP: Triple-digit temperatures.]
ARTURO CASADEVALL: ...The number of really hot days because each hot day is a hoop you got to jump through.
MOLLY: And then just one last dash of interesting in looking at all this, like, fungus temperature stuff - just as the fungus are learning to jump through our hoops, it turns out we are actually making it easier for them.
JAD: What do you mean?
MOLLY: So there was actually - in looking at all this, like, fungus temperature stuff, there was this paper recently that was talking about how the human body temperature has been declining. It's been steadily declining for decades at a rate of, like, 0.05 degrees Fahrenheit per decade.
JAD: Really?
MOLLY: Yeah.
JAD: So we're not 98.6 anymore. What are we?
MOLLY: They think it's actually more around, like, 97.5. But in fact...
JAD: Interesting!
MOLLY: ...What they're - do you get that a lot when you measure your kids?
JAD: Yeah. I'm always like, oh, you're not - you're colder.
MOLLY: The one thing that the researchers were talking about, though, in the declining is that they looked at Western records. But, you know, they say - well, they did a small study on people in Pakistan, and they were more around 98.6. And the researchers were talking about how - essentially, how hard your body has to work to stay healthy, and consequently, the health care system that you're in is what is, like, affecting the temperature decline. So I don't think they think it's, like, worldwide. I think it's a - it's, like, a developed-country Western kind of thing.
JAD: I see. So in countries where there's more advanced health care, you're going to see internal body temp start to lower.
MOLLY: Basically, yeah. So essentially, in sum, there is, you know, this head-to-head between fungus and us, and it is a very fine line going from being insignificant to, you know, king or queen of the castle.
ARTURO CASADEVALL: Many organisms that you recover from the environment can only grow at environmental temperatures. But some of them have - it's a whole range of temperature susceptibilities - or temperature resistance is a better way - an easier way to put it. And some of them happen to—their maximum happens to be just below your temperatures. And these are the ones that we worry about because many of them may have the capacity to cause disease, but they cannot do it because they cannot survive the higher temperatures.
MOLLY: Wait. What are the other ones that are just below my 98.6?
ARTURO CASADEVALL: Well, there are probably—I don't want to be alarmist, but there are probably in the hundreds of thousands or even millions.
MOLLY: [laughs]
ARTURO CASADEVALL: I don't ...
MOLLY: I mean, I don't want to be alarmist either, but now I want to know. What's, like, marching at my heels? Yeah.
ARTURO CASADEVALL: Right.
MOLLY: Wow. That's just so weird. Like, out of all the things that climate change can do to me, I was not thinking about, like, it's warming up microbes on the sidewalk, and they're like, "Oh, finally I can crawl into it a human!"
ARTURO CASADEVALL: [laughs]
MOLLY: And this is the moment we've been waiting for for millions of years.
ARTURO CASADEVALL: It's some image, yeah.
MOLLY: Yeah.
JAD: Wow. Molly, thank you, I guess, for just giving me one more thing to have nightmares about.
MOLLY: Sure. I am always happy to seed your fears.
JAD: [laughs] This story was, of course, reported by Molly Webster, produced by Molly with Bethel Habte. Production help from Tad Davis. Special thanks to Luis Ostrosky. Until next time, I'm Jad Abumrad. Thanks for listening.
[LISTENER: Hi. This is Katie from Boulder, Colorado. Radiolab is created by Jad Abumrad with Robert Krulwich and produced by Soren Wheeler. Dylan Keefe is our director of sound design. Suzie Lechtenberg is our executive producer. Our staff includes: Simon Adler, Jeremy Bloom, Becca Bressler, Rachael Cusick, David Gebel, Bethel Habte, Tracie Hunte, Matt Kielty, Tobin Low, Annie McEwen, Latif Nasser, Sarah Qari, Arianne Wack, Pat Walters and Molly Webster, with help from Shima Oliaee, Sarah Sandbach and Russell Gragg. Our fact-checker is Michelle Harris.]
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