transcript

Speaker 1:
[00:01] Radiolab is brought to you by Progressive Insurance. You chose to hit play on this podcast today? Smart choice. Make another smart choice with auto quote explorer to compare rates from multiple car insurance companies all at once. Try it at progressive.com. Progressive casualty insurance company and affiliates not available in all states or situations. Prices vary based on how you buy.

Speaker 2:
[00:25] Hey, I'm Molly Webster.

Speaker 3:
[00:26] Hey, I'm Mona MacGowker.

Speaker 2:
[00:27] Mona and I just made a snail episode. It's called Snail Sex Tape and we have not stopped talking about snails for like months.

Speaker 3:
[00:35] We've become deeply obsessed with snails.

Speaker 2:
[00:37] I think we should all get snail tattoos.

Speaker 3:
[00:39] Snail tattoo could be cute.

Speaker 2:
[00:41] But you know what you can get instead of a snail tattoo?

Speaker 3:
[00:43] What?

Speaker 2:
[00:44] You can get an enamel snail pin in honor of our snail sex tape episode.

Speaker 3:
[00:49] I've never been more honored in my life.

Speaker 2:
[00:51] I know.

Speaker 3:
[00:52] It is based on a real medieval snail miniature. I will be rocking it on my jean jacket all spring long.

Speaker 2:
[00:59] So to get one of these pins, you have to join The Lab. And when you join The Lab, in addition to helping fund our show, you get access to sponsor-free podcasts, plus monthly bonus content, plus invitations to events with the team.

Speaker 3:
[01:16] Including an AMA that we're going to be doing next month, you and me, about the behind the scenes of making snail sex tapes.

Speaker 2:
[01:23] Behind the Shell, BTS. All you have to do is go to radiolab.org/join. And if you use the code word snail, you get two months off the first year of an annual membership.

Speaker 3:
[01:34] Get your pen, and we can't wait to see you guys next month.

Speaker 2:
[01:36] Thanks everyone.

Speaker 4:
[01:39] Oh, wait, you're listening.

Speaker 2:
[01:40] Okay.

Speaker 3:
[01:49] Radiolab. From WNYC.

Speaker 1:
[01:56] Hey, I'm Latif. This is Radiolab. And today, I have with me a Sarah.

Speaker 5:
[02:02] Okay, no echo or anything?

Speaker 1:
[02:03] Nope.

Speaker 5:
[02:03] Okay, great.

Speaker 1:
[02:04] As in Radiolab reporter-producer, Sarah Qari. Can you hear me without an echo?

Speaker 5:
[02:08] Oh, yeah, no, you sound great. And Sarah's here in the studio.

Speaker 1:
[02:11] I have a Sarah.

Speaker 6:
[02:13] Hello.

Speaker 1:
[02:13] Hi.

Speaker 6:
[02:14] Hi, nice to talk to you.

Speaker 1:
[02:15] Sarah Zhang, who writes for The Atlantic and is a wildly prolific science journalist.

Speaker 6:
[02:20] Oh, thank you.

Speaker 1:
[02:21] Like, I feel like you cover COVID. I know you cover autoimmune diseases. I know you cover Ozempic.

Speaker 6:
[02:27] I'm sort of lucky enough to cover just, like, whatever I'm interested in.

Speaker 1:
[02:30] But we called her up because a while back, she noticed something weird happening to the deer in the Florida Keys.

Speaker 6:
[02:38] I don't know if you even know about the key deer. They're, like, really cute. They kind of, like, wait at bus stops and people like to feed them.

Speaker 1:
[02:43] Okay.

Speaker 6:
[02:43] And so back in 2016, a very grave situation for this endangered key deer. People suddenly started noticing all these, like, ugly, like, grisly wounds on these deer.

Speaker 7:
[02:53] Gaping holes or wounds in their neck or in their head.

Speaker 6:
[02:58] Literally, you could see down to the bone.

Speaker 7:
[02:59] Cruesome.

Speaker 8:
[03:00] Painful.

Speaker 7:
[03:01] It's a very sad sight.

Speaker 6:
[03:02] So it was, you know, it was kind of like a weird thing happening in Florida story.

Speaker 7:
[03:07] Yeah.

Speaker 9:
[03:08] But volunteers are teaming up to treat affected animals.

Speaker 6:
[03:11] What it turned out was that there was an infestation of an insect called the New World Screwworm.

Speaker 10:
[03:21] New World Screwworm.

Speaker 6:
[03:22] The New World Screwworm, also known as Flesh-Eating Worm. I had never heard about screwworms before. Yeah, me neither. No. I would imagine most Americans have never heard about screwworms before. The reason we don't know about it is because it's been eradicated from our country. I was like, what? That's crazy. I've never heard of an insect being completely eradicated from our country.

Speaker 5:
[03:49] As Sarah started to dig into this, it got even crazier and crazier. What she found was the amazing story of one of the biggest environmental interventions that humanity has ever undertaken. And the story of this worm, this honestly nightmarish flesh-eating parasite, that despite those efforts, is right now, today, back in the news.

Speaker 9:
[04:15] We are on screw-er watch and we are ready.

Speaker 5:
[04:18] Forcing public health officials and ranchers and ethicists.

Speaker 11:
[04:23] Here we are in the sixth major extinction that we humans are causing.

Speaker 5:
[04:29] To ask maybe one of the biggest questions that we as beings on this planet can ask.

Speaker 11:
[04:37] Would it ever be okay to bring about the extinction of a species?

Speaker 1:
[04:44] Oh boy.

Speaker 12:
[04:46] Yeah. But I mean, these are about the worst parasite on earth. I cannot imagine anything worse than these guys.

Speaker 1:
[04:52] So one of the first people we called when we got into this whole screwworm thing was the author Sam Kean.

Speaker 12:
[04:58] My name is Sam Kean. I am a science writer.

Speaker 1:
[05:00] Because it turns out he, like Sarah, at some point had fallen into the screwworm hole.

Speaker 12:
[05:06] Yeah. I had never heard of them. And I started Googling and then I went to Google images. And I immediately regretted doing that.

Speaker 1:
[05:15] And according to Sam, the reason that none of us had ever heard about what he called the worst imaginable parasite on earth is because of something that in 1970, the New York Times called the single most original thought of the 20th century.

Speaker 5:
[05:31] And it turns out that thought was born in the brain of a man named Edward Nippling.

Speaker 6:
[05:37] Edward Nippling.

Speaker 5:
[05:41] So as you know, Latif, when we first learned about this, I got obsessed and started doing some digging. And learned that Nippling has unfortunately passed away. But.

Speaker 8:
[05:54] Dr. Edward F. Nippling, we're happy to be here in your home today and thank you for participating in this oral history.

Speaker 5:
[06:00] I found this whole trove of interviews that he did back in the day.

Speaker 8:
[06:04] If you could start please by telling us when and where you were born.

Speaker 13:
[06:09] I was born in Port LaVaca, Texas, March 20th, 1909.

Speaker 5:
[06:14] Nippling grew up on his family farm in Texas and.

Speaker 13:
[06:17] In those days, farming was a very difficult occupation.

Speaker 5:
[06:23] Honestly, mostly because of the. What was I supposed to say after that?

Speaker 13:
[06:28] The screwworms.

Speaker 5:
[06:29] Oh, mostly because of screwworms.

Speaker 6:
[06:31] Yeah. So it was a problem for ranchers. Actually, I think this is a quote I remember. It was, screwworms used to strike fear in the hearts of ranchers all throughout the southern United States.

Speaker 1:
[06:42] Could we actually, could you just tell me what a screwworm even is?

Speaker 6:
[06:45] It is a fly. It has kind of like.

Speaker 1:
[06:48] Why do they call it a worm if it's a fly?

Speaker 6:
[06:50] Well, flies are also maggots, right? Like our flies come from maggots. So the maggot phase is a worm.

Speaker 1:
[06:55] Okay, okay, okay.

Speaker 6:
[06:56] So basically what they do is that if you have a little, like, nicking your skin, a little wound.

Speaker 12:
[07:01] Even something as small as a tick bite?

Speaker 6:
[07:03] These flies would lay their eggs in those wounds.

Speaker 12:
[07:06] Roughly 400 eggs at a time.

Speaker 9:
[07:08] Oh my god.

Speaker 6:
[07:09] And then these maggots essentially would come out. They kind of look like a small white thread.

Speaker 12:
[07:14] They have this kind of horrifying mouth with two sharp teeth and a little ridge on their body that sticks out exactly the way the threads on a screw do. They would twist themselves down.

Speaker 6:
[07:25] Kind of burrow themselves into the flesh, like a screw, and they would eat the flesh.

Speaker 12:
[07:35] And they are extremely hard to get out once they have locked in.

Speaker 13:
[07:39] A screw worm would get into the navel of calves when they were born.

Speaker 5:
[07:45] And so back to young Edward Nippling.

Speaker 12:
[07:47] He got probably the worst job on the farm, which was to pick the screw worms out of the family's cows.

Speaker 13:
[07:54] And that was a very unpleasant task.

Speaker 12:
[07:59] Have to try to yank them out of these animals that obviously aren't happy about this.

Speaker 1:
[08:03] Is there a tool you used? Like what are you-

Speaker 12:
[08:04] I'm guessing a tweezers or just fingers.

Speaker 1:
[08:06] Screwdriver. You got to use a screwdriver.

Speaker 12:
[08:08] That was his job. And it introduced a lifelong hatred of screw worms in his heart, understandably so.

Speaker 5:
[08:16] But at the same time, he has sort of a scientific bent of mind. He's curious.

Speaker 12:
[08:20] He was actually kind of fascinated by insects.

Speaker 5:
[08:22] Over time, he became a bug nerd.

Speaker 12:
[08:25] Definitely a bug nerd.

Speaker 5:
[08:25] Even named his cats after insects.

Speaker 12:
[08:28] One after a mosquito and one after a bull weevil. Antonymous and Culex. And when he grew up, grew up to be an entomologist. But also kind of in the back of his mind, he was always thinking, well, I have to figure out a way to control screw worm. I want to put a stop to them somehow.

Speaker 5:
[08:46] And as it happens, the first job I had, in the late 30s, he got a job at the USDA.

Speaker 13:
[08:52] As an entomologist working on the screw worm. That was the Bureau of Entomology and Plan Quarantine at that time.

Speaker 6:
[08:59] And then World War II breaks out.

Speaker 5:
[09:03] And the military enlists him in developing insecticides and repellents for use by the arm purpose.

Speaker 6:
[09:10] He actually ends up helping develop DDT.

Speaker 1:
[09:12] Oh, yeah, part of that one.

Speaker 6:
[09:14] And this is actually sort of part of his journey, which is that he saw insecticides can be really effective, but they can also be really devastating for the environment.

Speaker 5:
[09:22] So after the war, when he gets back to his screw worm job, he's just thinking about this problem.

Speaker 6:
[09:27] Like, how can we figure out a way to control insects that does not require spraying lots of poisons?

Speaker 5:
[09:32] And his way of trying to figure that out is watching screw worms mate.

Speaker 6:
[09:40] Just watching a lot of insect sex?

Speaker 1:
[09:41] As one does? Like, well, yeah, why?

Speaker 5:
[09:43] Why?

Speaker 6:
[09:44] I think he was just trying to understand these pests, right? To think, like, what could we do about it?

Speaker 1:
[09:48] Huh.

Speaker 5:
[09:49] And so one day a colleague of Nippling's is, you know, watching the screw worms have their sexy times. And he makes this observation.

Speaker 6:
[09:56] That sounds like maybe not that important or not that interesting.

Speaker 12:
[09:59] But that kind of hinted at something. He wasn't quite sure what exactly.

Speaker 6:
[10:06] Does that females only mate once?

Speaker 12:
[10:09] Whether or not they get pregnant, they get one shot to have intercourse and try to have eggs.

Speaker 5:
[10:17] I really feel for these females, like, this is such a high stakes. You have to have the best sex of your life in that one time.

Speaker 12:
[10:23] Yeah, that's it.

Speaker 5:
[10:25] But Knipling, he's looking at this and he's like, wait.

Speaker 6:
[10:29] If he could just do something to all of the males, right? Like, if he could just make the male sterile.

Speaker 5:
[10:35] And then if he could trick the female screwworms into mating with these sterile males.

Speaker 6:
[10:39] The females aren't gonna lay any eggs, they're viable.

Speaker 12:
[10:41] That would essentially take those females out of circulation for reproduction purposes.

Speaker 5:
[10:46] Their one shot would just be doomed to fail, basically.

Speaker 12:
[10:49] Yes, exactly.

Speaker 6:
[10:50] So just like, somehow flood the zone with sterile males is the idea.

Speaker 5:
[10:53] These poor females already had it so hard, and now he's just like ruining the dating pool for them.

Speaker 6:
[10:59] It's a little diabolical from the fly's perspective.

Speaker 5:
[11:03] But lucky for these screwworm ladies.

Speaker 12:
[11:05] It wasn't like that was a very practical idea.

Speaker 5:
[11:08] Because how would you even pull that off?

Speaker 12:
[11:10] You know, how do you mass sterilize a bunch of insects?

Speaker 5:
[11:13] But then he finds a paper.

Speaker 13:
[11:15] An article in Scientific Magazine.

Speaker 6:
[11:17] Basically since World War II, there's sort of like a lot of interest in like, what can we do with radiation?

Speaker 1:
[11:22] Oh, of course, right, yeah.

Speaker 5:
[11:23] And this paper was by a geneticist who was saying that...

Speaker 13:
[11:26] It is possible to sterilize fruit flies by exposure to x-rays.

Speaker 12:
[11:33] And I think he sort of jumped off of his couch and said, oh my God.

Speaker 13:
[11:38] Maybe we could sterilize fruitworm.

Speaker 12:
[11:42] This could be the solution to the problem.

Speaker 1:
[11:48] Okay, so what, yeah, what does he do?

Speaker 5:
[11:50] Well, so the thing he needs is a bunch of x-ray machines.

Speaker 12:
[11:53] But he decides he's not going to go public and try to get any funding for this.

Speaker 13:
[11:58] We knew that if the media got a hold of that, they could make quite a deal out of this.

Speaker 5:
[12:03] I mean, remember, he's working for the government. Like, taxpayer money is at stake here.

Speaker 6:
[12:07] What happens if the press gets hold of this and then we're just totally ridiculed for like...

Speaker 13:
[12:12] Wishing money or something.

Speaker 6:
[12:13] Watching insect sex all the time.

Speaker 5:
[12:16] Not in a weird way.

Speaker 6:
[12:18] Yeah.

Speaker 13:
[12:18] We were rather cautious about that.

Speaker 12:
[12:21] So he decides he wants to do this kind of on the down-low.

Speaker 5:
[12:24] And basically he gets one of his colleagues...

Speaker 12:
[12:27] To take a bunch of screw worms and sneak them into a nearby military hospital and use the x-ray machines there.

Speaker 5:
[12:37] Flesh-eating worms in a hospital. Great.

Speaker 12:
[12:39] Yeah, exactly.

Speaker 5:
[12:40] But how does he get the screw worms in?

Speaker 12:
[12:41] Unfortunately, we don't have many details about what he did to actually get inside there. I pictured him hanging out at the loading dock at night and grabbing the door right before it shuts, or Watergate taping the lock or something like that, sneaking through the hall. I believe they did this at night too. He had to be kind of clandestine about it, sneak around a little bit.

Speaker 6:
[13:02] They are literally putting these flies through the x-ray machine and be like, hey, what happens?

Speaker 5:
[13:08] But the problem with shooting a bunch of radiation at a bunch of flies?

Speaker 6:
[13:12] Is that you create all these mutations, a bunch of random mutations. So you might just kill the fly. That's kind of a problem.

Speaker 1:
[13:19] Right.

Speaker 6:
[13:19] So they found that they figured out the right dose, but they also figured out exactly when to put them through radiation. It's when the flies' testes are developing, right? Because that's like what you really want to knock out. So that happens to be between 5.5 and 5.7 days.

Speaker 1:
[13:35] So it's like they've got it to within hours.

Speaker 6:
[13:37] Yes, yes.

Speaker 5:
[13:37] And when they do that, bingo.

Speaker 6:
[13:41] It seems to work.

Speaker 13:
[13:44] Of course, the next thing was would they perform in a natural population?

Speaker 5:
[13:49] It's not enough to just do it in a lab.

Speaker 12:
[13:50] So then he decides it's time for a real world test, and he found an island off Florida.

Speaker 13:
[13:56] On the island of Sanibel.

Speaker 12:
[13:57] Sanibel Island.

Speaker 5:
[13:58] He shows up there with some of the radiated screwworms from his lab, releases them on the island.

Speaker 12:
[14:03] And it did not work.

Speaker 5:
[14:05] Like the population of screwworms stayed pretty much the same.

Speaker 12:
[14:08] The experiment failed, and Nippling was glad he hadn't said anything or, you know, gone after public money.

Speaker 5:
[14:13] So yeah, does he just resign to his failure?

Speaker 1:
[14:16] That's the end of the story? Yeah.

Speaker 12:
[14:17] No, not the end of the story.

Speaker 13:
[14:18] We were kind of stymied what to do for a year or so, and then I got a letter from a veterinarian on the island of Curacao.

Speaker 12:
[14:29] A Dutch island called Curacao.

Speaker 14:
[14:31] Where is Curacao?

Speaker 12:
[14:33] Off the coast of Venezuela. He wrote a letter and said, The goats here are being ravaged. I know you study this. Can you help us in any possible way?

Speaker 13:
[14:41] And I thought, well, this is just the place that we're looking for.

Speaker 5:
[14:45] And this time, Nippling wants to go all out.

Speaker 12:
[14:48] They were not going to take a chance that there would be too few flies.

Speaker 5:
[14:52] Like no more handful of flies from his rinky-dink lab.

Speaker 12:
[14:56] They're going to set up an industrial facility for making these flies.

Speaker 5:
[15:00] And like carpet Curacao.

Speaker 12:
[15:02] And really overwhelm them with the sterile males to make sure that they were doing everything they could to give this experiment a chance of success.

Speaker 5:
[15:10] So in this factory that they set up.

Speaker 12:
[15:12] They came up with a formula for the food that they were going to feed them.

Speaker 5:
[15:16] Okay. And it was ground horse meat.

Speaker 12:
[15:19] That they soaked in blood and they would let they get putrid.

Speaker 5:
[15:22] Wow.

Speaker 12:
[15:22] And then they would douse it with formaldehyde.

Speaker 14:
[15:24] Okay.

Speaker 12:
[15:28] So, yeah. And it was cheap enough to get, you know, so they knew they could produce a lot of this stuff pretty quickly.

Speaker 1:
[15:35] Okay.

Speaker 5:
[15:35] Why the formaldehyde? I don't know why that's such a weird-

Speaker 12:
[15:38] Apparently, they just like the formaldehyde. I don't know.

Speaker 1:
[15:40] Oh, wow. It's just a little extra kick. It's like hot sauce for them.

Speaker 12:
[15:45] So then from about March 1954, they are producing 170,000 of these sterile adults per week.

Speaker 5:
[15:54] They are feeding them this slurry, though at this point without the formaldehyde.

Speaker 12:
[15:57] It took 40 tons of the slurry to get that job done.

Speaker 1:
[16:01] Wow.

Speaker 12:
[16:02] And it was a smashing success. The population plummeted after they started releasing these flies. His big idea had worked.

Speaker 5:
[16:13] Back in the United States, The livestock people, especially, ranchers catch hold of this.

Speaker 13:
[16:18] They came to us.

Speaker 6:
[16:19] And they're like, wait, we really want this.

Speaker 12:
[16:21] Eventually, the clamor from ranchers got so big, Nippling decided, well, I think the time is right to try rolling out his screwworm strategy in the US.

Speaker 5:
[16:31] And so, armed with some funding from the USDA.

Speaker 15:
[16:33] This new technique for insect control is eliminating screwworms.

Speaker 12:
[16:37] The first big push started in about 1957.

Speaker 6:
[16:40] In Florida.

Speaker 12:
[16:41] And after about two years of dedicated work, they had eliminated them.

Speaker 5:
[16:45] Not just in Florida, but everywhere.

Speaker 12:
[16:47] East of the Mississippi.

Speaker 1:
[16:49] That is huge.

Speaker 6:
[16:50] And then it kind of keeps going west.

Speaker 5:
[16:53] The Texas Cattlemen's Association hears about it.

Speaker 12:
[16:55] I mean, it was a Texas-sized problem, well, they had.

Speaker 5:
[16:57] They won in two, so Nippling and his team.

Speaker 6:
[17:00] Ended up building a really big factory in Texas.

Speaker 15:
[17:02] Screwworm Eradication Headquarters, at Mission, Texas. Here millions of screwworm flies are being reared each day.

Speaker 6:
[17:08] All these, like, metal machines.

Speaker 5:
[17:10] Sarah told us about a similar factory she went to in her reporting.

Speaker 6:
[17:14] Many different rooms, sort of, like, all at different temperatures, different humidities, for each phase of the life cycle.

Speaker 12:
[17:20] I could not have imagined it smelled good.

Speaker 6:
[17:22] I'm sorry to say this, but what it reminded me of was the smell of a used tampon.

Speaker 1:
[17:26] Okay, it makes sense.

Speaker 6:
[17:27] Well, that's kind of a little bit bad, maybe.

Speaker 5:
[17:29] From these factories, they start releasing flies multiple times a week.

Speaker 1:
[17:32] So how do they do that?

Speaker 6:
[17:34] By airplane.

Speaker 13:
[17:35] These planes are being loaded with sterile male screwworm flies in Mission, Texas.

Speaker 6:
[17:40] Basically, they would fly these little, like, prop planes and release these flies in the air.

Speaker 12:
[17:45] They took them up in refrigerated boxes. They had to buy, essentially, cases of perfume and cologne and dump them on the boxes before the pilots would allow them in the airplanes. And then they would essentially open the hatch and just dump them out and let them fall down.

Speaker 5:
[18:01] Oh, wow. And at this point, the nippling strategy is working so well, screwworms are disappearing from all of the Southwest.

Speaker 12:
[18:10] They started marching their way down to the border, pushing it down, pushing it down.

Speaker 6:
[18:14] Eventually, people were like, well, screwworms obviously don't respect national borders.

Speaker 13:
[18:18] If we're really going to deal with a screwworm, we would have to enlarge the program.

Speaker 6:
[18:24] What if we just kept going?

Speaker 13:
[18:26] This operation can now expand into Mexico.

Speaker 12:
[18:28] You know, get them out of Mexico, then we go down country by country through Central America.

Speaker 1:
[18:33] That is so much ground to cover.

Speaker 12:
[18:36] Yep.

Speaker 5:
[18:36] And so all through the 70s, 80s, 90s.

Speaker 6:
[18:39] There are all these kind of international agreements.

Speaker 12:
[18:41] Frankly, this was a tough sell in some places because the US has a history of meddling in Central America.

Speaker 1:
[18:48] Right.

Speaker 12:
[18:48] Especially in this time. But despite that and despite political turmoil, revolutions and coups and things like that, holy, the disgust over screwworms was enough that all seven countries in Central America came to the table. And they started marching down, you know, a dozen miles at a time or so, just working down year by year, all the way down to the border between Panama and Columbia.

Speaker 5:
[19:10] And in 2006, all of North America is declared screwworm free.

Speaker 1:
[19:19] Wow.

Speaker 5:
[19:20] And that so-called single most original thought in the 20th century changes the face of the entire continent.

Speaker 1:
[19:25] Amazing.

Speaker 6:
[19:26] And to this day, you know, at the time I was reporting in, like, there are still, there's still a factory in Panama. It's still producing millions of screwworms, growing millions of screwworms every day, flying a plane. I think it was three times a week. And maintaining this, like, basically this, what they called of it, like a sterile insect barrier.

Speaker 5:
[19:45] The idea is that that area where Panama meets Colombia, the Jarian Gap, which I think it's been in use a lot for other reasons.

Speaker 1:
[19:53] That's like the most dangerous area for migrants, right?

Speaker 6:
[19:56] Exactly.

Speaker 5:
[19:57] But it's also one of the narrowest parts of the Americas, only about 60 miles wide.

Speaker 1:
[20:01] Okay, so it's like a natural choke point.

Speaker 5:
[20:03] Right.

Speaker 12:
[20:04] And because of that, maintaining that sterile screwworm barrier only costs $15 million per year, which is a pretty reasonable price compared to the huge cost if screwworms were just kind of running wild.

Speaker 6:
[20:18] Yeah, so when I was putting on this back in 2020, the money saved was estimated to be over a billion dollars a year, so a billion dollars saved compared to $15 million cost.

Speaker 1:
[20:27] Wow, so that's a pretty good return.

Speaker 6:
[20:29] And it obviously was more expensive when you were in the active eradication phase.

Speaker 1:
[20:33] Right.

Speaker 6:
[20:33] But the maintenance cost, you know, it's really not that much money for a government program. And it's just kind of an example of how with basic science, you don't always know exactly where it will go. But in this case, it ended up like creating this continent-wide, multinational collaboration that has been going on for decades and decades. And the fact that this all kind of started with someone like watching screw rooms meet in the lab and having an epiphany is kind of remarkable.

Speaker 5:
[21:03] Now, there have been a couple of small outbreaks here and there over the years, including the Florida one, the key 2016 one. But they've all gotten tamed down pretty easily. Like, it didn't take all that much to beat those back. But when we come back from break, all kinds of things are going to break loose. News, biological barriers, and maybe also Latif's heart.

Speaker 16:
[21:38] Hey, Lulu here, and this episode is sponsored by BetterHelp. It is March, in like a lion, out like a lamb, and somewhere in the middle, it's International Women's Day. And BetterHelp wants us all to just take a moment to consider the women in our lives, our personal lives, our society, and thank them for their strength and for all that they carry. That work matters, they matter, you matter, and therapy offers a space for all of us to take care of ourselves in the way we deserve. Think about the roles you play for the people you love. Think about how those roles, intentionally or not, weigh on you and, in the worst moments, work to weigh you down. Therapy helps create perspective, set healthy boundaries, and work toward balance. BetterHelp has loads of therapists, all of whom work according to a strict code of conduct and are fully licensed in the US. Why not give it a try? Fill out a short questionnaire, and BetterHelp will use their 12 plus years of experience to match you with one. If you aren't happy with your match, switch to a different therapist at any time. Your emotional well-being matters. Find support and feel lighter in therapy. Sign up and get 10% off at betterhelp.com/radiolab. That's better, help.com/radiolab.

Speaker 4:
[22:54] This is Ira Glass. On This American Life, one thing we like is a good mystery. Sometimes about really big things, things you hear in the news. But most times, the little mysteries are the best.

Speaker 14:
[23:05] Our Lost and Found is currently filled with pants. I don't know, I've never seen this happen.

Speaker 3:
[23:10] I've got skirts, I've got shorts.

Speaker 16:
[23:12] Wait, this is true?

Speaker 1:
[23:13] This is true.

Speaker 4:
[23:15] Mysteries of every size, each week, This American Life, wherever you get your podcasts.

Speaker 1:
[23:27] This is Radiolab, I'm Latif Nasser, here with producer Sarah Qari. Hello. And we've been talking to journalist Sarah Zhang and writer Sam Kean about screwworms.

Speaker 5:
[23:39] Right, the skin-crawly, flesh-eating parasite that we all forgot about because Nippling and hysterical flies drove it down south.

Speaker 1:
[23:47] All the way to a biological demilitarized zone at the very bottom of North America, AKA the southern border of Panama.

Speaker 6:
[23:55] Yeah. But in 2023, Panama suddenly started seeing a massive spike in screwworm cases, from like 25 cases a year to like thousands.

Speaker 12:
[24:11] And since then, it's only gotten worse.

Speaker 10:
[24:14] The parasitic fly is moving north.

Speaker 12:
[24:16] They have been steadily marching north.

Speaker 14:
[24:20] They've been found in Costa Rica, Nicaragua, Honduras, El Salvador, Guatemala.

Speaker 6:
[24:25] They're even in Mexico.

Speaker 10:
[24:27] Only 700 miles from the US border.

Speaker 5:
[24:29] And it turns out, it's basically getting closer every day.

Speaker 14:
[24:33] Less than 400 miles.

Speaker 11:
[24:35] 300 miles from Texas and the southern border.

Speaker 12:
[24:37] It's gotten as close as 70 miles or so from the US border.

Speaker 17:
[24:40] Whoa.

Speaker 12:
[24:41] This is an ongoing breaking news story.

Speaker 1:
[24:45] So what happened? Like how did they get past the biological wall?

Speaker 12:
[24:49] There are a couple of theories.

Speaker 6:
[24:51] One theory is that maybe the strain of screwworm that they were growing at the factory was not as effective anymore. Maybe the ladies out there caught on to what was going on and weren't meeting with them or something.

Speaker 12:
[25:01] Just general disruptions due to COVID might have weakened the production a little bit.

Speaker 1:
[25:07] Or maybe, Sam says, given that we live in a more and more interconnected world.

Speaker 12:
[25:11] Because it does still exist in South America.

Speaker 1:
[25:14] Where people and products and animals are moving from place to place. It was just a matter of time before these worms found their way through.

Speaker 12:
[25:21] The best guess is that people were smuggling cattle that were infected, and then it just got out.

Speaker 5:
[25:27] But, regardless, as of today, right now the screw worm, it's sort of like knocking on our doorstep.

Speaker 10:
[25:34] It's not a matter of if the deadly pest gets to the US, but when.

Speaker 5:
[25:38] And surprisingly enough, in this time of cuts to science funding and all that, and you know, the idea of building political will around something that everyone has pretty much forgotten seems dubious.

Speaker 6:
[25:49] The issue has also alarmed Washington.

Speaker 5:
[25:51] It actually does seem like the US government is paying attention.

Speaker 14:
[25:55] The US Department of Agriculture has snapped into action.

Speaker 5:
[25:58] And really just like Nippling's time, pretty much because of the cattle industry.

Speaker 18:
[26:02] Billions of dollars of losses a year.

Speaker 1:
[26:06] Of course.

Speaker 18:
[26:06] It could truly crush the cattle industry as well as other livestock industry in Texas.

Speaker 5:
[26:13] So the USDA has started to set up screwworm traps along the US Mexico border.

Speaker 9:
[26:18] Cut down the southern border.

Speaker 5:
[26:20] They have agents on horseback.

Speaker 18:
[26:22] Those are so-called tick riders.

Speaker 5:
[26:24] Patrolling the border for stray cows. They are pouring money into screwworm research. And of course, they are rebuilding Nippling's fly factories.

Speaker 12:
[26:33] They are now building a new facility down in Texas.

Speaker 5:
[26:36] Another one in Mexico. All told, probably in the next couple of years, we will be producing and releasing something like 500 million flies per week.

Speaker 1:
[26:48] Wow.

Speaker 5:
[26:48] And we probably will have spent hundreds and hundreds of millions of dollars.

Speaker 1:
[26:53] Do you see this as the modern cow factory farm system is unsustainable, and this is just one other band-aid to keep that system financially profitable? I could see an argument that's like, oh, this is just to help big rancher businesses.

Speaker 6:
[27:11] Yeah. Well, I think in a literal sense, this program was created to help ranchers. That is, in fact, the express purpose of the USDA. So I think I wouldn't even argue with that premise. But this does affect wild animals too. Right. In Central America, you used to see howler monkeys fall out of trees because they had become so disfigured and sick from getting infested by schoolworms.

Speaker 5:
[27:35] Beyond that, actually, this time around with this effort, it's not just the USDA that's involved in this program.

Speaker 9:
[27:42] So I'll try and make the case on the human side of things.

Speaker 5:
[27:47] So I talked to this public health official named Megan Nichols, who is at the CDC.

Speaker 9:
[27:52] And my current role is Incident Manager for our New World Screwworm Response.

Speaker 5:
[27:58] Because the CDC is worried about this outbreak too.

Speaker 9:
[28:01] And the thing that Megan pointed out is that these flies like to infest a wound.

Speaker 5:
[28:07] I mean, you know, wildlife or cows aside, screwworms will happily lay their eggs in pretty much any warm-blooded animal, including humans.

Speaker 9:
[28:16] And it can be a pretty small wound, like as small as a little cut or a bite on the skin.

Speaker 5:
[28:23] I read that they can also get in through just like bodily openings. Is that true?

Speaker 9:
[28:30] It is true. They are often attracted to mucous membranes, so eyes, nose, ears, urogenital. Oh, yikes. So, yes, and during this outbreak, there have been over 1,000 human cases, and the number continues to grow daily.

Speaker 5:
[28:48] And to be fair, you know, like not to fear monger here. This is not a pandemic level human health crisis. Most people that take precautions will be totally fine.

Speaker 9:
[28:57] But I also think very much about this on an individual level.

Speaker 5:
[29:01] And the kinds of individuals that would be the most susceptible to a serious screwworm infestation, like folks who can't get medical help right away, or people who are unhoused or have weakened immune systems, or even like kids with a lot of scrapes.

Speaker 9:
[29:15] They're the last ones that need to deal with something like this.

Speaker 5:
[29:18] And on the off chance that it does happen, it is kind of a horror show.

Speaker 9:
[29:22] One of the most impactful images that I have seen related to 2025 was patients that were lining the hallway of a medical treatment facility in a country that is currently part of this outbreak. And the patient was holding a bowl in which they were basically sneezing out and pushing out larvae from their nasal passage. And other people who were lining this hallway basically waiting to be seen because they were also needing to get the maggots out of their body.

Speaker 15:
[29:55] Oh my gosh.

Speaker 1:
[30:00] Okay, all right. I now, I see the point that this is more than just the cattle industry.

Speaker 7:
[30:08] Yeah.

Speaker 1:
[30:09] But I do now wonder if it's just going to keep coming back. Like, is this just an inevitable cycle that we're now stuck in? Like, we're just going to have to keep doing this.

Speaker 12:
[30:22] Yeah, you kind of are on a treadmill.

Speaker 1:
[30:23] You're on a treadmill.

Speaker 12:
[30:24] Using Knipling's technique, yeah. Yeah.

Speaker 5:
[30:27] But I did, as I was reporting on this, come across a different way that people are starting to think about screw worm control.

Speaker 12:
[30:34] So another option that is controversial, but scientists have been talking about it-

Speaker 5:
[30:39] This is something that Sam mentioned too.

Speaker 12:
[30:40] Is something called a gene drive.

Speaker 1:
[30:42] Okay. So what is that?

Speaker 12:
[30:44] It kind of goes around the normal Mendelian laws of genetics.

Speaker 5:
[30:48] Okay. So first of all, let's assume that you are a scientist that has modern-day genetic technologies available to you, and you introduce a killing gene into the screwworm population.

Speaker 12:
[31:00] You could make it lethal to be a female. So it could trigger something where females just don't get out of the egg stage.

Speaker 1:
[31:07] It's like a little time bomb in the cell.

Speaker 5:
[31:09] Yeah, exactly. And typically, if you were to try to do that, genetics would work its normal way, and that killing gene would only get inherited 50 percent of the time. And in every successive generation, it would become less and less common, and you'd have to keep reseeding that gene into the population. But this is where gene drives have a little extra trick.

Speaker 12:
[31:30] In a gene drive, there's closer to a hundred percent chance that the gene will get passed down.

Speaker 5:
[31:38] You can basically ensure that it'll get passed down every time. And so it's kind of like a set it and forget it kind of thing. Like you introduce the killing gene, and then you just let it have its way with the screwworm population.

Speaker 12:
[31:51] The screwworms are going to be out there reproducing and spreading that gene by themselves very quickly.

Speaker 5:
[31:56] And what that really means is eventually...

Speaker 12:
[32:00] It's going to wipe them out.

Speaker 5:
[32:01] Not just, you know, beating screwworms back down to Panama, but like truly and wholly eradicating screwworms. Extincting them. Extincting them off the face of the planet forever.

Speaker 1:
[32:15] I just, well, like, I don't want us to have to live with these, but I don't want us to kill them forever. That feels wrong. That feels like we're doing something untake backable that is not, that we should not be doing.

Speaker 5:
[32:30] Yeah.

Speaker 11:
[32:30] Yeah. So, I mean...

Speaker 5:
[32:32] But let me bring in one more person here.

Speaker 11:
[32:35] So, I'm Greg Kaebnick. I am a research scholar at the Hastings Center.

Speaker 5:
[32:40] Because I think he feels a lot of the same way.

Speaker 11:
[32:43] I mean, here we are in the early stages of the sixth major extinction, one that we humans are causing. And I mean, in a way, this seems like, gosh, joining forces with the other side in some way.

Speaker 1:
[32:58] Yes, yes, exactly.

Speaker 5:
[32:59] Well, but at the same time, Gregory has seen this potential use of gene drives coming on the horizon and really wanted to think about it more. So what he decided to do is get together a panel.

Speaker 11:
[33:11] I thought, I'll turn to some environmental ethicists, ecologists, conservation biologists, geneticists, entomologists, some people with a public health background, no one from the Texas Cattle Ranchers Association.

Speaker 1:
[33:22] We already know what they think.

Speaker 11:
[33:23] I thought it would be particularly interesting to bring together people who would be by and large kind of predisposed to want not to take out species. So we gathered at Arizona State in May 2024 for a day and a half of presentations and discussion. They considered a couple of the top nasty species, like the mosquito species that is the main vector of malaria.

Speaker 5:
[33:51] And one of them was screwworms. So the idea was to hash out some of the pros and cons for either side.

Speaker 11:
[33:58] You know, keep, eliminate, and sort of report out our findings.

Speaker 5:
[34:02] And given the group of people that were sitting at the table, they started out with some of the arguments that you might expect.

Speaker 11:
[34:08] We need to think about the value of species.

Speaker 5:
[34:14] Yeah. What do you mean when you say that?

Speaker 11:
[34:15] Yeah. I mean, there'd be different ways in which a species could be valuable.

Speaker 5:
[34:20] Like first off, there's some very practical ecological considerations.

Speaker 11:
[34:24] I mean, the main question is, what's it doing in the wild? You know, is it a pollinator? Turns out, screwworm is something of a pollinator. But is it? Yeah, it is.

Speaker 5:
[34:35] Oh my gosh.

Speaker 11:
[34:35] Yeah. But it's probably not a very important pollinator.

Speaker 5:
[34:41] Bees do it better.

Speaker 11:
[34:42] Yeah. The bees probably win.

Speaker 5:
[34:44] Then you have to consider whether some other animal needs to eat it.

Speaker 11:
[34:48] Probably. Sometimes.

Speaker 5:
[34:49] But it turns out it's not really a key food source for any other animal.

Speaker 11:
[34:52] Is it? Does it play an important role as a predator in keeping other species in check?

Speaker 5:
[34:58] I mean, obviously, in this case, yes, it is a predator.

Speaker 11:
[35:01] But according to Gregory, the animals it eats are already under pressure from human forces. So if anything, you want to ease the burden as much as you can on those species.

Speaker 5:
[35:16] Okay. But they did also consider some more abstract values that a species might have.

Speaker 11:
[35:20] You know, aesthetic.

Speaker 5:
[35:22] Aesthetic. Interesting.

Speaker 11:
[35:23] Educational, historical, scientific. I think that's the list.

Speaker 5:
[35:28] Or maybe we put it in terms of screwworm.

Speaker 1:
[35:30] Yeah. In my mind, I was thinking about it like, if you were going around the way you did and you opened it up to all your colleagues and then sitting there was a giant screwworm who is going to make the case to save itself. Yeah, like what's the best case that that screwworm would make?

Speaker 11:
[35:52] That's the hard case.

Speaker 1:
[35:56] Aesthetic, clearly.

Speaker 11:
[35:59] Yeah, educational, like don't mess with nature kids.

Speaker 5:
[36:04] You know, jokes aside, though, I mean, Gregory says, you know, people like him do actually put a lot of stock in the sort of intrinsic value of a species.

Speaker 11:
[36:12] It's this ingenious development in and of its own, right?

Speaker 5:
[36:16] You know, anything that's around today has been honed by millennia of evolution.

Speaker 11:
[36:21] And in that way, every species is a marker of the creative, natural forces that sustain life, that brought us into being. I mean, I feel like you have to try to put it in a practically poetic way in order to really convey what people are thinking. So Gregory's group, after about a day and a half of discussing all of this, we're all kind of exhausted and we're trying to like put it all together.

Speaker 5:
[36:46] And Gregory says, okay, we're going to go around the room one by one.

Speaker 11:
[36:50] And sort of put everyone on the spot and see what they thought. And we did so. And by the time we'd gone around, most people had, I think maybe everyone had actually said, yeah, screwworm looks like a pretty good candidate.

Speaker 1:
[37:14] Really? Like, that it would be okay to wipe this species off the planet forever.

Speaker 11:
[37:21] Yeah.

Speaker 5:
[37:21] How did that feel? Is that awkward?

Speaker 11:
[37:25] Well, I mean, it was just like, it was kind of like this serious moment. Everyone was sort of sighing, like, oh, I really don't want to vote for this, but it looks like maybe the case can sometimes be strong enough.

Speaker 1:
[37:46] But isn't there sort of, like, I mean, this just feels like, you know, an idea that always comes up with ecosystems. Like, we think we know, and then we don't. Like, there's always the knock-on effects that we never see coming, and we thought we knew everything, but then it surprises us, but there it is. Like, does it not feel like hubris to assume that we know everything that could potentially go wrong?

Speaker 11:
[38:10] Yeah. But we did, in fact, at least up until very recently, get rid of screwworm in southern North America and throughout Central America, and, you know, the sky didn't fall. Other species didn't wink out because they weren't able to eat New World screwworm anymore. So we have a little bit of a kind of preliminary...

Speaker 5:
[38:29] It's like experimental data.

Speaker 11:
[38:32] Yeah, kind of. Like that suggests that it's probably not really that important ecologically.

Speaker 5:
[38:40] So losing it, you know, doesn't seem to do any harm. And then on the other side...

Speaker 11:
[38:46] Part of what was so persuasive about it was that the death that it causes is exquisitely awful.

Speaker 5:
[38:53] I mean, with screwworms, did you guys consider alternatives to eradication?

Speaker 11:
[38:59] Like, if there were some other kind of treatment for it, some sort of medicine that you could take...

Speaker 5:
[39:04] Gregory says, if it was possible to separate screwworms from the thing that they do, or the disease that they cause of flesh being eaten, and if you could attack that disease, then great, you know? That's sort of the case with malaria and mosquitoes, where you can attack the disease, or in that case, the parasite, rather than the mosquito. But with screwworms, there's just no way to do that. Like, eating flesh is in their nature. It's what they do. There's just no way to make them like vegetarians, or make them uninterested in flesh.

Speaker 11:
[39:38] The only way you get rid of the disease is by getting rid of the fly. At least at the time that we were meeting and writing, there was nothing else to do, except take it out if you can.

Speaker 13:
[40:10] Uhhh, I don't know.

Speaker 1:
[40:12] I don't know. I want to agree with him, but I just, I don't know if that wins the day for me. Like, I don't disagree, but I just can't bring myself to agree.

Speaker 5:
[40:23] No, this is, you know, this is the part of the story where I feel like I agree with you. I don't know. I don't know what to do with the fact that I don't want screwworms to exist. You know, like I think about like the people in South America. We just stopped at Panama. I don't know. I don't want them to have to deal with screwworms and suffer. But at the same time, this stuff gets scary. I guess one thing I will say though, that Gregory did mention is that if we go down this path, theoretically, there is sort of an undo button here.

Speaker 11:
[41:02] You can definitely keep it somewhere else in a facility or frozen eggs or something, and if it were to turn out that-

Speaker 5:
[41:12] Like the cure for cancer was in the screwworm eggs or-

Speaker 11:
[41:16] Really vital to the life cycle of this frog species in South America or something like that.

Speaker 5:
[41:23] Some ecological Brub Goldberg machine got set off because we got rid of all the screwworms.

Speaker 11:
[41:31] It would be possible to achieve something like de-extinction with screwworms.

Speaker 1:
[41:36] To bring it back to seed it, fling it out of the plains the way we're flinging out the sterile ones.

Speaker 11:
[41:41] Yeah. And what we know from the outbreak in Central America now is that it can take off pretty well.

Speaker 1:
[41:52] Imagine the public campaign where it would be like, hey, everybody, remember how we remember how we remember how they used to exist. There's this one frog in Panama that this was really helpful for. So we're just going to drop these flesh-eating worms. We're just going to rain them down over you and your home. So one last thing before we go. Back in 2016, Edward Knipling and his screw worm research won a Golden Goose Award. If you haven't heard of it before, the Golden Goose Award goes to US government-funded science that sounds ridiculous but ends up changing the world. And Knipling's research was exactly that. Even years after it proved useful, members of Congress still ridiculed and scapegoated it.

Speaker 14:
[42:44] Frivolous pork projects such as the screwworm research.

Speaker 10:
[42:47] $35 million.

Speaker 1:
[42:49] As an example of government waste.

Speaker 14:
[42:50] Even though the screwworm has been eradicated in the United States.

Speaker 1:
[42:54] This is now the fourth Golden Goose-inspired story that we have done.

Speaker 5:
[42:58] Nice.

Speaker 1:
[42:58] We did one about cone snails called Golden Goose, one about a bacterium called the Age of Aquaticus, and one recently about honey bees called Time is Honey. And now this one, it's almost become like a sneaky little recurring series that, if you ever meet someone who doesn't believe that the government should fund basic science, just play them one of these. We'll link them all in the episode description.

Speaker 5:
[43:22] This episode was reported and produced by me, Sarah Qari, with reporting help from Latif Nasser. Our fact checker was Emily Krieger. Check out Sam Kean's podcast, The Disappearing Spoon. His episode about screwworms is linked in our episode description. Same goes for Sarah Zhang's latest story, In the Atlantic. And if you are interested in hearing more about Gene Drive's, check out our episode about it, the last 10 minutes of our CRISPR update.

Speaker 1:
[43:47] Thank you to James P. Collins, Max Scott, Amy Murillo, Daniel Griffin, Phil Kaufman, Katie Barnhill, Arthur Kaplan, Ron Sandler, Yasha Rohwer, and our gaggle of friends at AAAS who administer the Golden Goose Award, Erin Heath, Gwendolyn Bogard, Valeria Sabate, Meredith Asbury, and Joanne Padrone Carney.

Speaker 5:
[44:06] And the last, last thing. If you want more information on screwworm infested areas or how you can take precautions to be safe, there is a website you can check out. It is screwworm.gov.

Speaker 1:
[44:18] That's screwworm.gov. Sarah, I guess it's time for us to just screw off.

Speaker 5:
[44:24] Indeed.

Speaker 1:
[44:24] And we'll catch you next week.

Speaker 5:
[44:27] All right.

Speaker 19:
[44:42] Hi, I'm Gabby. I'm from San Francisco, and here are the staff credits. Radiolab is hosted by Lulu Miller and Latif Nasser. Soran Wheeler is our executive editor. Sarah Sandbach is our executive director. Our managing editor is Pat Walters. Dylan Keefe is our director of sound design. Our staff includes Jeremy Bloom, W. Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhu Nainasam Bandhan, Matt Keelty, Mona McGawker, Annie McEwen, Alex Neeson, Sarah Qari, Rebecca Rand, Anisa Vitsa, Arianne Wack, Molly Webster and Jessica Young, with help from Gabby Santus. Our fact checkers are Diane Kelly, Emily Krieger, Natalie Middleton, Anjali Mercado and Sophie Semayi. Leadership support for Radiolab's science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

Speaker 17:
[45:53] WNYC's journalism and storytelling is heard by millions of passionate listeners. Sponsors of our programming gain our listeners' attention and their respect. Learn about how your organization can support WNYC and WNYC Studios at sponsorship.wnyc.org.