Bite Club

00:00:34

Dr. Kaylee Byers: You are listening to Nice Genes!, the podcast that’s totally bug eyes for science, brought to you by Genome British Columbia. I’m Dr. Kaylee Byers, your host. More on that later, and metaphorical bug net gathering what’s swarming in genomics.

There are a lot of ways humans can get sick from the air to fluids, and sometimes we can get a bad bite.

 

00:01:01

Clip 1: Malaria has been causing untold human suffering for millennia. The parasitic infection is spread by mosquitoes.

 

00:01:09

Clip 2: Anywhere there are ticks, there are concerns about Lyme disease. There has been a steady increase in reported cases of Lyme disease across Canada.

 

00:01:17

Clip 3:  Researchers say the kissing bug disease is now endemic in the United States and not getting the attention it needs.

 

00:01:25

Dr. Kaylee Byers: Some of the most serious and difficult to control diseases in the world, malaria, Lyme disease, dengue, Zika, don’t spread on their own. They hitch a ride through what we call vectors. Those are living carriers like mosquitoes, ticks, and other insects or arachnids that ferry pathogens from one host to another.

Each year, these vector-borne diseases are responsible for more than 700, 000 deaths worldwide. And with climate change, that number could grow. It’s the perfect crime ring, the pathogen, the vector, and us, the unsuspecting hosts. So today, we are putting this whole partnership under investigation. What makes a vector so effective at spreading disease? What makes a good host? And how is genomics helping us trace disease transmission over time, from ancient DNA to modern outbreaks?

 

00:02:20

Field recording: (foreign language)

 

00:02:22

Field recording: (foreign language)

 

00:02:24

Dr. Kaylee Byers: This scratchy tape comes from research carried out years back. A young girl leads the way through her home pointing out where bugs, called kissing bugs, are hiding, an insect that wooed our guest into the field of ecology.

 

00:02:37

Dr. Gonzalo Vazquez-Prokopec: My name is Gonzalo Vazquez-Prokopec. I’m a professor in the Department of Environmental Sciences at Emory University in Atlanta, Georgia.

 

00:02:44

Dr. Kaylee Byers: When Dr. Vazquez-Prokopec looks at disease-transmitting insects, he doesn’t just see a pesky nuisance. He sees a complex system at work.

 

00:02:55

Dr. Gonzalo Vazquez-Prokopec: My area of expertise, I group it within what I call vector biology and control. Because my job is to really understand the complexity of bugs, but use that information, that evidence, to improve tactics, approaches to prevent the diseases they transmit.

 

00:03:10

Dr. Kaylee Byers: How did you end up doing this particular area of research?

 

00:03:13

Dr. Gonzalo Vazquez-Prokopec: My training is in ecology. I’m from Argentina, and at university there I took an ecology class and I got fascinated by the complexity of nature, how species interact. But it all came down from going to the field.

My first research was on kissing bugs, which are like the size of a roach, and they feed on your blood, which is pretty disgusting. And I couldn’t stop thinking about all what goes to that bug and the parasite inside that bug that makes people in a way vulnerable to get sick.

 

00:03:45

Sarge: All right, kissing bug. The name might sound sweet, but we know your MO. Step up and say the line you’ve been given.

 

00:03:54

Dr. Kaylee Byers:  Likely story.

So kissing bugs, I mean, it sounds like a very romantic bug, but like you say, they’re there feeding on our blood. Why did these bugs interest you and why are they just interesting in general?

 

00:04:07

Dr. Gonzalo Vazquez-Prokopec: Yeah, it’s the kiss of death, I guess, because of what they transmit. But I still remember the first time I actually was in the lab, I got one bite from those bugs because when they bite you, you don’t feel it. And the reason why is because they have evolved to develop anticoagulants, but also anesthetics that make, in this case, humans not to feel their piercing. And that fascinated me.

 

00:04:28

Dr. Kaylee Byers: Kissing bugs may sound harmless, but their blood sucking insects that feed at night, often near the mouth or eyes. The real danger, they can spread Chagas disease, a potentially life-threatening illness that damages the heart and digestive system caused by tiny parasites transmitted in their bite.

And they might actually be the culprit for the death of a very well-known biologist. Is it true that Charles Darwin might have died from a kissing bug-associated illness?

 

00:04:57

Dr. Gonzalo Vazquez-Prokopec: Yes, there’s conflicting evidence, but there’s enough evidence to support that because that same reaction I had of the bug biting me has the same reaction that Darwin described in his Beagle notes when he was in Argentina, actually, where I’m from.

Also, the description of his illness and his chronic tiredness and some stomach problems have made many scholars arrive to the conclusion that Chagas is one of the most likely outcomes. It’s not confirmed, but it really fits the picture because he was spending time in the most endemic areas, describing the bugs in the places he stayed. And of course, not knowing that the bugs were infected, there is a plausible explanation on that link.

 

00:05:40

Dr. Kaylee Byers: Poor Darwin, bitten by the kiss of death, maybe, and the bug behind it, the kissing bug, that’s the vector in this deadly love triangle. So, let’s break it down. When it comes to disease spread, who plays what role? First, like we said, is the vector.

 

00:05:57

Dr. Gonzalo Vazquez-Prokopec: A vector is a conduit for a pathogen, a virus, a parasite, they cannot live outside an insect. And the insect is the intermediary between one human or another human. And that’s what we call vector-borne diseases.

 

00:06:12

Dr. Kaylee Byers: But don’t get it twisted. Not every insect is a vector.

 

00:06:15

Dr. Gonzalo Vazquez-Prokopec: For an insect to be a vector, it has to be what we call competent. And competent means that it has to have the ability to not only feed on blood, but has co-evolved with a pathogen to basically either reproduce inside the body or sometimes go through the body into specific organs like the salivary glands. And as they do that, get transmitted into the person. So just because an insect feeds on blood, it doesn’t make it a vector. And competency is the key component of that equation.

 

00:06:47

Dr. Kaylee Byers: So, only the bugs matched up with the virus are competent enough to spread it. And the unlucky recipient in this relationship? That’s the host, could be humans or other animals. But even with a competent vector and a suitable host, there’s still one more ingredient.

 

00:07:05

Dr. Gonzalo Vazquez-Prokopec: Now for a vector-borne disease, we need something else because those two are not in isolation. We need an environment, and the environment is the place in which vectors and hosts enter into contact,

 

00:07:17

Dr. Kaylee Byers: And just to keep things interesting, scientists also have a term for a specific kind of host.

 

00:07:23

Dr. Gonzalo Vazquez-Prokopec: Now a slight separation between host and reservoir, which is another term sometimes scientists use, is that sometimes people get sick, so they get the pathogen in their body and their hosts because they host the parasite inside their body. But in some cases those people cannot pass the pathogen to the mosquito, they cannot close the loop, and we call those dead-end hosts. So, then we have this term to define those hosts that are the ones that are basically maintaining the cycle because the pathogen can go from one host to another one, and the reservoir is the one that basically is maintaining the pathogen in nature and persisting in nature.

 

00:08:00

Dr. Kaylee Byers: So, we’ve got all these different terms for thinking of these different organisms. What makes an organism a really good vector of disease? So, you mentioned it has to be competent. Are there other factors that make it a good vector of disease?

 

00:08:14

Dr. Gonzalo Vazquez-Prokopec: So, what makes a good vector is a combination of factors. And let’s picture vectors of human disease. The ideal vector is one that not only would feed on blood but would do it very frequently. Because the more frequently they bite, the more likely they are to inject a virus or a parasite into somebody else’s body.

And also depending on the pathogen, when you’re looking at pathogens like dengue, dengue or Zika, those are very problematic. They’re actually increasing exponentially all over the world. And what makes dengue such a big problem is that the mosquito that transmits dengue, the scientific name is called Aedes aegypti.

 

00:08:52

Sarge: Number two, mosquito, I’ve been itching to talk to you. Step forward and repeat the phrase you’ve been given.

 

00:08:57

Dr. Kaylee Byers: I am not going to lie, Sarge, never learned to speak mosquito.

 

00:09:04

Dr. Gonzalo Vazquez-Prokopec: It’s what we consider the most efficient vector of disease because it has a couple components. One of them is that they feed every day and a half. Second, what Aedes aegypti does, it feeds a bit on some person and then flies and feeds on another person. And by doing that, they increase the chances of the pathogen to be transmitted.

And the third one is that those mosquitoes are basically highly adapted to urban areas. So, it is really what we call the roach of the mosquito. So because of those components, not all vectors are made equal. And some of those traits of frequency of feeding as well as ability for them to have the virus and reproduce the virus in their body, those are among the top components that actually would make them strongly successful in their quest, in their goal.

 

00:09:49

Dr. Kaylee Byers: And that actually makes me think of my least favorite critter, which is the bedbug. And bedbugs you would think could potentially be good vectors for things. They take little blood meals, they could feed on multiple people, but they carry a different bacteria that can make us sick but to our knowledge, yet they’re not doing that.

 

00:10:05

Dr. Gonzalo Vazquez-Prokopec: You’re right. Yeah, and that’s a great analogy for that example.

 

00:10:09

Sarge: Number three, bedbug, step forward, actually, back in line for now.

 

00:10:14

Dr. Kaylee Byers: So, what makes a good host then? You mentioned dead-end hosts, so not great hosts for passing on the disease, but what would make a good host?

 

00:10:23

Dr. Gonzalo Vazquez-Prokopec: That’s the other side of the equation. Since COVID, the public has heard about the term super-spreader, so we can take the same analogy of what makes a really good host and generally a host would be not the one that’s going to get the sickest. Because generally individuals that perish very quickly after infection would only contribute a small fraction of the pathogen.

But the most effective reservoirs, as we call them, will be those who actually can hold the infection either chronically or for a long period of time. Because in that case, they provide the pathogen more chances of passing into another vector and then from then to another host. That is what we look at when we look at these complex vector-borne diseases is that the puzzle is composed by all these components. And we have found, and research I’ve done describes human behavior, human mobility is really important.

And I’ll give you an example, picture your life. We’re sometimes boring. We wake up, we go to work, we go to the store, maybe we go visit a friend and we go home. That’s our activity space.

What we have found is that the more complex that activity space, the more locations people go, but even the more random locations they visit, the more chances they will get infected or they would infect mosquitoes in them. So, for some pathogens like dengue that only survives between mosquitoes but in human, and human basically passing it to mosquitoes, human mobility is what really makes a good host. And the more mobile, more exposed to bites, the more likely you are to be a super-spreader.

 

00:11:53

Dr. Kaylee Byers: Dengue, which is also known as break bone fever, is one textbook case of this relationship, a perfect crowded urban environment, reliable hosts that can move around a lot in tight spaces and the blood sucking, double dipping mosquitoes that keep the whole thing flowing. As far as disease spread goes, it’s a perfect storm. But pathogens are opportunists and when the setup isn’t so perfect, they’ll find new ways to spread. Sometimes that might even mean rewriting their genetic playbook.

I love origin stories for why people got into the fields that they did. Mine involves sitting in a parasitology class and going through the symptoms of gastrointestinal parasites and realizing I had all of them.

 

00:12:38

Dr. Pooja Swali: Oh, wow.

 

00:12:39

Dr. Kaylee Byers: And I was like, “Wow, I love parasites.”

 

00:12:41

Dr. Pooja Swali: Everyone’s got a story.

 

00:12:41

Dr. Kaylee Byers:  Everyone’s got their origin story.

And to figure out how these pathogens pull off some of these tricks, sometimes we’ve got to dig into their case files going way, way back in time.

 

00:12:52

Dr. Pooja Swali: I am Pooja Swali. I am a research fellow at the University College of London, and I specialize mostly in ancient DNA and ancient pathogens.

 

00:13:02

Dr. Kaylee Byers: Dr. Pooja Swali’s work recently made headlines for studying a very specific pathogen, one you may have never even heard of. So, one of the pathogens that you work on is this Borrelia recurrentis. And can you tell us what that is?

 

00:13:18

Dr. Pooja Swali: Yes. So, Borrelia recurrentis is in the relapsing fever family. So, there’s quite a few Borrelia bacteria, and it’s a bacteria that causes a relapsing fever where someone would get sick and then they would be fine and the bacteria manages to persist inside the individual, and they will relapse and get a fever again. It’s well-known cousin is Lyme disease. So, I think Lyme disease is quite a popular and well known pathogen.

 

00:13:44

Dr. Kaylee Byers: Borrelia burgdorferi, is that the…

 

00:13:47

Dr. Pooja Swali: Yeah, I was just trying to see if I can pronounce it. So, Lyme disease is quite a well-known pathogen, but relapsing fever, it’s not even classified on the neglected tropical diseases. And it’s normally, especially louse-borne relapsing fever, is found in East Africa and often in areas of poor sanitation and overcrowding and is believed to have epidemic potential and it’s largely understudied.

 

00:14:13

Dr. Kaylee Byers: Why is this something that has been understudied and why do you think it hasn’t gotten much attention?

 

00:14:17

Dr. Pooja Swali: So, Borrelia recurrentis up until I think in the last 10 years, it’s been quite hard to culture because it’s very specific to the human host. And now you think if a pathogen is very constricted to a human host and infects humans, it’s one to watch, because we’re very human-centric.

 

00:14:35

Dr. Kaylee Byers: Very.

 

00:14:35

Dr. Pooja Swali: But for this one, if it’s left untreated, the mortality rate is estimated to be between 30 and 40%. But if it is treated, then it’s five to 10%. But whether treatment can be accessible is a whole other question because of the regions it tends to affect. I think it’s got mostly to do with where it’s impacting populations is why it’s so understudied and why it’s quite hard to diagnose.

Only a handful of genomes have actually been sequenced. So, in the modern data set there were two main studies and both of these data sets have been from East Africa and this has generated all the data, which is about eight Borrelia recurrentis genomes, which isn’t a lot. When you’re looking at something like COVID, which is under thousands, millions of genomes, to have eight and trying to understand how this pathogen has evolved, its distribution, what it looks like, how it infects people, it’s really lacking in diversity for us to be able to answer these questions.

 

00:15:39

Dr. Kaylee Byers: So, you’re studying the past of this pathogen and the critters that it lives in. Can you tell folks who aren’t familiar with what is ancient DNA?

 

00:15:48

Dr. Pooja Swali: So, ancient DNA is the study of historical genomes. Normally, it can be from museum specimens, so we say historical genomes also count as ancient sometimes, but you go all the way back really, really far back. In fact, a paper has just been published on a bacterial genome that’s 1. 1 million years old from a mammoth.

 

00:16:07

Dr. Kaylee Byers: Wow.

 

00:16:08

Dr. Pooja Swali: So, we’re pushing this timescale of how far back we can go and what we can get data from. And it doesn’t even have to come from the bone of an individual, it can come from the soil as well. But long and short is that it’s just old DNA that’s very, very short, fragmented, and it’s typically known as damaged DNA.

 

00:16:29

Dr. Kaylee Byers: With only a handful of ancient genomes to work from, Pooja’s research faces some serious challenges. But have no fear, scarce and damaged evidence is no match for a DNA detective. Coming up, a classic case of genetic carjacking, the very curious discovery Pooja’s research uncovered about the evolution of this relapsing fever and what the findings could mean for the future of disease spread.

You are listening to Nice Genes!, a podcast all about the fascinating world of genomics and the evolving science behind it, brought to you by Genome British Columbia. I’m your host, Dr. Kaylee Byers. And if you like Nice Genes, hit follow on Apple or wherever you get your shows and leave us a review, like this episode, share it with your best bug whose itching for genomic stories.

When Pooja and her team dug into the ancient DNA samples of Borrelia recurrentis, the bacteria behind relapsing fever, they uncovered something unexpected about its past.

 

00:17:30

Dr. Pooja Swali: So, we see this in three other bacteria that go from their tick-borne ancestors to louse-borne. So, their transmission dynamics have completely changed.

 

00:17:40

Dr. Kaylee Byers: Thousands of years ago, this pathogen made a dramatic leap. It switched hosts from ticks to lice.

 

00:17:47

Sarge: Tick, step forward. Louse, step forward. Did you see the look they just gave each other?

 

00:17:53

Dr. Kaylee Byers: Oh yeah, those two are in cahoots for sure.

So, in the study you sequenced some of the oldest Borrelia recurrentis genomes ever recovered. And what did those ancient genomes tell you about how that bacteria has evolved?

 

00:18:07

Dr. Pooja Swali: It was a lot more complicated than we thought. So, the frustrating thing about this tick-to-louse transition is that there is no one gene that can tell you this was transmitted by a tick or a louse. So, that was out of the question to look for. So, we had to start looking at other things.

We looked at the oldest of our samples, we managed to get four, and the oldest of it was about 2, 300 years old. And we looked at the genome decay over time and what we saw was that it wasn’t as simple as the genome just decays. We saw that it’s actually quite dynamic, and even though it’s decaying, it’s also gaining genes.

Now, the majority of the decay had happened by 2300. So, the most parsimonious explanation is that it probably was louse borne at this point. But something with ancient DNA is that you can never say for sure. Science has never been answered in one paper, it just opens more questions.

So, what we think has happened is that it’s decayed and it’s an ongoing process, and we’re actually able to capture some of that decay happening between 2300 to our youngest genome, which is about 700, 600 BP, before present.

But what was interesting is that where a gene was lost, because you assume it’s not useful for the pathogen, a homologous gene that has a very similar function was gained straight away in a complete different part of the genome. So, there’s things happening where the pathogen is shedding but also gaining, which is super cool.

 

00:19:38

Dr. Kaylee Byers: So, what is it in the DNA or about this pathogen’s history that we know that it was once in a tick, but now it’s in a louse.

 

00:19:45

Dr. Pooja Swali: We’re basing it on of the diverse Borrelia species, all of them are in a tick. And then we have this one pathogen where all of its ancestors are again tick borne and then it’s louse borne. It’s the most simple explanation as to why we’ve landed on this assumption.

 

00:20:03

Dr. Kaylee Byers: I love to imagine Borrelia recurrentis bartering with its tick and louse accomplices, swapping genes like shady characters making secret deals. But what really a-louses my curiosity is why. Well, right around when this sneaky vector switch happened, there was some other pretty significant changes going on.

 

00:20:22

Dr. Pooja Swali: So, about 6, 000 to 4,000 years ago is what is known as the Late Neolithic/ Early Bronze Age. And during this time, we start to see the spread of secondary animal products such as wool. And we know that lice eggs tend to favor wool. The rough material of the wool might be better for harboring the eggs.

So, it could have been an opportunistic moment for the pathogen to be spread through human lice. So, we see the spread of wool, which coincides with the emergence of Borrelia recurrentis. Now, correlation is not causation. A lot of things is happening at this time, but it is these secondary animal products that do make us question, maybe this is a lot more recent, maybe it isn’t the living with animals that are causing these spillover events. Maybe it’s a lot more complex. And the changes in human history like movement of wool can help us understand the intricacies of pathogen and vector dynamics.

 

00:21:21

Dr. Kaylee Byers: While it’s intriguing to think of the emergence of wool use coinciding with relapsing fever switching from ticks to lice, it doesn’t mean one caused the other. Like Pooja says, it’s correlation versus causation.

It’d be like saying climate change is getting worse and there’s more Keanu Reeves movies coming out, but that doesn’t mean that Keanu Reeves movies are the driving cause of climate change.

 

00:21:42

Keanu: No way.

 

00:21:44

Dr. Kaylee Byers:  We love Keanu. He would never. But looking at these smaller human driven changes, like the spreading of wool, helps us start to untangle how shifts in human behavior influence the way that diseases evolve. Thinking more broadly about when we see this change from tick to louse, what does that teach us about that relationship between humans and animals and the vectors that live on them?

 

00:22:07

Dr. Pooja Swali: Yeah, it definitely shows this, but I guess this was always known, that it’s so much more complicated. But what’s interesting is more the timescale for me is that I would assume a lot of pathogens have quite an established vector transmission dynamic. I wouldn’t have thought it would’ve changed so recently in time. It’s quite a large change and it’s quite distinct. It’s not a different species of tick, it’s a different genus.

 

00:22:33

Dr. Kaylee Byers: We’re talking about something that has eight legs versus six, right? This is a big shift.

 

00:22:38

Dr. Pooja Swali: Yeah. It’s not gone to a louse that feeds on multiple hosts, it’s gone to one that feeds specifically on human hosts. So, it is a very curious situation.

 

00:22:49

Dr. Kaylee Byers: What might you say about how that past could teach us about how we might manage infectious disease into the future?

 

00:22:56

Dr. Pooja Swali: We look at disease control and a lot of the time we target the vector population or the reservoir populations, but it does show how dynamic these pathogens are. So targeting a certain population, a certain vector, it goes to show that the pathogen is quite dynamic. It can change into other vectors, it can change into other hosts.

 

00:23:16

Dr. Kaylee Byers: Pooja, thank you so much for coming on. It was such a delight to chat with you and thank you for sharing your work with us.

 

00:23:21

Dr. Pooja Swali: Thank you so much for having me.

 

00:23:23

Dr. Kaylee Byers: While Borrelia recurrentis may have abandoned the tick as its main vessel, ticks are still thriving, second only to mosquitoes when it comes to spreading disease.

 

00:23:33

Dr. Gonzalo Vazquez-Prokopec: My joke, my silly comment is that I have yet to find somebody who can tell me I love ticks or I love mosquitoes. In a divided world, you can have different political, ideological perspectives. We all get unified to the idea that we all hate mosquitoes. We all hate ticks.

Ticks are one of those species that are really problematic. Because not only they’re small, the ones that transmit pathogens out of the size of a poppy seed, but also when they’re in the environment, they are in very high numbers. So when we go on a hike, you can encounter what we call a tick bomb, which are these massive numbers of ticks crawling on you. They’re waiting for a host to basically jump in.

 

00:24:14

Dr. Kaylee Byers: Nightmare fuel, but even though no one likes a tick, studying them is crucial.

 

00:24:20

Dr. Gonzalo Vazquez-Prokopec: So, our lab is studying now tick-borne viruses and the one we study is called the lone star tick, and it’s a native tick of this part of North America, the South. And there are two viruses we study. One is called Heartland virus and the other one is called Bourbon virus.

Very few people know about them. But what happens is the clear example of why temperature and climate change are also changing the map of vector-borne diseases, because as wintertime gets warmer in northern latitudes, the tick is able to survive the wintertime. And when you look at the progression, the tick has made it all the way to Canada. Now, that tick as it moves north is also moving pathogens with it. And our work is really trying to understand emerging vector-borne diseases from the perspective of those pathogens that are not coming from another part of the world. They’re native of the environment, but as humans get more in contact with the ticks or as ticks moving to other areas, people might be more prone to actually getting sick from them.

And particularly, we’re interested in viruses because ticks transmit many things, but viruses are the ones that are really hard to study and understand. And we want to know what can we get of these viruses before they potentially become a problem.

 

00:25:32

Dr. Kaylee Byers: In that study. Do you use genomics at all?

 

00:25:34

Dr. Gonzalo Vazquez-Prokopec: Because these viruses are very poorly known, we have to use all the possible tools in our toolbox. And yes, we do use genomics and we use it for multiple reasons. One of them is to understand the population structure. Our team has sequenced more than half of all the genomes of Heartland virus that exist in the world, and there are not that many.

But because we have very few samples, we’re able to reconstruct not only the history of when or since when the virus has been in the tick, and our analysis shows that it appears that the virus and the tick have been together since the time the tick was here. So, they’ve been together for at least 500 years, which is when we think Amblyomma americanum, the tick we studied, the lone star, made it into Georgia.

 

00:26:22

Dr. Kaylee Byers: One other thing I want to ask you about is urbanization and climate change and changing environments and what our disease landscape looks like right now for vector-borne disease versus what it might look like say 50 years from now.

 

00:26:31

Dr. Gonzalo Vazquez-Prokopec: I would argue that sometimes we spend too much time only talking about climate. And what happens with vector-borne diseases is that climate is only one component of the equation. And when you look at northern and southern latitudes, the vectors are expanding like into Europe or Canada. That’s a very clear association with climate variability or in this case warming in those locations.

But there are other components. In the endemic areas, we are also seeing increases of transmission not because of climate. We’re seeing it because vectors, and particularly urban vectors, are expanding or even growing in numbers. And I’ll give you an example.

So, Saharan Africa has been dealing with malaria since the time of man. Malaria is the biggest killer, the biggest pathogen in terms of human deaths in our world and even in our human history. Its malaria. Humans have done tremendous great work preventing and reducing the burden of malaria in Africa.

But Africa is seeing a new problem. Since 2017, 2016, Africa has been invaded by a new mosquito called Anopheles stephensi, which is the mosquito that transmits malaria in India. Now, what makes this a very problematic issue is that Anopheles stephensi is an urban mosquito and vector of malaria. Malaria is primarily a rural problem, so areas that were malaria-free since history now are becoming malaria-prone.

And the reason why that mosquito is jumping into Africa primarily is because of construction. The construction boom in Africa is fueling the ability of this mosquito to actually expand and even establish a new territories. And with that, there is a big concern that malaria is not going to go down, actually it’s going to go up again. Right now, we’re seeing the early stages of that invasion. But as scientists, we’re trying to look ahead and we can see that a changing environment, not only climatically but also environmentally, could lead to this instances.

And the final example is Lyme disease. Lyme has expanded exponentially in North America, primarily because of land use change. And as we build for houses, town homes, and as we constrain forest patches to become more isolated and fragmented, wildlife doesn’t have where to go. And those fragments of forest now have deer and small rodents, which are the key reservoirs for Lyme. When we go hiking into those areas, we get more exposed to Lyme.

So, this is another environmental change that is really driven by land use. And I think the reason why I make this argument is not because climate is not important, is that there are many other changes that we are making to our environment that mosquitoes and ticks are really exploiting and they know it. They know and they’re basically taking advantage of that. And we have to look at it at a broad scale in terms of what is driving this rapid increase.

 

00:29:22

Dr. Kaylee Byers: And that leads nicely into my final question for you, which is why is it so important to study these vectors?

 

00:29:28

Dr. Gonzalo Vazquez-Prokopec: Well, the burn of vector-borne diseases as we talked, is increasing for the ones we know, but also for the ones we don’t know that are emerging. As many of these pathogens continue expanding, it creates a need for action. And that need for action is that we cannot assume anymore that a place with mosquitoes is a safe place.

So, actions that we have to take are actions to prevent illness, and because some of them can become serious, they’re also actions to educate the community about the importance of being alert. So, my main message for everybody is it takes a village. It takes everyone from the different sectors of the community to deal with the problem of vector-borne diseases.

It’s as much as a problem in your household as it is for a country trying to create policy on vector control. It all starts with learning and understanding what are we dealing with, what’s the biology. I like the title of the podcast, Nice Genes, what are those genes doing that make us sick? But also what can we do as citizens, as scientists, and as a community to prevent that from continue happening.

 

00:30:32

Dr. Kaylee Byers: Dr. Vazquez-Prokopec, this was really interesting and a personal pleasure for me. Thank you so much for taking the time to come on the show.

 

00:30:38

Dr. Gonzalo Vazquez-Prokopec: Thank you.

 

00:30:39

Dr. Kaylee Byers: We’ve covered a lot today, diseases and the clever ways they spread, from Chagas to dengue, malaria to Lyme, even relapsing fever. They all rely on a middle critter, shuttling pathogens from host to host.

These pathogens are crafty too. Gaining and losing genes, sometimes even swapping the vectors they use. Genomics helps us untangle how pathogens move, adapt and evolve, and how we can fight back as the world turns.

 

00:31:07

Sarge: All right, everyone, listen up. Each of you vectors is guilty as something. Time to own up.

 

00:31:12

Dr. Kaylee Byers: Let’s start with you, kissing bug.

 

00:31:14

Sarge: Possible death of Charles Darwin, breaking and entering with deadly intent.

 

00:31:18

Dr. Kaylee Byers: Mosquito.

 

00:31:19

Sarge: Serial stabbings and accessory to severe disease spread.

 

00:31:23

Dr. Kaylee Byers: Bed bug.

 

00:31:25

Sarge: Right, disturbing the peace.

 

00:31:27

Dr. Kaylee Byers: Louse.

 

00:31:28

Sarge: Petty theft that turned deadly.

 

00:31:30

Dr. Kaylee Byers: And finally, ticks.

 

00:31:32

Sarge: Accessory to identity theft in the relapsing fever case and running a multi-disease smuggling ring, Lyme, Bourbon virus, Heartland virus. You’re a repeat offender.

 

00:31:42

Dr. Kaylee Byers:  I mean, some of these are really creative crimes, but the evidence doesn’t lie.

 

00:31:47

Sarge: Well, Byers, in the pathogen justice system, no one gets off easy.

 

00:31:54

Dr. Kaylee Byers: Our guests for today were Dr. Pooja Swali, a research fellow working on pathogen genomics in the Van Dorp Group, and Dr. Gonzalo Vazquez-Prokopec, ecologist, epidemiologist, and professor at Emory University.

You’ve been listening to Nice Genes!, a podcast brought to you by Genome British Columbia. If you like this episode, go back and check out some of our previous ones wherever you listen from, share it with your friends and leave us a review. You can also DM the show on social media by going to @GenomeBC.

We talked a lot about bugs today. And lucky for you, we’ve got another bug coming up, the stomach bug.

 

00:32:30

Dr. Lawrence Goodridge: We get to China and these students, they do everything I tell them not to do. I, on the other hand, use all of my food safety knowledge I’ve accumulated to that point, and guess who it was who got sick?

 

00:32:42

Dr. Kaylee Byers: Join us next time as we get a gut check on the microbiome. From food safety to mental health, your gut microbiome could be your most powerful line of defense. Thanks for listening, detectives.