Screwworms

A parasite that eats living flesh sounds like a monster movie plot until you realize it has a scientific name, a documented history, and a very real comeback story. We’re talking about the New World screwworm (Cochliomyia hominivorax), a fly whose larvae infest wounds in humans and animals, driving pain, infection, and massive losses in livestock operations. Through a One Health lens, we trace how this single species ties together ranching economics, wildlife reservoirs, and the fact that diseases do not recognize borders we draw on maps.

We walk through the screwworm life cycle and why it’s so damaging, then unpack the surprisingly elegant control tool that once pushed it back: the sterile insect technique. Because female screwworms mate only once, releasing irradiated sterile males can collapse reproduction without relying on widespread insecticides. We also revisit the history behind “eradication” claims in the United States, the long-running strategy of holding a barrier farther south, and what happens when funding, surveillance, and infrastructure lose priority over time.

From the Florida Keys to Texas and New Mexico, we look at the conditions that help resurgence: underreporting, movement of livestock, and even pet relocation. Finally, we get practical about treatment and prevention, including the realities of manual larva removal, wound care, antibiotics, and what pet owners can do right now to reduce risk.

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Transcript

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One Health Intro And Screwworm Hook

SPEAKER_04 0:09

This is a podcast about OneHe. The idea that the health of humans, animals, plants, and the environment that we all share are intrinsically linked. Coming to you from a team of scientists, physicians, and veterinarians, this is Infectious Science. Where enthusiasm for science is contagious. Alrighty, hello everyone. Welcome back to this episode of Infectious Science. I'm Camille, one of your co-hosts, and I'm joined by Christina and Alex. Hey, so good to be back. All right. We are so excited to get into a very, very cool topic today. Okay, so fun fact: we're gonna be talking about screw worms, right? And they're these parasites that are like totally right out of a horror movie. And they're actually what interested me in infectious science in the first place. When I was 16, the Animal Plant Health Inspection Service, also known as Aethus, they had all these young folks who wanted to be scientists go down to the Virgin Islands, and we got to chat with people who were running the facilities that were irradiating screw worms and keeping them at bay and keeping them from being in the United States at that time. And it was so fascinating. I got to see this big jar of dead hazards of screw worms. I was hooked. And ever since then, I've been full-on fascinated by infectious disease. That's one that I ended up studying in undergrad. And then obviously that's what I did in grad school, but that's how it started. And also when I was at Cornell last year, they have this massive entomology collection. And there's an alum. I was in there for a little tour, and then I bugged the bug guy to be like, Hey, can you show me where the screw worms are? And I made him go through all the catalogs and pull them out. And so I got to see the larva, and like they're so gross and so cool. So we're gonna be chatting about them today. Aren't you jealous? Just too many, yeah. That's really remote. Yes. So I've always been obsessed with screw worms. Always. I think they're the coolest thing. And they're also like really terrible, right? They're really awful. So their scientific name actually translates to man eating spiral shell fly. I don't know, Alex, you want to get into that?

SPEAKER_02 2:05

Yes, absolutely. So originally when they were characterized by the French entomologist Charles Coquerel, when there was a parasitic infestation that ultimately caused the death of hundreds of prisoners on the infamous French penal colony of Devil's Island in French Guyana, he had discovered these larvae that were gnawing on the prisoners, and which is a mildly terrifying taxonomic name to have, certainly. Doesn't undersell it in the least.

SPEAKER_04 2:33

It's very zombie.

SPEAKER_02 2:35

Absolutely. I completely agree with your description, Camille, about it sounds like a parasite out of a horror film. And usually I feel like when I think about taxonomical names, I I don't tend to think of them as always capturing the terrifying essence of these so much.

SPEAKER_04 2:50

As someone who's calling in from Kit Cod, Massachusetts, or in Texas, where there is actually a resurgence of screw worms. So I feel like much more comfortable

Screwworm History And Scary Naming

SPEAKER_04 3:00

talking about this.

SPEAKER_02 3:10

Between Lyme and the Eastern Equine Encephalitis, I think that you got your bases covered, okay? But back to the screw warm, absolutely. Yeah. So yeah, now the current name, the genus ended up changing to Cochleomila hominivorax, which stems from more of a description really of the morphology of the actual larvae itself, from the Greek cochlea, so small with a spiral shell, and Maya, which is a fly, right? Well, perhaps a little less poetic than beautiful nine man-eater. This one is perhaps a little more apt.

SPEAKER_04 3:45

Yes, yeah.

SPEAKER_02 3:46

So it was Simple Island, just also, yeah, for a little more context on it. In addition to being a penal colony, it was famous, for instance, housing Alfred Dreyfus of the Dreyfus affair, of the whole spy scandal that rocked 19th century France in the aftermath of the Franco-Prussian War. It was also the host of a laper colony, and it was also indeed, as I just alluded to, a place where political prisoners were often sent. And the last prisoners went off of the island though in 1953, so it's close now, thankfully. Recently. Indeed. Surprisingly recently. You hear about penal colonies, and I don't know about you, but I tend to think about like Australia and Botany Bay and all of that sort of a thing, right? And it's hard to think about the fact that like it's kind of recent.

SPEAKER_04 4:29

Yeah, I think the C3 is more recent than you would think. Yes. I was pretty startled.

SPEAKER_05 4:35

Absolutely.

SPEAKER_04 4:36

But yeah, it's the first place that screw worms were really classified and identified, as you said, Alex, but they're endemic here, right? So there are old world screw worms, but what we're talking about right now is new world screw worms. They're endemic to Central and South America, which are found throughout the Caribbean, Mexico, and also you can be found very widely in the southern United States. So they've been here a while, right? And they are naturally here. They're endemic, they're just an insect that we have around, and their life cycle is pretty gnarly. So if you are eating dinner or you have a soft stomach, you may want to horse and return because they're about to get into their life cycle. So New World screw worms lay their eggs in open wounds or in places like the nose, the ears, or in belly buttons. And once the larvae hatch, they burrow into the wounds. They literally screw themselves into the flesh and then they consume the living flesh of their host about a week after eating their way through their host. They will fall out onto the ground and they become pupa in the environment, and then they emerge as flies. After emerging, females only mate with one male, and then they can lay up to 3,000 eggs in their brief lifespan. They only live 10 to 30 days, but they can lay up to 3,000 eggs in more wounds. And so you can see how this is very nerve-wracking for people or anyone around animals, that kind of thing. Like the eggs are laid and they're on wounds, or they're in like open orifices, like the nose or something like that, and then they're chewing their way into tissue. And they're pretty spooky looking if you look up images of them. I don't recommend looking up wounds if you have a soft stomach. A lot of them came up without me expecting it when I was searching this. I was like, even as an infectious disease biologist who's done cadaver labs, I was still like, wow, that is really gnarly. They definitely should have a little filter of you might not want to see this. But, anyways, because as I mentioned, they only mate with one male, the females, once they merge, only mate with one male. And this monogamy is really what has allowed us to lower their population in many places because we can irradiate the males, right? So they're exposed to irradiation, and this makes them sterile. And then you can release a bunch of them, they'll go mate with the wild females that are in the population in the area they've been released in, and then those females don't produce fertile eggs. So that can lower the population that you have. And while humans are, of course, naturally concerned about our own bodies when it comes to thinking of such an invasive parasite. What we also want to talk about, again, we're a One Health podcast, is that these often infect livestock, right? Or even pets. And so those are animals that might be more likely to be outdoors, might have little nicks or scratches, and they might have gotten a tick bite, and now there's a little bit of an open wound, and they might have caught themselves on a piece of fencing or just been out scraped a paw or something like that. And screw worms have caused hundreds of millions of dollars worth of damage to livestock operations, in addition to the human suffering that they've caused. And so the problem though isn't just that they eat flesh. I feel like that's a weird sentence to say. Normally that is the problem we have, is that they're eating living human flesh. But that's not the problem. That is a problem, but it's not the main one, right? It's that in doing so, as these larvae are like digging into the tissue and eating it, they're opening up the wounds further and further. And that can really allow for contaminants that are going to cause infection to enter and release become these infected wounds that are just crawling with parasites that are just only ever getting bigger, and that can cause eventual death for the animal as they get these really massive infections.

SPEAKER_02 8:04

That's for sure. Yeah. Yeah. It's really interesting to think about, though, this sort of strategy of for you have sterile insect release in order to go and control the population. Because I know normally when I think about controlling some of these pests that cause human and livestock infection, I tend to think of like spraying or things like that. But this is in many ways a lot less ecologically disastrous, right? In some ways, in terms of far fewer, you know, off-target effects both to humans and the rest of the ecosystem by just releasing these sterile males. Typically, yeah, it's like at a ratio of 10 to 1, 100 to 1, I think, aerially, right? In order to ensure

Life Cycle That Targets Wounds

SPEAKER_02 8:40

that there's a proper saturation of sterile males to females in the population, and then just subsequent surveillance efforts, right? To go and monitor and make sure that's that's maintained. Uh definitely an ongoing process. Seems like a lot of work.

SPEAKER_04 8:54

It is an ongoing process. And that's actually why we're talking about this today, right? Screw worms were technically declared eradicated in the United States in 1966. So not too long after Devil's Island, the penal colony, closed, screw worms were considered eradicated here. But they weren't actually what they had actually done, there's actually a lot of veterinary reports of screw worm cases that really contradict this idea of we had no more cases. We did have cases, but we were basically releasing enough of these flies, like you're talking about, Alex, that we were able to disrupt kind of the self-sustaining population of screw worms. And so that was what was really eliminated in the US. But we still had cases occurring, and it actually wasn't until we started working collaboratively beyond our borders with the 1972 Joint Mexico United States Screwworm Eradication Commission that we actually pushed screw worms out of the US entirely. And that was because we started to release these sterile screw worms and that the wild populations were then basically unsuccessfully breeding with, right? You had these unfertile eggs, and that lowered the population numbers enough that by 1980 northern Mexico was free of screw worms, and that caused us a major drop in US cases. And then the last case in the US was considered to be in 1982, or at least the last non-imported case, right? Because sometimes we would see them come animals or in people that had been in countries where it was still endemic. And so that was at least the case until recently.

unknown 10:18

Go ahead.

SPEAKER_02 10:18

Oh no, I was just gonna note as well that a couple of things that those eradication efforts also continued to spread beyond Mexico. So the biggest facility that still produces the sterile New World Screwworm male larvae is in Panama. And there were a number of efforts that followed after the 1991 declaration of New World Screwworm being eradicated in Mexico that focused then on Central America and then on pushing those New World Screwworm back to the Darien Gap, which is this remote mountainous area in the Isthmus of Panama, so the narrowest part of the continent that is difficult for the New World Screwworm to otherwise traverse. And so it was thought that the Darien Gap could be used as a biological barrier, especially once Panama, outside of the Darien Gap, was declared screwworm-free in 2001. But then, as you were alluding to, I think, Camille, there were issues in terms of like eradication is a very nice sounding word that wasn't exactly all-encompassing of what was really going on the ground. And a big issue with that was not just the infection of livestock, but also how wild animals then were a reservoir in some ways for new world screwworm infections in some of these places and were not really reported as heavily as these cases that would go and affect livestock, and that would affect in some ways human livelihood by going and affecting these animals. And so that enabled a natural place for these new world screwworm to hide away, so to speak, and then progressively also with these pressures that led to mass migration that caused more people to travel through the Darien Gap and potentially with them New World Screwworm 2 could follow that led to a drive of the New World Screwworm upwards back again into North and Central America, which coincided with then the decline of some of these facilities that were initially producing these male sterile screw worms. For instance, there was a facility in Mexico that the US government had that turned over to the Mexican government in 2012 that subsequently closed down. And there were other facilities that were run by the US government or in concert with other governments in the region that as a result of these declarations of eradication, screw worm no longer seems like that much of a priority, right? But it unfortunately, as we discussed, the work is ongoing. And if you take your foot off the gas, the screw worm put puts its feet back on the gas.

SPEAKER_04 12:43

Yeah, yeah. The screw worm starts, yeah, they show up. They start buzzing at your windows. Yeah. And I in in 2016, we first saw these really back on US soil without it necessarily being an imported case. We saw these in the Florida Keys and decimated an endangered deer population. And we're now seeing a resurgence of it starting in June 2026 in Texas. And as you were saying, this was really preventable, right? So what happens? And you're absolutely right. We basically only pushed screw worms out of our borders, right? And then we were like, uh, we'll put some funding towards it, but we won't keep pursuing it. And so we spoke before, like, this is a pretty problematic approach to assume that you can just keep something out of your borders and then it's no longer your problem, especially when it comes to disease. And we know that's not the case, right? We just have very porous borders, we're very globally interconnected. We move a lot of people, we move a lot of animals. And so to kind of assume that if something is just elsewhere, it's not going to come to your backyard is no longer really an accurate way of thinking or continuing to do business in the world. And we have such good techniques to manage these populations, but we stopped at just holding sort of this screw worm border with this release of irradiated steroflies in Panama, as Alex is mentioning. So but there's other things that also allowed things to move beyond the ones you highlighted. Illegal cattle smuggling also likely helped move the parasite northward, right? So people moving animals without bed chicks, like without papers, that can cause issues because they're potentially bringing parasites like screwing with them. And we

Sterile Fly Release Explained

SPEAKER_04 14:10

also likely saw some shift with COVID as well, right? Where there was this lapse in how things were functioning or what we were doing maybe for surveillance or what we were doing for maybe release. And so that likely helped it march northward again.

SPEAKER_05 14:22

Indeed. Yeah.

SPEAKER_03 14:23

Wow, illegal cattle smuggling just sounds to me like the craziest thing. You know what I mean? Like, how do you smuggle cattle? But I absolutely believe that it's a thing. I feel like us as humans, we'll find a way to smuggle whatever we can. So yeah.

SPEAKER_04 14:41

Yeah, and I think it's really interesting, right? Like growing up as a farm kid, when we would get cows from out of state, there's a massive amount of paperwork that you do, even to move something within the US, right? So just over a state, much less over the national border. Like if you were trying to move animals to Canada, you have to have bed checks, you have to prove that they're negative for these diseases, you have to prove they've been vaccinated for this or for that, they're not necessarily carrying any parasite loads, like stuff like that. And they do check it as a way of trying to prevent this movement of disease. But of course, there's always ways around that, and there's always reasons for people wanting to get around that. And there's potentially money to be made in getting around that. So because it takes a lot of time. But that also is one of the reasons we see disease move, is we're moving things without necessarily any surveillance on them for disease.

SPEAKER_02 15:25

And that's an issue, certainly, when it comes to preventing the spread of not just New World Screwworm, but anything from like cremia, conco, hemorrhagic fever virus on livestock and so many other of these things like that. And in fact, I think that we were talking a little bit about the kind of range of endemicity of the New World Screwworm really being in the Americas, right? In North, Central, and lots of South America with some seasonal variability in parts of its range in like parts of southern Argentina, because the colder winters are not exactly great for the New World Screwworm. But something that I thought was interesting on that point about how cattle smuggling, of all things, you think of like smuggling cattle, and I agree with y'all. It's just so ridiculous, it feels like as a concept. Pretty big, if you can go and move them without nobody noticing it. But yeah, something that I was reminded of in that regard was how there was actually a new world screw worm outbreak in the 1980s and 90s in Libya, of all places, which is outside of the area of endemicity. And it's unclear how it got there, but it's one of the rumored potential causes, certainly, is movement of livestock across borders, right? Because how else would the screw worm get over there? And whether that was legal or not, or if they were looking for it or not, is a different question. Because why would you be looking for New World Screwworm in Libya, right?

SPEAKER_04 16:41

So But it's not just livestock, right? Think about pets, think about shelter dogs, things like that. Animals that might have been living as strays in other countries. A lot of times, where I grew up in New York, you don't have a lot of stray dogs in like rural New York, but they would bring stray dogs up from the south that they would basically have in shelters, right? And sometimes those dogs are things like fungal infections that you only ever saw in the South. And so the vet when you would go in would be like, hey, did you adopt this dog? And then where did it come from? And sometimes, like now, Florida's gotten very nervous about what's happening in Texas, and they're like, you can no longer bring shelter dogs, you can't move them from Texas to Florida now because they don't want to risk bringing something like the screw worm in. And so I think that's also another route of transmission that we might not necessarily be thinking in some places, especially warmer places, there might be a higher proportion of stray dogs, right? Like that's definitely something that you see in a place like Galveston, Texas, versus, you know, somewhere up north. And so I think that's also an interesting thing to contemplate. That can also shift the spring.

SPEAKER_02 17:42

That's a good point, yeah. Yeah. It makes you think a little bit about some of those the quarantines, right? That I know I have some friends who've moved between like the US and Australia, and it sounded like it was a real pain to go and uh move their dog over as well. But those are there for a reason, and because exactly as you were alluding to, yeah, these pathogens can come over as well, and that's a terrifying prospect that you don't want to go and start a screw worm infestation in another country if you can avoid it.

SPEAKER_04 18:10

Yeah, yeah. Or even another state, right? Um so I think that's also something that's really being considered right now, where there now is this ban on rescue and shelter dogs coming into Florida from states like that. So yeah, so just also put this in context. To date of this recording, so we're recording this on July 5th, 2026. There have been 31 cases of screw worms reported in the US in Texas and New Mexico, right? So two states, but Mexico has had 31,323 cases since September 2025. Wow. So you can see that there's a really high proportion of cases, and that's for the entire country of Mexico. But if you think about that, that's right there, right? And so you can see that 31 cases might be underreported. And not all of those are active cases, and of course, out of that 31,000, a lot have been treated. And out of the 31 we have here, some have been treated. But we likely have more than we realize that we have currently in the United States.

SPEAKER_02 19:05

Um yeah, that's a terrifying prospect in that regard. That there's even more out there that we don't know about. That's a good point that you alluded to earlier, though, Camille, about how not all of those cases are necessarily active right now and how there are some treatments that are used out there. Yeah, certainly, even in response.

SPEAKER_04 19:23

But that's still pretty high. Oh, yeah. A place we had eradication, quote unquote.

SPEAKER_02 19:29

Eradication, I

“Eradication” And The Panama Barrier

SPEAKER_02 19:30

think not.

SPEAKER_03 19:32

Yeah, yeah. Okay. I do just want to point out too, though, that especially right now that we have the World Cup going on and it's specifically centered in Mexico and parts of the US, you might be afraid, hey, does this mean that the spread of screw worms is gonna just explode? And I think that it's probably important to just point out you can't typically just have screw worms living on your clothes or anything like that. They're not gonna survive in those means. So also want to put a PSA out there. Don't be afraid. Just don't go walking around with some open wounds in a place with a high problem of screw worms right now.

SPEAKER_04 20:09

I think this is a wonderful thing to bring up. I also want to mention we're saying these are cases that we likely got from Mexico, but it's important to keep in mind this was naturally here before we eradicated it. We pushed it on the United States, we pushed it out of Mexico, and we continue pushing it all the way down to Panama. But this is something that was naturally here, right? This isn't something that we're trying to say is like, oh, like it's coming from this state or that state, or it's somebody's fault. There's a lot of reasons why the kind of containment order broke. What's really interesting to contemplate is that we sort of made this problem ourselves, right? And that we probably could have kept pushing to irradiate more and more supplies, release them, and maybe help other countries out to prevent this from being an issue there, but we didn't necessarily do that, whether that was for money, whether that was for lack of collaboration. And so, in many ways, this problem is one that was always in the making, even from the very start of these commission's founding to quote unquote eradicate something.

SPEAKER_02 21:07

Yeah, because it was less eradication and more just pushing back the boundary of where it was in relation to it.

SPEAKER_04 21:13

Yes, pushing it out of my backyard, but then it goes into your backyard. Exactly. And then you're shocked when it comes back. It's like a weed, right? It's like I've weeded my garden and I've thrown it over the fence, and then eventually it's gonna pick up in your garden, and then it's gonna come under my fence and it's gonna let me grow again.

SPEAKER_03 21:31

Right. Exactly. So we can't be too upset at our neighbors or at other people when it just comes from.

SPEAKER_04 21:39

We will drop the ball on this, right? And this idea too that we'll just push something beyond our borders and then it's no longer our problem. We know that's not true, and yet we still didn't do the follow through that we could have. And so I think that's a really interesting question to pose to the group before we get into talking about like what the treatment for this is. Could we have eradicated screw worms entirely if we tried? And if so. Should we? And I think this is a really interesting question because a lot of times we, especially as biologists, we like to think of all species serve a purpose. I try to remind myself of that when I'm smacking mosquitoes. But we're like these cause so much damage. And obviously, we're the species that causes the most damage globally, everywhere, worldwide. And so it's kind of a hairy question, right? One, I read a lot of different experts' accounts before we did this episode. And I think people are, oh, there is no way we could have gotten rid of this everywhere. But I think we could have done more than we did, where we just pushed it to Panama and then we stopped. And I think that shows a lack of collaboration and also a lack of putting money towards preventing human suffering. So I think we could have pushed it further than we did.

SPEAKER_03 22:41

I was gonna ask you, Camille, and I'm glad that you brought it up. As we know, everything that's on this earth serves a purpose for the most part, even if we don't know what that purpose so much is, even though screw worms can cause so much damage. Is there any benefit to the ecosystem that screw worms break?

SPEAKER_04 22:57

Is it do you know? Not that I found, but that doesn't mean it doesn't exist. You don't know how key a species is until it's gone. We've seen that with species that have become endangered and then extinct where we didn't know that it mattered. Yeah. Yeah. And so it's hard to know. That's a really good question, though. And it's also like, do we have the right to eradicate something entirely if we don't know the answer to that question? Yeah.

SPEAKER_02 23:23

I yeah. What do you think, Alan? As far as what we've seen, it doesn't really seem to play a key role. Certainly, it's not a pollinator or something like that ecologically, and it's the it doesn't provide some unique food source by any means. If the screw worms of the world, uh screwworm flies died tomorrow all over the Americas, I don't think that there's necessarily one group along the food chain that's going to be shedding too many tears, so to speak, about this.

SPEAKER_04 23:51

Nothing warm-blooded that they were eating.

SPEAKER_02 23:54

Certainly. But I do think that that, yes, there are certainly some ethical questions because indeed there's so many of these biological questions with these complex systems that are the ecosystems that we live in, that we just aren't capable of answering necessarily in a vacuum. And it's possible, as you were alluding to Christina and Camille, that there may very well be more benefits out there. I think that if there was a good test case for eradication, this would probably be as good as you might get with a sort of obligate parasite like this. But yeah, it's a challenging thing, and we've seen how difficult it is, even with less complex organisms, less complex agents of disease to go and eradicate them. There's a reason that smallpox and rinderpest are the only ones that we've managed, and that's because of their epidemiological comparative lack of complexity, right? You know, when it comes to smallpox having its species. One species exactly becomes a lot harder when you're dealing with something like New World Screwworm that can be in so many, right? So I don't know if eradication is entirely possible, but I agree with you, Camille, that it feels like more could have and should have been done. And in some ways, by going and letting these efforts slow down over the course of the early 2010s and beyond, that we paved the path for this resurgence to ultimately happen. Also, COVID certainly didn't help with just how every public health agency was understandably focused on the major pandemic that was going on and resources got pulled back in other areas. And this was one of them.

SPEAKER_04 25:28

Yeah, it is a really interesting thought question because I don't really know if we could have gotten rid of it entirely. It's established in many places. It would have taken the dropping of billions of flies, right? To get rid of it entirely. But if we had collaborated and pulled together capital and things like that, could we have reduced it to the point where it could have been more manageable for everyone instead of only worrying about it when it's hit our borders, right? No one really talked about this. I feel like I knew about it in 2025 because I again I think screw rooms are fascinating. So, like if ever I see them in the news, I have my finger on the pulse of that because I think it's really interesting. But I don't think anyone, again, really talks about it until it hit our borders. Similar to we talked about this with Zika, right? It's not new, but it is new to us in this generation. And so I think that's something that is also deeply

Resurgence In Florida Keys And Texas

SPEAKER_04 26:20

problematic and shows us our own underbelly of issues as a society, right? That we're not worrying about it until it hits our borders, even though we certainly have a lot of trade and economic reliance with other countries that were affected long before we were.

SPEAKER_02 26:35

Absolutely. Yeah. So many of these countries in the areas that have been affected, be it Mexico and Central America, the US has so many significant trade ties to them. You know, CAFTA DR is the Central American Free Trade Agreement that we have, Kuzma, the free trade agreement. These are things that inherently make the travel of goods, and those goods include livestock and people, and those people include their pets, um, you know, means that it can be pretty challenging. And so, yeah, these are things that we have to pay attention to. I would say, though, to kind of not play devil's advocate, but just to maybe give a bit more grace, perhaps, to public health decision makers during these time periods, is that when you look at the trajectory of how things were going with New World Screwworm, right, where it seems like that biological barrier at the Darien Gap is intact in that early part of the 2000s and the early 2010s, it feels like why not focus on other priorities, right? Why not focus on trying to eradicate guinea warm or on rolling back malaria, right? Or on all of these other major diseases that affect especially humans. I think that's the other issue, that there's a lack of focus sometimes on animal health issues and how that comes back to us. Because just because New World Screwworm is a big issue more in livestock or in wild animals, doesn't mean that it doesn't affect us. And honestly, I think it would be so much fun to do an episode on animal pathogens one of these days here, um, because like there's so much that's out there. I digress.

SPEAKER_04 28:03

Yeah, and it's so interesting. I also want to highlight too, we're talking a lot about like the US-Mexico border, but other countries are worried about getting it from us, from the US, and particularly Europe is very concerned now about importing anything from us that could potentially bring screw range to their shores. And so I think that's also an important thing to highlight that we have these sort of trade agreements and our interactions in the world allow all things to kind of move with a bit more ease, and that always is going to include disease, because disease moves where people and animals do, and it doesn't know borders the way that we do. Because there are things we made up.

SPEAKER_05 28:38

Of course.

SPEAKER_04 28:39

Yeah. Yeah. But I do want to get into a bit about treatment of screw worms. So, Christina, you've touched on this. Treatment actually consists of manually removing larva, which is probably about as fun as it sounds. It can actually be really difficult, right? So they have these rows of like hooks and spines to stay embedded as they're like screwing into tissue. And oftentimes, in order to even be able to remove them from a wound, you actually have to apply like a substance that's going to start to suffocate them, like and cut off their oxygen. And that will basically bring them closer to the wound surface, trying to seek oxygen, and then you grab them in the mouth. Something like gasoline or like glycerol is put on the wound, and then they'll try to come to the surface. And that forces them to seek that oxygen. You can remove them. Antibiotics are often going to be needed, particularly some of these wounds get really big. If you can think of how many eggs a fly is potentially laying in even a small wound, and then they're all eating the flesh and they're just going out, these can become truly massive wounds. And so antibiotics are likely going to be needed in a lot of cases, and humans certainly as preventatives, and animals definitely just to try to keep them alive and functioning after something like an infestation. Insecticides are used in animals. Prevention, as Christian was mentioning, is really like covering wounds, wearing insect repellent, that kind of stuff to sort of keep these off you. And they don't go person to person, right? So, like you could basically remove these from a wound and probably be fine yourself. There are some instances where they can go through like healthy skin and just start eating in, but you'd probably be pretty fine to like remove them from a wound. But if you think about that, that is a massive undertaking. If you think of what I talked about in Mexico, where you have 31,000 cases, right? To remove the amount of larva that are in each of those wounds, it's a massive undertaking. Um and it's certainly got to be really quite painful, I would imagine, as well. Even if someone has had a local anesthetic or something, it's got to be very uncomfortable.

SPEAKER_03 30:29

Yeah, I can imagine. And then just like you said, the repercussions following wounds the size of that, it's the process of healing those wounds, which takes weeks, if not months, and preventing other overlying infections from occurring during that healing process as well, just makes this an even bigger undertaking than we can probably imagine at this point. I do think a really cool thing though to note for any pet owners or any cat and dog lovers out there, if you are concerned about your animal contracting screw worms or getting screw worms in a wound, like Camille said, make sure you're covering the wounds, keeping your pets and animals clean, but also preventative measures like your flea and tick prevention, NextGuard will cover screw worms as well. So that's just another way that you can get control before it happens.

SPEAKER_02 31:18

Indeed.

SPEAKER_04 31:18

Yeah, we always recommend flea and tick prevention because there's so many other diseases, but it also can help with screw worms. So if you're in Texas or New Mexico and you're worried about your pets, make sure they're up to date.

SPEAKER_02 31:29

100%. And it's worth noting in terms of your treatment options as well, if prevention doesn't necessarily work in some of these cases, that there are antiparasitics, say Laftalinur, which recently got an emergency use authorization in cats, for instance, more as well as in dogs. And so as a result of what's been going on, there has been much more research and much more of a focus on trying to develop and test some of these countermeasures in various animals of interest. And there has been a regulatory push as well, insofar as these emergency use authorizations and similar such sorts of instruments have been used by the FDA to try to control this. Yeah.

SPEAKER_04 32:08

Yep. And of course, an ounce of prevention is worth a pound of cure. So we are returning to irradiating screw worms, and we're releasing, and there's moves being made in the US to make that happen so we can prevent sort of this re-establishment of a population. And I'm very hopeful that we will continue these efforts collaboratively with other countries as well, to not just be like we're just gonna fix this for New Mexico or protect this, but to try to continue pushing screw worms further and further. I still don't really know where I stand on the whole should we eradicate them entirely thing, but I definitely think we could reduce the populations really significantly. And it's also very humane, right? We're irradiating them and then they're basically mating with these males that can't reproduce. And so you're not actively killing them off, you're just reducing their natural like reproduction rate. And then as you said, it's like it's pretty ecologically friendly. You're not putting out these really nasty insecticides or anything that could potentially have these off-arget effects that we don't want. So I think it's a really great solution that we have, and just ramping that all up will be really interesting. But yeah.

SPEAKER_02 33:09

I will just say one more quick thing about the arrangement of flies so people have an understanding of the sort of scale associated here. So the Panama facility produces about 100 million fly larvae weekly. The facilities that I know, and that's what's online right now, and that wasn't sufficient, clearly, because otherwise we wouldn't have this issue, right? And so there's a renovation of the facility that was in Mexico that's ongoing right now that the USDA is sponsoring to try to get

Treatment, Prevention, And Pet Protection

SPEAKER_02 33:40

an additional 100 million flies per week out there. There's a new facility under construction at Moore Airbase that'll also be aiming for about 100 million flies a week when it becomes operational in late 2027. And the aim is to scale it up to 300 million a week by 2028 at that one facility at Moore Air Base alone. So we might see the capacity for production of these new world screwworm flies that are sterile go up by as much as five times by 2028. So help is on the way, so to speak.

SPEAKER_04 34:11

Yeah. It is also kind of cool how they grow them. I don't know if you got into that, but there's basically these like big trays. They used to do it on room temperature ground beef. That's how they started this way back in the day, because they would eat their way through it. You didn't know I have to think. But it's true. But now I think they use this, or at least what I learned in 2016 chatting with them, it's this almost like level jello kind of thing. Yes, like blood jello, and they like dig their way through it in these trays, and that's how they get all the larva to eat until they become pupa, and then they can emerge as spies, and then they can essentially and then they can collect them and release them from planes, which is pretty pretty cool. That's so interesting.

SPEAKER_02 34:54

Yeah, so one thing's for sure. You couldn't pay me enough to work in that facility. The smell of that blood jello, I can only imagine.

SPEAKER_03 35:02

I was gonna say you can't pay me and Alex enough, but you probably don't even have to pay. Oh, yeah. I got invited to go.

SPEAKER_04 35:11

I still want to go. I still want to go visit. I just want to visit. I'm sure it smells disgusting, but I do want to go visit. I think it'd be so cool to see them all just crawling about. Because you're in the big cover all suites. Yes.

SPEAKER_03 35:24

I mean, if anyone's listening to this that works at a screw worm breeding facility, whatever you call them, hit up Camille. Uh account.

SPEAKER_02 35:34

Camille would be happy to visit. I have no doubt of that.

SPEAKER_04 35:37

Yeah. I'd love to come visit. I'd love to come visit. Cool, it'd be cool. Just just how cool that be. You're in this big warehouse and you're just surrounded by a man eating larva. That's so cool. You can basically say you've been on a set of a horse. It's pretty neat. I'm okay.

SPEAKER_03 35:56

Christina's gonna get it.

SPEAKER_02 35:58

I'm just gonna say this this might be stuff that your dreams are made of, Camille, but I think for me and Christina, it might be closer to our nightmares.

SPEAKER_04 36:08

I just think it would be. I don't know. I just think they're I just think they're neat.

SPEAKER_03 36:13

It is very cool, though. It's very interesting, it's very horror-esque.

SPEAKER_04 36:18

It's yeah, the monster from every yeah. When this first came out at 25, when I first saw something about an increase in cases in Mexico, I actually had tea late one night with a friend of mine who was also finishing her doctorate. And we're both really punchy, right? We were both coming up our own defense. And we sat there for four hours and outlined a horror novel about screw worms coming back to the United States and why it would happen. And I actually have like drafts of this sitting on my computer from last year. And then my mom sent me all these articles. She was like, Look, the screw worms are back. She's like, I know you love screw worms, look, they're back. And so she sent me like all these articles.

SPEAKER_03 36:52

I was like, I should have published supporting those kinds of hobbies and interests. Incredible. Secondly, Camille, I need you to release the novella, please.

SPEAKER_04 37:03

Yeah, no. I have the whole little draft out of why it happened. Yeah, but it was definitely a horror novel. Like it departed significantly into science fiction. But yeah, so if that's ever of interest in Fectious Science listeners, let me know.

SPEAKER_02 37:15

I assure you, Camille, if you will be among the first in line to buy the book. And honestly, I was gonna ask when you mentioned when we were talking about the sort of horror movie nature, if you will, of the New World Screwworm. I was just like, So when are we seeing a film adaptation that's loosely based off of the outbreak? Right.

SPEAKER_04 37:36

So there you go. Yeah, it's gonna be interesting. So I'm hopeful that we kind of get it under control. But um, but yeah, so back in 2025, that's what I was thinking about, just like on the eve of my doing this. I was just like, I should have been like writing, I like I had other things to be doing, but I was like, I drafted out an entire document that I haven't touched in a while. Okay, yeah. Just drafting out the science fiction novel of screw and stretching to the US because I was like, it's so implausible, but there's a chance. And look at where we are now in July 2026. We're all living in some old world here.

SPEAKER_02 38:11

There you go.

SPEAKER_04 38:13

Exactly.

SPEAKER_03 38:15

Exactly. That's so funny. But this has been super informative. Thank you guys so much for uh teaching me so much about screw worms. I'm glad that I am friends with screw worm experts like you guys who know so much about screw worms and about the history of screw worms and everything like that. I don't know if we're experts, we're just like geeks about it.

SPEAKER_04 38:37

It has been a solid decade since I was first handed a screw worm, and I'm still utterly fascinating. They're fascinating. Oh, Camille. I was 16. I totally contact the guy handed me a jar of husks of screw worms, and I was like, dude, this is really cool. What do you do for work? And he was like, I'm an infectious disease biologist. And I was like, that's gonna be my job. I actually used to want to work at one of these facilities to produce screw worms. That was a that was the original goal. Never say never, Camille. Yeah, no, it's okay. I'm really happy with what I do now, but I still think it's a cool job. It's pretty neat. Yeah, I grow man-eating flies for a living and I release them so you're safe at night. It's a superhero job, right?

SPEAKER_02 39:18

Sure, superman, yeah. No, missing Marvel superhero, yes.

unknown 39:24

There you go. There you go.

SPEAKER_02 39:26

Now we know what your comics would look like, Camille.

SPEAKER_04 39:30

Very true. Oh, we just seem to have like how the podcast trio is just saving the world one episode at a time. There we go. There you go. That can be your new token.

SPEAKER_02 39:40

Coming to the website.

SPEAKER_04 39:41

Anyways, thanks to all of our listeners. This has been a very fun episode, as always. Thanks for indulging our favorite fun tangents into

Scale-Up Plans And Closing Thoughts

SPEAKER_04 39:50

geekiness. We're so glad you're listening. And thanks always for joining us. And thanks to my two co-hosts because they're wonderful people.

SPEAKER_03 39:58

Thank you, Camilo, for doing so much work, prepping these video, organizing everything. You two, Alex, for doing so much research. I just love our team. And it was fun to see Dennis pop his head in real quick.

SPEAKER_04 40:10

Yeah, no, for sure. All right, thanks everyone for listening. Join us on the next episode. Let us know what you want to hear.

SPEAKER_01 40:18

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SPEAKER_00 40:29

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SPEAKER_01 40:38

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SPEAKER_00 40:47

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SPEAKER_04 40:54

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