Climate Change and the Rise and Spread of Pathogens

The climate isn’t just warming—it’s reorganizing the rules of biology. We explore how rising temperatures, deforestation, wildfire smoke, and thawing permafrost are reshaping the risk landscape for malaria parasites, heat-trained fungi, spillover-prone viruses, and resilient bacteria. From Kenyan highlands that became friendlier to Anopheles mosquitoes, to urban heat islands that may condition fungi to tolerate our body temperature, to the sobering lesson of Siberia’s anthrax outbreak after unusual warmth, we connect data points to the lived reality of health systems on the front lines.

We dive into malaria’s life cycle and why vector capacity accelerates in warmer, deforested microclimates. We examine fungal threats, including how wildfire smoke can disperse spores, and why limited antifungal options raise the stakes. On viruses, we unpack Ebola’s reservoir ecology, the role of habitat loss and food insecurity in human–animal interfaces, and how language and stigma can undermine outbreak response. Finally, we look at bacterial risks within permafrost feedback loops and across water and food systems, where floods, droughts, and soil microbiome shifts threaten safety and yields.

Throughout, we keep solutions in focus: protecting forests and wetlands, cutting fossil fuels and air pollution, building climate-smart surveillance and diagnostics, and communicating with dignity so communities participate in prevention. Climate action is infection prevention—and it starts now. If this conversation sparked new questions or ideas, subscribe, share with a friend, and leave a review to help more people find the show. What solutions can you enact in your life to face the rising threat?

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Transcript

Welcome Back And Life Updates

SPEAKER_00 0:07

This is a podcast about one health. The idea that the health of humans, animals, plants, and the environment that we all share are intrinsically linked.

SPEAKER_06 0:15

Coming to you from the University of Texas Medical Branch and the Galveston National Laboratory.

SPEAKER_00 0:19

This is Infectious Science, where enthusiasm for science is contagious.

SPEAKER_03 0:29

Hello, welcome back to the infectious science podcast. We are now completely online. We are calling in from different places. We haven't seen each other in a while. Christina, I haven't seen you in like months. How are you?

SPEAKER_02 0:44

It's been a really long time.

SPEAKER_03 0:46

Where are you? How are you doing? How's med school treating you after you just completely disappeared? What's going on in your life?

SPEAKER_02 0:53

So third year started basically. We took our first licensing test, step one, and then moved on to third year. And third year is typically just like the most rigorous year of med school. So you're working full time, but you're also studying full time, and it's just it's a lot after a while. So just hanging in there. But that's why I've disappeared off the face of the earth this year. I do apologize, but it's so good to be back. It's so good to see you guys too, and to get to record this and also just learn from you guys and have fun and catch up. So I'm excited to be here.

SPEAKER_03 1:30

I thought people always say that med school gets easier the further you get through the coursework, no?

SPEAKER_02 1:37

I would say like first two years, I would say that's consistent just because you develop study habits that really get you through the rest of the pre-clinical years. But then clinical years, third year is definitely the hardest year, and I would say that's typically the hardest year of the entire medical school curriculum, just because of the balance between working and studying.

SPEAKER_03 2:00

Yeah. And your studio looks a little studioed. Your uh desk looks a little different. Are you calling in from Galveston? Uh where are you currently?

SPEAKER_02 2:08

I am. I'm calling in from my home, which is in League City. But I always just say Galveston because I don't think a lot of people know where League City is. Yeah. But yeah, I'm still local, but I know Miss Camille is not. She got up and left. Where are you at, girl?

SPEAKER_01 2:25

I am in upstate New York, which is beautiful. It's autumn right now. We're recording this towards the end of October, and it's absolutely gorgeous. The leaves are falling, and every time I step outside, I just inhale the smell of falling leaves. It's so good. Yeah, I'm doing good. And I'm loving that I have access to apple orchards and like apple cider again because I miss those things in Texas.

SPEAKER_02 2:47

That sounds so wholesome as a Texanite. I could not imagine that. So Texanite.

SPEAKER_01 2:54

You've got to explore the north. You've got to explore the north. It's so gorgeous. And I love being in the mountains again. I miss the mountains when I was in Texas. I could never go hiking in Texas. I could only go like walking, at least where I lived in Texas, because it was just like so flat.

SPEAKER_05 3:10

That's something that's been so important about the state. I used to go hiking all the time when I was back in Reno in Nevada because we were so close to the Sierra Nevada and Lake Tahoe, all those hiking trails around there. Around here, if you get an elevation gain of more than 17 feet, I'll call it good.

SPEAKER_03 3:31

That is true.

SPEAKER_01 3:32

Yeah, the most elevation you gain in Galveston is like going up a set of stairs. That's it.

SPEAKER_03 3:39

Very fair. Agree. Very true. Alex, were you in Galveston right now?

SPEAKER_05 3:45

Yes, I'm on Island. So yeah, just in ensconced in my apartment at the moment. And I must say, I I think I've had a chance to see you a little more in recent weeks, considering now that I've been collaborating with Dr. Benta, which I've really enjoyed. So I ended up moving in a bit of a different direction after my qualifying exams. And so now I'm working with Dr. Caitlin Cotter and Dr. Courtney Wolsey. And I am proud to say that Dr. Benta is going to be on my committee indeed. So I've got to be able to do that.

SPEAKER_04 4:16

Oh exciting. Oh, I know.

SPEAKER_03 4:21

Have you nailed on your topic yet? Can you talk about it at this point?

SPEAKER_05 4:25

At this point, we're settling on the topic. I still need to work on getting my candidates sleep proposal all in order, but I think that the broad scope of it at this point is going to be a project that's uh looking at the intersection between loss of virus disease and pregnancy, and looking at that from an epidemiological perspective, right? And also uh looking at that using actual patient serum samples from Nigeria and looking at some of the biomarkers that are associated with severe disease in the pregnant individuals. Yeah, but still a work in progress.

SPEAKER_03 4:58

Yeah, cool. All right. So today's topic is one of my favorites. It's climate change. Can we say this word out loud? Do you think we're gonna get like immediately No?

SPEAKER_01 5:13

I it's I it is peppered throughout my notes for this episode. So we start us off with yeah, absolutely. So I think it's really important to begin this episode by defining the anthropocene. This is a period of time that we're currently living in. So we're living in the Anthropocene right now, and it's characterized by humans being the most influential species on our planet. And so it's really widely accepted that we, and by we I mean humanity, have really deeply impacted our planet, right? So, particularly in the past 60 years. In the course of natural history, humanity's actions are pretty unnatural in how we've affected the world that we live in. And our current lifestyles really rely on things like natural resource extraction, and that disrupts ecosystems. We've seen unprecedented carbon dioxide emissions, global warming, acidification of our oceans, and habitat destruction, as well as massive extinctions. And what we really want to focus on today in this episode, against this really urgent change is needed backdrop, is the impact of the Anthropocene on multiple classes of pathogens. So we're gonna talk about fungi, we're gonna talk about viruses, bacteria, parasites. But just super quickly before we jump into that, as many of them are a really big reader and post-PHD, I am like reading even more because I actually have like more brain space for reading. And I recently came across this erasure poem of a news piece that was documenting a funeral that was held for a glacier in Iceland. And this is gonna be like relevant later because I do talk a lot about permafrost. But what's really interesting is that there was a plaque dedicated during this funeral for the glacier, and on it was inscribed this. So this is a direct quote: a letter to the future. Okay is the first Icelandic glacier to lose its status as a glacier. In the next 200 years, all our glaciers are expected to follow the same path. This monument is to acknowledge that we know what is happening and what needs to be done. Only you know if we did it. I find that super poignant in the current moment because the undercurrent to all the concerns we're going to discuss in this episode is that we really do know what environmental problems we have created. And for the most part, we really do know how to resolve them. And so I was actually recently reading a Natural History Museum article, and it really outlines what steps do we have that we've agreed on to like move towards a better future. And it's things like stopping the mining of fossil fuels and transitioning to reliance on sustainable alternatives. That's something we urgently need. So is reducing emission of air pollutants, right? And those things can go hand in hand. We also really concur that we need to protect at-risk ecosystems. Those are things like wetlands and coral reefs. And we know that things like eating less meat reduces environmental strain. And I say that as a kid who grew up on a beef farm. So I don't know if anyone has questions about that. And also, we know that shifting economic goals and reducing inequality and stabilizing the world's population will also help us move towards a better future. So I just want to note before we jump into everything in this episode, these aren't easy changes to make, and so a lot of them have not been made, because the systems, there aren't really systems designed to support people during these shifts that we know need to be made so that no one gets really unequitable or punishing treatment as the changes we need to avert disaster are being made. And so I just want to start off with the anthropocene, and we know what needs to be done because we know these are the solutions we need to rapidly enact. And there just really isn't enough being done in like a corporate or a government or necessarily an internationally collaborative scale, which is often where change is most needed. So then individual change can sort of gather weight within a system that's already designed to reinforce it. So that's the current crisis.

SPEAKER_03 9:07

And maybe if an if I can jump in and just make an announcement to our listeners as well, right? This is a very complex topic. And if you've listened to the previous episodes, we always take the lens of focusing on pathogens and not necessarily only from the perspective of pathogens, but this topic climate change is obviously much broader than that, right? There's an influence on plants, on humans. It's just so broad. I think we would have to have a whole season just to cover these topics. Now I want to uh do a quick plug here, I guess. I took a class, an online class that Yale offers. It's called Health and Climate. And it's an online course that you take, it's over a few months, and I took so much away from that. And I think probably the key message for me is just how complex and how interconnected everything is, and from heat stress to losing water and so on. So I just wanted to preface this episode by saying we're taking a snapshot of certain aspects, but obviously this whole topic is much, much broader.

SPEAKER_01 10:13

Oh, yeah, absolutely. I for sure echo that. And everything we're talking about today, these are things that come up and we can just scratch the surface of. But there's so much more to this topic, and it can be hard to engage with, right? Because it can feel very hopeless. But I guess I wanted to preface it the way that I did because we do know what needs to be done, and there are actions we can take. And so I think that's just always an important thing to me to set up when you talk about climate change, is that we do know what needs to be done, and there are actions we can take, and then get into like, all right, so what problems are we facing? So then we can think about how do we move forward and why does it matter that we do move forward. Alex, do you want to jump in?

Malaria Basics And Climate Links

SPEAKER_05 10:49

Absolutely, yeah. Well, to that end, so I think I'll start out by talking a bit about the genus of parasite responsible for causing malaria and how your human-driven climate change has ultimately impacted malaria prevalence and incidence. So, just to give at first just a brief introduction about malaria, so it's obviously caused by an infection with parasites of the genus Plasmodium and the spread through the bites of mosquitoes of the genus Anophiles. And so there are 249 million cases annually and about 608,000 deaths annually per the World Health Organization as of 2022. The vast majority of these were concentrated in sub-Saharan Africa and were as a result of infection with Plasmodium falciparum, which is the most virulent of the Plasmodium pathogens in general. And so, to give a basic overview in terms of how malaria's pathogenicity works exactly, there are various stages of life of the malarial parasite that it goes through. And those stages can have differing impacts on both the human immune system as well as they're intrinsically tied to a replication within the Anopheles mosquitoes themselves.

SPEAKER_02 11:55

You gave such a great overview of basically plasmodium and malaria and how it infects people and how it, I guess, evolves within the body. So just to synthesize what you said, malaria is, and correct me if I'm wrong, okay? I want to understand. But basically, malaria is a parasitic infection that is spread by the anophiles mosquito. And so the mosquito bites, and it basically gives the parasites to the victim of the bite, and these parasites go to the liver, right? And that's where they mature, and then from the liver, they go and they spread throughout the body or and infect red blood cells. And so that's why malaria is really dangerous, is because not only are red blood cells necessary for carrying oxygen throughout the body, but these parasites essentially cause the death of the red blood cells. And so with fewer red blood cells in the body, there's less oxygen being sent throughout the body, and there's also this inflammatory reaction within the body that can cause a lot of other detrimental side effects. Is that correct?

SPEAKER_05 13:01

Absolutely, yes. That's a perfect summary.

SPEAKER_02 13:03

Okay, cool. I just wanted to make sure, yeah.

SPEAKER_03 13:06

Alex, why did you pick malaria, just that of interest as a disease? Is it because of its global impact, or is it was it just a disease of interest for you in general, or why did you pick that as the topic?

SPEAKER_05 13:17

A bit of both, a bit of both. Because it was something that when I was an undergrad, my research had been characterizing the interactions of this crystalline toxin produced by Bacillus therogensis, known as Cryfor B, which had these insecticidal interactions with the caterin receptor inside of the mid-gut of Anopheles gambiae, which is the principal vector for plasmodium falciparum, which is the most lethal of the malarial agents. And so I've always been interested in malaria for some time after going and doing some of that research in undergrad, but the scope of my research, of course, never really touched the parasite itself. So I figured it'd be fun to uh learn some more and talk about it here. But also, it's just, yeah, just something that absolutely, as you mentioned, the global health significance of it is just something that's worth noting. And so I figured may as well call attention to it and for that too.

SPEAKER_02 14:09

Alex, before I interrupted you, sorry, you were getting towards the whole topic of global warming and climate change and how malaria is potentially becoming more prevalent because of the change that we're seeing within our global climate, is that correct?

SPEAKER_05 14:23

Absolutely, yes. There have been significant issues when it comes to, yeah, deforestation and forest degradation being these really big drivers of climate change. They're ultimately estimated to constitute about 12 to 20 percent of global greenhouse gas emissions annually. And because you know, as you're releasing and removing these carbon sinks rather from the global ecosystem, right, you're releasing CO2 into the atmosphere, which can be deeply problematic. And a number of these changes, of course, are linked to changes in land use, right? Clearance of forest lands for subsistence agriculture, as well as for industrial farming. And so these can help to, in some ways, resolve perhaps issues of local food insecurity that in and of themselves are driven by climate change indirectly or may contribute to global markets, right? But the issue though with deforestation is that it has a significant impact on also then warming these environments that enable anophthalese mosquitoes to then better thrive, right? So there was this 2006 study that found that in these deforested areas in the Kenyan Highlands, that these areas were about 1.2 degrees Celsius warmer in the dry season and 0.7 degrees Celsius warmer in the wet season. And that doesn't sound like much, but these mosquitoes were found to have considerable increases then in their net reproductive rate and in their populational intrinsic growth rate in these areas, which thus enabled an increase overall in the vectorial capacity of these mosquitoes to go about being vectors of the malarial parasites themselves, thus increasing the likelihood of transmission to humans, right? Because you have more mosquitoes and they reproduce at a higher rate, you're just going to have a greater propensity for potential mosquito-human interactions that could lead to malarial infection, which is particularly problematic.

Deforestation, Warming, And Vector Shifts

SPEAKER_01 16:09

Yeah, if I could jump in, speaking of this kind of interaction between humans and vector species, I don't know if you found anything on this, but something that just popped into my head as you're talking about this, because it's really interesting, is not only may we be changing how land is being used or the microclimates that are available, but also if it's really hot out, people might be going outside to do work in times where it's cooler parts of the day, like morning or evening, where they might be more likely to come in contact with mosquitoes. So I don't necessarily know that I did not dive into malaria for this episode, but this idea that, you know, as things get hotter, not only do microclimates change and not only do land use change, but also people are trying to adapt to that to do the work that they need to do, right? If they're outside doing agricultural work in a prime time when they might be bitten by mosquitoes, they might be more likely to be exposed to malaria.

SPEAKER_05 16:56

No, that's a that's an excellent point. And Camille also, I think, raised a very good point there in terms of just, yeah, changes in human behavior when it comes to these warming environments and then potentially participating in some of these outdoor activities at points in the day when they are more likely to be bitten by these anophily mosquitoes is definitely a significant factor as well. Absolutely. So that's a that's a great point. So as a result of the warming climate writ large as well, what we've also seen is that some of these areas that have historically been epicenters of valarial incidents, right? Some of these equatorial regions that are historically hot and humid and in a position to support a high anophaly's population, is that we're seeing a number of these mosquitoes instead move towards more hospitable environments as those regions grow too hot to support necessarily their reproduction. And so what we've seen is over the past 30 years, increases in the incidence of malaria throughout regions in which it had been relatively low or even non-existent, such as in the Ethiopian islands. And some of that has to do with geopolitical and conflict issues when it comes to especially Ethiopia in particular, with issues over the past few years in particular, but but also you know, largely have to do with these climate changes, and that's uh a deep problem, absolutely.

SPEAKER_03 18:15

And the listeners are interested in human conflict, uh war and conflict, go back to a couple episodes ago when we talked about the pathogens and war, so go back to that episode. But Alex, my question for you is so you were talking about the expansion of the mosquitoes into new regions, northwards and probably southwards as well. But what we see with the tick-borne diseases is yes, there's an expansion northwards and southwards into new areas because now they become habitable for ticks. But we also see that certain areas that used to be good areas now change their climate so much that they are not suitable anymore for ticks. So it's not just a continuous expansion into all areas, but almost like a contraction, right? It goes up into a certain area, but like certain other areas will the disease or the vector will disappear. Did you read anything about that with malaria?

SPEAKER_05 19:13

Yes, indeed. So that's exactly what has followed as well, that there are reductions in and projected to be reductions in incidence of malaria in some of these equatorial regions in which it has grown too hot to necessarily go and support that same high population of Anopheles mosquitoes. And so, yes, that's a great point, absolutely, because yeah, it's definitely not a continuous expansion, but it'll contract in some of those historical hotspots as well. So it sounded like you've got some stuff for us too, Camille, no?

SPEAKER_01 19:46

Yeah, absolutely. But I don't want to cut Dennis off and talking about ticks. If you have anything more to add on ticks, now is the thing.

Human Behavior, Ticks, And Vector Movement

SPEAKER_03 19:54

This is your moment. My moment to shine, yes. Yeah, I think you know what the other parts, I think there's certain themes that are the same. You do see an expansion of ticks into new areas, quite a bit, actually. But what the difference is the way mosquitoes and ticks travel. Like mosquitoes can fly, they have a range of hundreds of meters, and ticks can only crawl so far. They often use animals, cows, for example, imagine like pastoralists, where you have ticks on a cow and they're moving to new areas. So they use almost other animals, wild animals, birds, and so on, as tick taxis, basically, where they get to new spaces. So the transport into new areas is slightly different than some of mosquitoes, and also the establishment of ticks into new areas is also very different than mosquito species. But I think that the tendency, generally speaking, are the same. So similar picture with slight differences. Does that answer your question, Camille?

SPEAKER_01 21:00

Yeah, yeah, absolutely. I just wanted to give you a moment to talk about ticks. We know how much you want to know.

SPEAKER_03 21:06

And I never get to talk about ticks here.

SPEAKER_02 21:08

I do like a special tick episode for Dennis. Oh no, it's gonna be 99.

SPEAKER_01 21:13

And you can just educate the rest of us. I found a tick on me like the other day, like on my jeans, and I immediately thought of you when I saw this tick. It was like crawling up the knee of my jeans, and I was immediately like, oh, I was like, Dennis would think that's cool.

SPEAKER_03 21:31

Is this a good thing or a bad thing that you immediately thought of me?

Fungal Threats In A Warming World

SPEAKER_01 21:38

It's I don't know. Probably now. I feel like our listeners probably think of me whenever they hear like the fungus among us based on the episode that we did. And I am returning to fungus for this episode. So I'm gonna talk about fungi. So if you like take it, you just get yeah, you just get associated with the things that you're like really intellectually curious and excited about. So I think let's talk about fungi. Fungi and climate change is just such a cool topic, if you ask me. A former professor of mine once brought up how in the past fungal pathogens really haven't been major health concerns for humans, the way like viral and bacterial pathogens have been. And she really spoke about how this was due to the fact that the majority of, although certainly not all, fungi don't really thrive at the temperature the typical human body is at because it's really too warm for them. You can probably see where I'm going with this because we're talking about global warming. So fungi that do infect humans usually only thrive pretty superficially, right? Like they're subcutaneous, they're on our skin, something like that. Because your internal body temperature really just isn't like habitable for them. So if someone's gonna get a fungal infection, it's gonna be something like athlete's foot or ringworm, it's on the skin. And similar to we've talked about something like bacterial pathogens previously that also don't like super warm temperatures. We've talked about like on lepre and things like that ends up surviving on like the tips of the fingers or the nose first or something where it's a little cooler. And fungi are like that in a way that we've been very fortunate that a lot of fungi don't happily exist at our body temperature. But that can easily change. And that's actually something that's being tracked right now in real time, which I think is really wild. In the journal of PLOS Pathogens, this is a direct quote because I found it really interesting. For the vast majority of fungal species, the capacity to grow at elevated temperatures limits their ability to infect and establish in mammals. However, fungi can be trained to evolve thermodolerance. End quote. So global warming is Christina, your eyes just got so big. It's really, it's really, it's something out of almost like out of a horror movie, right? Like it's just global warming is absolutely giving fungal species basically the training wheels on the road to infect more humans. And I think we should all be concerned about that. I think about this probably more often than the normal average human does, but I just think people should know about it because it's wildly interesting. The planet is essentially fevered, right, with global warming. Like we've given it a fever. And the freedom we have previously really enjoyed from the threat of fungal pathogens might be coming to an end because of that. And I was reading this paper called Climate Change and the Emergence of Fungal Pathogens. And so this is a quote from that. So gradual adaptation to increasing temperature caused by climate change could lead to an increase of organisms that can cause disease. That makes sense, right? It tracks. We're increasing the temperature of the entire planet. So things need to adapt to live at those temperatures. And so warming the planet means that these fungal pathogens are going to be adapting to survive and thrive at higher temperatures, which are temperatures that are far closer to a human's body temperature than we probably want to be comfortable with. And some scientists have also proceeded to warn that climate change can increase the geographic range of pathogenic species or their vectors, leading to the emergence of diseases in areas where they've previously not been reported. So, Alex, you just talked about that with mosquitoes, but the same also holds true for fungi because of the way we've warmed up the planet, but also other sort of wild weather events that are happening. What's concerning about this is that fungi, there's currently no vaccines for fungal pathogens. There's some under development, but there's none approved. And we have pretty limited antifungal agents. And what's also interesting when you consider a fungal pathogen versus something like a virus or a bacterium is that fungi can live sapotrophically. So they can produce large quantities of infectious spores, and they don't require host-to-host contact to establish infection. So they're really uniquely capable. This is a quote fungi seem to be uniquely capable of causing complete host extinction, which is like not a great idea to think about. But it's something that we should be concerned about and thoughtful of. Because we have, I think, in some cases and in a lot of academic journals, there's these scientists that are sort of ringing the alarm bells about global warming in fungi. But I'm not really sure that's necessarily hit like the broader media of people thinking about this. Because beyond the development of thermal tolerance, one of these articles has this sort of wake-up call that a rapid increase in human fungal disease under climate change can be caused by shifting precipitation patterns. And it can also be caused by other ecological disturbances. And in some cases, there's even projections of like how might this actually cause these shifts and what might this look like. And increased precipitation, which we're seeing a lot of places and higher temperatures, as well as droughts. So all things we're seeing right now could more than double the endemic range of a fungal pathogen called cidiodomycosis, which is the soil fungi. It's colloquially known as valley fever when it's an infection. So that could double by 2100, the year 2100. So causing, so that's an increase in cases by 50%. So these are things that we should be thinking about, but that's a projection. And so what I want to talk about is one kind of example to round this out is that what's happening do so we know what's happening. Yeah.

SPEAKER_03 26:58

Camille, can I interrupt you? I just want to tell you that next time I see a fungus, next time I see a fungus on something, I'm gonna think of you.

SPEAKER_01 27:06

Oh, thank you. I appreciate that. That makes my heart happy. I'm honored.

SPEAKER_03 27:13

Let's go and like fungi and think of it. I'll be in fear that this fungus will just completely take over the world. And yeah, but I do uh disagree with you though. Look at the TV show The Last of Us, which is focused on uh uh fungus. So I I think there's growing awareness that that fungi could be could be a threat, right? So do you think that's just really a circle of a few scientists that talk about this?

SPEAKER_01 27:42

So I I think that's true, but I guess what I say what I mean, I don't think it's hit mainstream media in like a realistic way, right? It's almost like zombies, right? Yeah, has it like hit the broader spectrum of like media? Oh, look what could happen. But like it's again because it's I feel like The Last of Us really falls within that zombie pop cultural phenomenon. People are like, oh, that couldn't happen. And I'm like, oh, I don't think we're gonna become like zombies. You don't need to worry about becoming a clicker. I do think you need to be mindful of how these pathogens might be spreading because of human actions, which to me is far scarier than like any sort of like horror show.

SPEAKER_02 28:17

And it's really interesting, Camille, because like with the pattern that we see with you would think, right, that the warmer the planet is getting, and these fungus are not, I guess, evolved to survive in these warmer climates, you would think that they would, if anything, be dying off. But the fact that they have this ability to adapt, that just shows how like how not I guess evolutionized, but also how persistent and just like the survivability of these fungus. It's it's beyond what we even really consider when we think of fungus. And it's beyond what we understand, probably.

SPEAKER_01 28:55

Yeah, yeah, totally. And I'm gonna talk more too uh in when I talk about bacteria, I'm gonna talk about permafrost pathogens and how little we know. It's fascinating, anyways. Go ahead, man.

SPEAKER_03 29:06

Before you go on, Camille, I just want to ask you the same question that I asked Alex, and it's a question that you probably have no answer. I have no answer, but I'm just curious to ask. So, you know, you talked about like that that the fungi are mostly like infecting the skin, but they're also systemic infection. You mentioned belly fever, right? There's candida albicans and thrush and so on. And often when we have these systemic infections, typically, rule of thumb, the body is pretty good at avoiding fungal systemic infections unless there's some immunocompromised state or a co infection or maybe a poly trauma that reduces the immune system, correct? So now going back to the heat stress that humans will face in certain areas, and maybe even animals, right? Like we need to focus on humans. Could you imagine that this heat stress that also leads to maybe like immunocompromised states could also increase the susceptibility to those infections.

Smoke, Spores, And Urban Heat Islands

SPEAKER_01 30:06

Yeah, that's a really interesting thought question. And it's not something that I ran into when I was looking into this episode, but I think more than just heat though, I worry about other things that are occurring that we don't even think about. An example that I didn't even think about. So I said at the beginning of this episode, I'm up in upstate New York, right? At the beginning of the summer, we had smoke from the Canadian wildfires, which it's not great. You don't love it when you're outside and it's just being in a bonfire. But they did a study that in California hospitals between 2014 and 2018, research found that admissions for coccidodomycosis increase by 20% in the month following exposure to wildfire smoke because it can disperse fungal spores. So not even just heat, but these other climate change associated events, something like wildfires, which more and more people are being exposed to and that smoke can carry and can then disperse fungal spores with it. Do I have any idea what kind of fungi are chilling up in Canada? None whatsoever. Was I probably breathing some in with the wildfire smoke? Yeah. But are you saying this is fortunate to be but that's not necessarily the case and you wouldn't even think about it. I know so many people who are exposed to like California wildfire smoke. A really good friend of mine lost her whole house in the wildfire that we had this past summer. And that's utterly insane. And that's not even something people think about. They're just like, oh it's pollution right you're breathing this in I've never heard anyone talk about the fact that you could be inhaling fungal sports and that's going to increase hospital admissions in a system that might already be taxed, right? Because you have people that are coming in that are maybe have other issues. Are they even looking for fungi, right? Is a 20% increase real or is that underreported? Because your first thought probably is rarely fungi in people because again, there's not that many that infect us. But particularly in a system where maybe you've already seen a ton of people because the people are shifting and then there's stress and any other kinds of conditions can flare, you might not be thinking about it. And so I think that that's something I'm thinking about beyond just heat, like wildfires, but also deforestation. Alex mentioned what happens to mosquito populations when they're deforestation. As far back as the 1990s deforestation on Canada's Vancouver Island may have driven outbreaks of cryptocarcosis which is caused by the carcass gatty and it's due to logging releasing fungal spores into the environment and that's wild, right? So this idea that when we start disrupting nature, right, we run up against things that we didn't necessarily expect to find or didn't even think to think about. But back to your point on heat, because it's really interesting. One of the emerging threats which you mentioned it's one people might have heard of and that's candidauris, which is it's commonly associated with hospital outbreaks. It's a type of yeast. And it is actually though the first completely new fungal species hypothesized to have emerged due to climate change. And that is because there was simultaneous unexplained emergence of three types of Candidaoris on three continents so at once. And so that's why it's hypothesized to be because of climate change. So something that people were like oh it's a hospital infection but it's an infection that we all contributed to in many ways.

SPEAKER_03 33:18

Camille sounds like it's not only the last episode for you but also the last episode of this podcast because we all gonna die off Canada.

SPEAKER_01 33:31

I don't mean it like that. I want us to be aware but not like to the point where we're like oh fatalistic of the going to hell in a basket. Again like that's why I preface this episode with the small little like list of hopeful things we can do because it matters, right? But anyways to wrap up the fungal section, the last thing I want to say is that it concerns urban environments, which we haven't touched on yet, but they do matter in regards to what we're talking about with climate change. So urban environments have documented heat island effects which I had never heard of until I was researching this episode. So that means they're several degrees warmer than their surroundings due to factors like buildings and traffic. And so they might be contributing to the very thermodance that we don't want fungi to develop, which I thought was really interesting. So that's what I have on fungi.

SPEAKER_05 34:17

Yes. That's really fascinating especially I just I I just want to say I'm just still stuck on the as somebody who for a long time lived in northern Nevada and was oftentimes downwind of some of those fires in Northern California now I'm just wondering as far as all of the stuff I was exposed to like it might not just be Camille's last podcast it might be mine too at the night that we're going.

SPEAKER_03 34:44

You made it this far so it's all good. But I was thinking about the smoke and stuff like that. Like you Christina you probably would agree that not only does smoke apparently carry fungal spores which is news to me to be honest with you I know that virus particles can float on dust but I didn't know this but uh don't you think that Christina does that also this inhaled smoke also causes damage to your lungs and makes you more susceptible for other infections?

SPEAKER_02 35:11

That's what I was thinking of when Camille was talking about the smoke and everything and then I thought that's where she was going with all of this but yeah she surprised me with the turn she took there. I didn't realize that those colors were carried in the smoke itself. But what I was thinking of was the damage that the smoke does to your lungs inevitably in the future if you're exposed to that chronically if you're exposed to other insults chronically like tobacco smoke or anything like that will break down your lung tissue and result in a sort of not immunocompromised state of the lung but just result in insults to the lung tissue that will make it more susceptible to infection with just pathogens that we don't really think about a lot or pathogens that healthy lung tissue would be able to fight off on its own. So yeah I thought that was really interesting. I do want to say just as a disclaimer if you are a healthy individual and you have healthy lung tissue and you've inhaled spores or something like that for the most part thankfully our body's immune system is incredible and it's able to wall off these infections or it it fights off the infection without us really even knowing. So for our listeners don't be afraid that we're all gonna die but it is really focusing we're worrying about just new increased exposure to these fungal pathogens that we're being exposed to when we really didn't even think about it.

SPEAKER_01 36:35

Yeah absolutely yeah I wonder if it's like a double insult to yeah the smoke is already an insult to the lungs and so maybe you're become more susceptible but then also it's what's in that smoke that's carried right it's almost the perfect storm right like you've become more susceptible because you're probably stressed there's a wildfire near you you also are inhaling that smoke which is potentially quite damaging to the lungs. And then there's also what's contained within that smoke as far as something like fungal spores.

SPEAKER_02 37:03

So yeah. That'd be a really interesting research project to do it's just obviously it would be really hard to do because you have to look at that population in that that moment but to see is that immediate insult of high doses of forest fire smoke and stuff like that combined with the exposure to the spores does that increase your chances even if you were a healthy individual before of uh contracting active infections of these rare fungal diseases is it's really interesting.

SPEAKER_03 37:32

Yeah.

SPEAKER_01 37:33

Christina you mentioned you wanted to also talk about permafrost is that correct I did not want to talk about permafrost yeah I'm gonna talk about permafrost what lurks in the deep yeah but Alex is going to talk to us about viruses first.

Ebola, Reservoirs, And Land Use Change

SPEAKER_05 37:50

Way more fun than fungus I think the permafrost subject frankly is worth it. I hope we can have enough time to have another episode later in the season on it because I was really intrigued by I'm really excited to hear your bacterial segment I'm gonna try to get through my stuff on viruses quickly then um you have to have to eat your vegetables before the dessert I'm here all day yeah my PS always told me that I would do really well as a comedian but only in really niche environments only if I was telling jokes of actual conference like the American Association of immunologist medium like anything outside of that good luck.

SPEAKER_03 38:32

Who said that to you?

SPEAKER_05 38:33

Okay tell us Alex tell us about the viruses about the viruses all right alright just so for this I decided to particularly focus on Ebola and on its links with climate change and so I'm just gonna give a bit of an overview to Ebola virus disease and then I'm going to talk a bit about some of those linkages again similar to what I did on the parasite side. So yeah Ebola virus disease can be caused by several members of the genus Ebola virus which are these negative stranded RNA viruses that are within the family Phyloviridae. Many of these can be transmitted person to person secondarily but these outbreaks typically stem from an initial contact between a human and the animal reservoir for these Ebola viruses. So it's worth noting writ large that members of the Ebola virus genus are endemic to sub-Saharan Africa and the natural reservoirs of these viruses have not been fully confirmed but there are various species of fruit bats, the pteropodidae that have had Ebola virus RNA that have been isolated from them or have displayed zero positivity and their an experimental infection of fruit bats has indicated that infection may persist in those theseptomatically for some time which leads us to believe that then these are the likely reservoirs of this virus. And so either direct contact with infected bats or with their bodily fluids and this is something that comes up with NEPA virus, right? But if you think of a bat that's going and feeds on fruit tree, right? And it might salivate on that piece of fruit it may go and get some of its secretions or excretions onto it and ultimately then you may not know it. It might be picked off later and it might be consumed. That could be a potential exposure pathway along with something that is a big issue and that kind of ties in with some of these climate change issues is that of course the climate change is a significant driver of food insecurity and bushmeat consumption has been something that's been increasing and this could be a potential problem when it comes to an a yolk as well as there are also these secondary reservoirs that can be part of the infectious cycle because other great apes can be infected, right? So these include say gorillas, chimpanzees and other such animals and these similar to us, they end up experiencing significant degrees of mortality as a result of infection but consumption of infected bushmeat of animals that maybe end up secondarily infected also can lead to significant issues as well and could lead to potential infection as well as just direct interaction with some of these bats, right? The 2013 to 2016 Zaybola virus outbreak in West Africa, which was the deadliest and most widespread outbreak on record, right? There were tens of thousands of cases associated with it.

SPEAKER_03 41:16

And that's probably what was said previously like deforestation right like you you said the exposure of humans to those bats, yes bushmeat, but also deforestation so they don't have a place to go and so they probably go more into like human proximity that might be another factor. I remember from back then from that West Africa outbreak that it's also the interconnectedness of people right like that people are so mobile maybe not linked too much to global change but that because the human behavior changes so much and one person can go and cross over to another country very quickly I think those were all things that were not predicted. I think nobody had an idea that an outbreak would be so big but because of all of those confounding factors led to this massive outbreak right absolutely I also would like to jump in super quick.

SPEAKER_01 42:08

Oh yeah um so this is something that I actually I've discussed with I believe Matt Dashu he's one of the the originals of the podcast team and he often joins us at night. Yeah he always seat on the couch and we had this really really fascinating discussion that we don't like bushmeat as a term because it's just meat. And the reason I bring this up is that literally anywhere people are hunting game in the United States, in Africa in Europe in Asia anywhere, you can definitely come in contact with pathogens. A great example of this is semi-recently in the United States there was a hunter out in the Midwest he was butchering a deer obviously you open up the chest cavity of the deer and he got tuberculosis. And so I just want to push back a little on the use of the term it's often used in academic literature but I I don't think we should just because I think it brings in something we talk about a lot in infectious science, right? Is othering, right? It's like when we say wet markets, you probably have an idea of what pops in your head with a wet market, but there's wet markets everywhere in the world, right? There's wet markets a couple hours from my house in New York City, right? I think these are things that I just want us to think more about. And there's so much nuance and there's so much context. And I just want to add that to the conversation when we're thinking about this because there's so much change going on. And I think you bring up a great point on food insecurity right and kind of what I touched on the intro is like there's this sort of push that we have all of these changes that we know need to be made but a lot of times the changes are going to end up with a punishment or an inequity for people that we just haven't moved forward on a global or international scale to be like, hey, by solving inequity, we actually make the world a better safer place for everybody. So that's always something that I want to bring into the conversation too.

SPEAKER_05 43:50

So I just wanted to make that little anecdote if I can absolutely thank you both for that because I was planning on getting to some of those points as well about deforestation that you raised Dr. Benta because yeah that's a critical driver here of some of these reservoir human interactions that could take place. And to your point Camille absolutely as somebody who has just delved through some of this literature at times when it comes to doing the research for an episode that's something that I didn't know that there had been that sort of discussion in the field about that but it makes perfect sense because I think that in many ways the otherization and the stigmatization of some of these behaviors that people engage in as part of their day-to-day lives is deeply problematic when it comes to public health and when it comes to controlling any form of disease, infectious or non-infectious because the fact of the matter is that when you go and you put limitations on or otherwise distinguish these behaviors that people undertake, it can be so detrimental to being able to actually reach those people. I remember seeing a while ago I was writing this paper comparing and contrasting the US and Botswana and their responses to their AIDS epidemics, right? And something that was a key distinguishing factor in many ways between the two was that the US did not have laws on the books that were banning same-sex activity after 2003 with the Supreme Court case of Lawrence v. Texas and in general even prior to that had a more welcoming ecosystem for LGBT folks at least legally than Botswana did. And so oftentimes that led to significant underreporting and we see that even still regardless throughout the rest of the world because of historical inequities when it comes to the LGBT population seeking healthcare but yeah these big gaps when it comes to being able to go and reach out to the men who were having sex with men and and vulnerable groups that were engaging in these behaviors that are just part of human existence, right? But were otherwise for legal and various reasons classified as other and thus stigmatized and thus those people may not have always heard that message. That's a really good point.

Language, Stigma, And Public Health

SPEAKER_01 45:57

Yeah and this is what I love about infectious science. We can always be learning and also this is why I love the field of infectious diseases as an entire field because there is so much nuance and complexity and there's always something to learn there's always something to dive into and there's always a way to find a way to connect with people and to learn from the very human experience of illness and othering and all of these things that come together for all of us in some way throughout our lives. You know, and there's so many different ranges of severity obviously but that this is something that in a way what I love most about infectious disease is how much it connects us, right? And it also shows us where we need more connection because we have fractures. And so I think that's always I feel like what things come back to with infectious science as a podcast but also just as a field for me. So yeah.

SPEAKER_03 46:43

We talked about fungi we talked about viruses and we talked about the vectors not enough about ticks clearly we need to have a separate episode on that yeah we got our own episode for that then we hear you there's there's one thing missing right where are the bacteria the bacteria and the permafrost all right let's dive into it I feel like you all set this up so much.

Permafrost, Bacteria, And Feedback Loops

SPEAKER_01 47:07

And I do have to say this section definitely only scratches the surface of permafrost because you can talk about viruses and the permafrost like you can talk about so many interesting things. So I really do think we should probably dedicate a whole episode to it but I found it so cool that I just had to do a little bit of it for this section of this episode. There is a ton of ways that global warming is impacting bacteria and vice versa, right? And so one really great example of that is our planet's permafrost region. So permafrost is a mix of frozen soil, ice and rock and it lies under about a quarter of the land in the northern hemisphere, which I did not know. That's like a massive amount of land. What's really pretty wild though, that I found out by you know recent episode is that in September of 2025, so very recently, a group of scientists from the University of Colorado found out that if you thaw out permafrost, like you take a sample and you thaw it out, the microbes in it aren't at all past viability and will form colonies that can break down organic matter, which is abundant in the permafrost. It's like a whole graveyard in there of everything that's ever died and been buried in ice. And that releases carbon dioxide and methane which has the potential to form a loop that really exacerbates global warming. So you have the global warming causing thawing right and as it thaws these microbes can then essentially come out of this sort of, I don't really want to call it a deep sleep that's really anthropomorphizing them, but it's a good metaphor, I guess. And then start to break down the organic matter that is already in this layer and that can release more greenhouse gases which warms things up further and so on and so forth. And so you have the potential to have a cycle that ends up being really bad news for us. And also in addition to that something that I feel like a lot of people have pointed out is that we don't necessarily know what we may be thawing out. So there's always the potential it's not zero that we have the potential to thaw out diseases that we don't want to be exposed to. And according to a science article and I say that with science like capital S, like an article in science who's titled Lurking in the deep freeze this is a direct quote. So temperatures in the Arctic are rising twice as fast as the rest of the world. And so that's really wild to think about twice as fast as the rest of the world and there's so much more damage that can be done when the permafrost is thawed out. And we know that at least one epidemic has potentially already been caused by global warming and probably by this sort of cycle of thawing out the permafrost. And so that is in 2016 Siberia had an unusually warm summer and Bacillus anthracis which is better known as anthrax is a bacteria that's found in the soil and it killed 2,649 reindeer and sickened 36 people, killing one 12 year old boy. And so while we can't say for certain that this epidemic was driven by global warming as Siberia has previously experienced outbreaks about a century ago, it's definitely plausible that this epidemic was at least in some way mediated by the rising global temperatures. So it's definitely worth considering that there are things in soil that definitely do make us sick. And if you thaw out soil and then you know animals that are up there that are definitely going to be more exposed to it, there's something like grazing or whatever, or if you'd even think about something like livestock, right? I think that this is something to think about that you know our health has the potential to be impacted in other ways than just exposure to infections. So for example a really huge part of our food supply relies on soil bacteria to aid plant growth. This is something that we have established if you've ever gone through probably some basic biocourses, you probably had to go through this. And a really recent study in Nature Foods pivoting from this permafrost idea was predicting that fossil fuel dependence has the potential to lead to a significant decline in abundance of plant beneficial bacteria on a global scale by the year 2100. And this is really worrying because this change has really the potential to threaten the global food supply. If you suddenly have a decline, a significant decline in plant beneficial bacteria, you're maybe going to have issues with crop growth you're gonna have issues maybe with what you are able to grow doesn't have as much nutrition in it because the plant was struggling. We also have all kinds of other wild weather events that are already influencing where we can grow crops like droughts and we also have things like wildfires, you know, that we've already mentioned so bacteria really matter to us and not only is like the food supply at risk from global warming, but things like clean water are too right according to the WHO if you have extreme climate events like floods and cyclones and droughts all of which we have seen this year in multiple places around the globe, those all impact access to clean water and that can really create ideal environment bacteria like cholera to thrive or things like that. So I think that this is all just to say that there are so many different ways that global warming and severe weather events are really impacting the bacterial species that we might come in contact with whether things are thawing out, whether those things that are thawing out are increasing the cycle and then allowing wild weather events to occur in other places that could affect our access to clean water but also can impact the growth of plant beneficial bacteria. Like it's all so interconnected and it's such a web and there's so much nuance to it. And there's definitely probably a lot of really cool permafrost things that we can dive into in another episode. But this is really the gist of what I wanted to bring up for bacteria. And I think it's just so important as we kind of wrap up this episode to think about how everything we've talked about has some interconnection, right? Because it's not just a domino effect. It's so much more than that that there's basically this entire web and every time we're plucking a string of it, everything else is also moving with it. Yeah.

SPEAKER_02 52:51

Yeah I think that's a beautiful way to summarize it because really we've talked about so much in this one episode. We started talking about fungus and then we went to oh no we started with parasites technically and then we went to fungi and then we went to viruses and bacteria. So yeah that is a really good way to summarize things Camille and just recognize how interconnected everything is which is what we talk about so much in this podcast when it comes down to it.

SPEAKER_01 53:15

Yeah yeah absolutely interconnectivity is I feel like what we always come back to.

SPEAKER_05 53:20

Yeah there's just such a delicate equilibrium when it comes to so many of these factors in the world and how they come and interplay, no? And that's something that I think you summed that up absolutely beautifully Camille this was a great note I think to end the episode on and I hope we get a chance to dig in to more about these permafrost pathogens because they're quite something to behold all right.

unknown 53:41

So um yeah.

SPEAKER_03 53:43

Sorry I miss that part it's just totally cut off.

SPEAKER_01 53:46

That's all right that's all right you'll have to listen to it when it hits the Spotify and Apple Podcasts and all that stuff.

SPEAKER_04 53:53

Yes.

SPEAKER_01 53:54

All right cool thank you everyone so much for joining us for this episode of Infectious Science. We're glad to be here with you and we appreciate you listening. Let us know what you want to hear about. Feel free to reach out to us and until next time stay safe stay healthy think about fungi and how cool they are thinking to contribute to meeting kind of the crisis of our time.

SPEAKER_06 54:20

Yeah totally absolutely I think one of the big key takeaways that we got from this episode is climate change doesn't just affect the future generations it really does affect us in the now and our health and I think that's something that is important to recognize so if this episode taught you anything let it be that yeah thanks for listening to the Infectious science podcast be sure to hit subscribe and visit infectious science.org to join the conversation access the show notes and to sign up for our newsletter and receive our free materials.

SPEAKER_00 54:51

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SPEAKER_06 55:00

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SPEAKER_01 55:09

So we'll see you next time for a new episode and in the meantime stay happy stay healthy stay interested this podcast is sponsored in part by the Institute for collaboration and health an action oriented nonprofit that partners with innovators in science and health working with communities to develop nimble approaches to the world's most challenging health problems