Ep 192 New World Screwworm: Oh-oh here they come

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Speaker 9 One screw worm infestation that goes unreported could erase the tremendous gains that have been made in the Southwest against this insidious multi-million dollar pest, the screw worm.

Speaker 9 Eradication workers can protect the gains, but only if they know where the pest strikes. You can help.

Speaker 9 Stopping screw worms is your concern, especially if you own livestock or a dog or cat or any other pet. All of of you can help by finding and reporting screw worm infestations.

Speaker 9 Examine your animals at every opportunity. Look for cuts, scratches or other wounds.
If you find a wound that contains insect eggs or larvae, take about a dozen worms and all eggs from the wound.

Speaker 9 After you've taken the samples, treat the wound with approved insecticides. Place the samples in a container or jar.
in alcohol or water. At this point, speed is important.
Call your county agent.

Speaker 9 He'll tell you where to send the samples. He'll tell you what action to take.

Speaker 9 Positive identification will be made by experts and measures taken to eliminate the parasite.

Speaker 9 A screw worm infestation confirmed by positive identification sets off a series of emergency activities at screw worm eradication headquarters at Mission, Texas.

Speaker 9 Here millions of screw worm flies are being reared each day and made sexually sterile by exposure to gamma rays from radioactive cobalt.

Speaker 9 Released in special patterns and in large numbers, these laboratory-reared flies fight for us against an outbreak. These sterile screwworm flies mate with native flies, which in turn cannot reproduce.

Speaker 9 Release of sterile flies, combined with intensive livestock inspection and use of insecticidal treatments, has already stemmed outbreaks.

Speaker 9 This new technique for insect control is eliminating screw worms from the southwest. Complete success depends on quick discovery, quick reporting, quick action.
Remember, examine,

Speaker 9 collect,

Speaker 9 treat. Call your county agent and help stop screw worms.

Speaker 1 That's the whole episode, is it not?

Speaker 10 Isn't that amazing?

Speaker 1 It's so comprehensive.

Speaker 10 It's so comprehensive.

Speaker 1 I

Speaker 10 okay, so that was from,

Speaker 10 I found that on the USDA National Agricultural Library in like their screw worm exhibit. And it was a video produced in 1963.
And it's called Look Out for Screw Worms. And I just,

Speaker 1 it was,

Speaker 10 I think I didn't realize the extent to which screw worm was such a big deal during that time period for decades and decades and decades, enough so that there are like promotional videos like this.

Speaker 1 Right. Available.
I, I'm really excited, Erin, to hear you talk about the history because I was reading and didn't realize like a lot of the history of like ranching in the U.S.

Speaker 1 was driven by screw worm.

Speaker 10 Yeah.

Speaker 10 I know. I know.
And it's so funny. Yeah.
I mean, there's, there's so much to cover. We'll get into it all, but I like want to start right now, but we won't.

Speaker 1 I want you to.

Speaker 10 We'll start instead with introductions.

Speaker 1 Hi, I'm Erin Welsh. And I'm Erin Allman Update.

Speaker 10 This is this podcast will kill you.

Speaker 1 And today we're talking about screw worms.

Speaker 10 Screw worms. Specifically for me, I'm talking about New World screw worm.

Speaker 1 Yeah. Well, we'll go over both different types of screw worms, New World and Old World.
But realistically, we're mostly talking about New World screw worm today.

Speaker 10 The one that's been in the headlines.

Speaker 1 In the news.

Speaker 10 It's been in the news.

Speaker 10 Big time. It's going to be a really interesting episode and a little bit maybe creepy crawly.

Speaker 1 Only a little bit? A very, very creepy crawly.

Speaker 10 Yeah, some of the descriptions I have are hard to stomach.

Speaker 1 Okay, that's good. I don't have that many of those.
Okay, okay. I'm keeping it basic.

Speaker 10 But before we get into all of that, it is quarantining.

Speaker 1 Quarantini time.

Speaker 10 Yeah. What are we drinking this week?

Speaker 1 We're drinking the screw worm driver. Yeah.

Speaker 10 It's just a screwdriver. Screwdriver, which is

Speaker 10 vodka and orange juice and with the addition of a gummy worm.

Speaker 1 Gummy worm.

Speaker 10 To represent. I can't get a worm.

Speaker 3 Screw worm.

Speaker 1 We're getting real creative with these, Erin.

Speaker 10 You know, I think that's okay.

Speaker 1 It's totally fine. Okay.

Speaker 10 It has to be. It has to be.

Speaker 1 We can do nothing else. Yeah.
Yeah.

Speaker 1 But yeah, we'll post the recipe on the places that you can find it, like our website, thispodcastwillkillyou.com someday, but also definitely on our socials. This Podcast Will Kill You, what? Socials.

Speaker 10 Oh, I have, I tried to post one. I don't know if it works very well.
I can't figure out the dimensions, but hey, we're working on it. There's a way to do it.

Speaker 1 Listen, there's a way. There's a lot of other great stuff on our website.

Speaker 10 Yes, there is. We've got transcripts.
We've got references for all of our episodes. So if you want to read more about Screw Worm, that's a great place to go.

Speaker 10 We've got links to merch, to our bookshop.org affiliate account, to our Goodreads list, to music by Blood Mobile, a contact us form, a submit your first-hand account form, Patreon,

Speaker 10 other things probably. Check it out.

Speaker 1 There's a lot there. Yes.
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Speaker 1 Moving on.

Speaker 10 Moving on.

Speaker 10 Are we done?

Speaker 1 Should we? Yeah. Great.
Are you ready? Yeah, I am. I'm going to tell you about the biology of Screw Worm really fast so that you can tell me about the history.

Speaker 1 Okay, let's take a quick break and then we'll get to it.

Speaker 1 The star of today's show is the screw worm, which is a larval form of a fly.

Speaker 1 Most people, when we say screw worm, mean the new New World screw worm, which is the species Cochleomya homnivorax. Might have pronounced that wrong.

Speaker 1 Hominivorax. Listen.

Speaker 1 It's the New World screw worm, but there is another one, the old world screw worm, which is a species called Chrysoma besiana. Okay.

Speaker 1 And these are two different genera of fly, but both of them are blowflies.

Speaker 1 Overall, not entirely dissimilar to the flies whose larval forms, not that long ago, in an episode we hailed for the benefits of their ability to help heal wounds.

Speaker 10 Yeah, this may change our feelings on maggots, I think.

Speaker 1 It will.

Speaker 1 Because today we're talking about pretty much the exact opposite. Yeah.

Speaker 1 Unlike most other species of blowfly, the New World and the Old World screw worms, larval forms, feed not on necrotic or dead tissue, but instead on the warm and living tissue of warm-blooded animals.

Speaker 10 Yeah.

Speaker 1 So screw worms are a type of fly who lay their eggs in the flesh of living mammals in a way that causes really significant harm.

Speaker 10 Kind of like bot flies, but more harmful.

Speaker 1 Way more harmful.

Speaker 1 So that, so what I want to do in this part of the episode is really just kind kind of take us through like, what are these flies? What are their life cycles look like?

Speaker 1 And why do they cause as much damage as they cause? So that you can tell us about all of the history with them because I know it's really interesting.

Speaker 1 So adult flies of these, both of these species, they look fairly similar.

Speaker 1 Most of what I'm going to talk about is about Cochleomaya hominivorax or the New World screw worm, but it mostly all applies to the old world screw worm as well.

Speaker 1 They look a tiny bit different, but otherwise they're really quite similar.

Speaker 10 I'm so interested in their evolutionary history, which I didn't look up, like the relationship between them. Was it like independent? Yeah, anyway.

Speaker 1 Oh,

Speaker 1 I didn't look it up either, but that's really interesting. Like, how did they both end up evolving this way of life that's so different from all of their other brethren?

Speaker 10 Right. I mean, it's a great, you know, open niche, I guess.
Like,

Speaker 10 someone else has got all the dead ones. You can get the live ones.

Speaker 1 Right, exactly.

Speaker 1 Anyway. And so the adult flies,

Speaker 1 all entomologists everywhere are going to kill me for saying this. They look like a fly.
Okay.

Speaker 10 How big?

Speaker 1 Bigger than a house. How big? About a little bit larger than a house fly.
Okay. Okay.
Not a horse fly, a house fly.

Speaker 1 And that's literally what they look like because they aren't blowflies. A lot of the houseflies that we see, not houseflies aren't necessarily blowflies, but you see these around.

Speaker 1 They've got almost like a metallic-ish kind of bluish-greenish body, like most blowflies do.

Speaker 1 They have these big giant orangish eyes across their heads, and then they have these three black and gray stripes along their back. The old world screw worm has two of those stripes.
Okay.

Speaker 1 The new world screw worms are native to essentially the entirety of the Americas, though they are primarily a tropical species.

Speaker 1 They need warm, moist soils in order to complete their life cycle, which goes something like this.

Speaker 1 The adult flies emerge from the soil where they pupate.

Speaker 1 And it is only the adult females, as is usual for flies, who cause the majority of the problems.

Speaker 1 They mate just one time.

Speaker 1 This is important.

Speaker 1 Usually around day three to five of life, and then they start laying eggs right around that time, day five to seven after they come out of their pupal form.

Speaker 1 These flies lay

Speaker 1 200 to 300 eggs. Some estimates say as much as 500 eggs per clutch.
It keeps getting worse.

Speaker 10 Yep.

Speaker 1 Because they lay additional clutches every three to seven days for up to 11 clutches of 200 to 300 eggs in a lifetime.

Speaker 1 And we can air and math this, though we don't have to because it's all over the papers.

Speaker 1 They lay a maximum of 3,000 eggs per single female screw worm fly throughout the course of their 20 plus day adult life.

Speaker 10 I mean, that is some hard work.

Speaker 1 It really is.

Speaker 1 They also often leave each one of their clutches in like several different egg masses.

Speaker 1 So, not all like 200 in one spot. They'll lay them like over a course of a few minutes or a couple of hours and multiple times.

Speaker 10 Right. Don't put all your eggs in one lesion kind of a mentality.

Speaker 1 Exactly, Aaron. Exactly.
And they do. They lay their eggs in lesions on the margins of wounds on warm-blooded animals, mammals, possibly birds, though they don't tend to prefer birds, but they can.

Speaker 1 But all mammals. And they tend to prefer the kind of drier margins of fresh or bloody wounds compared to wounds that are severely infected or really wet or have a lot of like bacterial purulence.

Speaker 10 Right. They want the freshest of flesh.

Speaker 1 The freshest of flesh. And they especially prefer wounds that have already been infested with screw worms.
Kind of like a signal that gets sent out, like, hey, this is a really great wound.

Speaker 1 Go ahead and lay your eggs here. Yeah.

Speaker 1 However, they can also lay their eggs on other easily accessible parts of our like thin skin or mucous membranes. So say the corners of eyes

Speaker 1 or in noses

Speaker 1 or near the perineum,

Speaker 1 or especially in places like in, say, newborn mammals, like newborn cattle, or goats, or horses that have an umbilical

Speaker 1 stump that's not fully healed. That's a really common spot.

Speaker 10 Yeah.

Speaker 1 And then after a day or so, these eggs hatch into hundreds of maggots. the larval form of a fly.

Speaker 1 And these maggots eat their way in around and under the skin of their host literally burying themselves in the process which is how they get their name screw worm

Speaker 1 their wriggly little maggot bodies are even grosser looking than most maggots um they have

Speaker 1 is that a thing that you can do i mean that is a high bar like maggots are disgusting looking maggots are gross looking 100

Speaker 1 but these ones have particularly sharp hooks

Speaker 1 as their mouthpieces. Yep.

Speaker 1 And their bodies have these sets of rings that kind of point backwards of these spines, these rings of like, you know, like the kind of spines where like you can drive over them, but don't drive backwards.

Speaker 1 Yep, yep, yep. Yeah.
And that is what helps them literally corkscrew their way deep into the living tissues on which they're feeding.

Speaker 10 How big do these larvae get?

Speaker 1 Oh, that's a really good question. I actually didn't see anything about the particular sizes.
I mean, they're not large. They're small individually.
So, like maybe a few millimeters big.

Speaker 1 Okay. Okay.

Speaker 1 Yeah.

Speaker 1 They feed for about a week before dropping off to pupate in the soil for another week, and then they'll emerge as adult flies.

Speaker 10 And once they emerge, okay, so I'm thinking about like going to in a place where screw worm is present.

Speaker 10 How many, you said that the females only mate once, and so how many rounds of females in a year is happening?

Speaker 1 You know what I mean? Like,

Speaker 10 right? It's not like a one-time idea. If it's like one week, then do they overwinter, et cetera, that kind of stuff.

Speaker 1 Yeah, so I mean, they tend to live in the tropics. And in the tropics, they're there all year round, right?

Speaker 1 And so they're going to be continually, and each female, adult females live for about 20-ish days. Okay.
And then, you know, they're going to lay their eggs starting on day like four or five.

Speaker 1 And the eggs only take about a day before they hatch. And then they feed as larvae for about a week.
And then they pupate for about a week.

Speaker 1 And so their whole life cycle is maybe, what's that, like a little more than a month?

Speaker 1 Okay. And so you could be getting 12 plus rounds.
I mean, plus each female is laying like 3,000. 3,000.
Yeah. I can't even calculate.
That's a lot.

Speaker 10 It's just hard to comprehend like

Speaker 10 they, I feel like they would run out of living tissue to eat so many.

Speaker 1 Interesting. So

Speaker 1 it's actually really interesting that you say that because one of the one of the papers that I read was looking at like the oviposition behavior of these flies. And they were pointing out that like.

Speaker 1 If you look at the way that they oviposit and like how frequently they do it and how they lay their eggs in these like multiple different clutches and all of this.

Speaker 1 But they do it multiple times in their life, right? Like a lot of a lot of flies or other insects might just lay like one giant clutch and then go ahead and die.

Speaker 1 But the way that these particular screw flames do it, they at least in this paper were saying that this fits with this strategy of like exploitation, where they might be evolutionarily

Speaker 1 finding niches that aren't always there, right? In an environment that's not always favorable.

Speaker 1 And so you've got to be able to like take advantage, lay a whole bunch of eggs as soon as you can and as quickly as possible when you find the right wound because you don't know when you will again.

Speaker 1 Okay.

Speaker 1 Which suggests that in nature, the perfect wound oviposition site might have been harder to come by,

Speaker 1 but then enter livestock.

Speaker 10 Enter livestock. Yeah.

Speaker 1 And now there's basically free terrain.

Speaker 1 Because when I, before I started researching this and when I thought of like the wounds that screw worms were causing but also that they were first laying their eggs in I always thought of like a huge gaping like wound right like some kind of large hole some infected something but actually that's not the right image to have

Speaker 1 the types of wounds that these flies can oviposit in to begin with can be as small as a tick bite and often are from a tick bite. Exactly.

Speaker 1 And so it's any break in the skin, a scratch from a thorn or a fence wire. Like I said, the belly buttons of newborn animals, insect bites,

Speaker 1 the wounds that can then be caused are incredibly substantial. Right.

Speaker 1 And animals, especially livestock animals, can die within a number of days to weeks after infestation with a screw worm or it's multiple screw worms because of how deeply these screw worms can wander and destroy tissue along their way and because of things like secondary bacterial infections that can occur from you know just the open wound that is caused by these maggots

Speaker 1 uh so that's that's like mostly screw worms aaron

Speaker 10 and okay so between the old world and new world are there differences in the severity or in the number of eggs or you know whatever it is it's a good question it was like weirdly hard to find great papers on the old world screw worms

Speaker 1 um so from what i can tell they they don't tend to be maybe quite as severe or at least not as deadly as quickly okay okay um i don't i don't know exactly why like what are you know all of the specific differences between them um

Speaker 1 As I know, you'll probably talk about the biggest difference in how we've dealt with them is that there are not as many programs that are widespread to try and eliminate the old world screw worm.

Speaker 1 So it is very much still a problem throughout its distribution. I see.
Whereas we have changed the current distribution of the new world screw worm.

Speaker 10 Yeah.

Speaker 10 Against its will.

Speaker 1 Yeah.

Speaker 1 And then in terms of like, how do we manage it, aside from what you're about to talk about, I just keep like putting little.

Speaker 1 Putting little teasers out there.

Speaker 1 We don't have any kind of vaccine. We don't have any kind of like specific treatment for screw worms.

Speaker 1 It's basically when we're talking about livestock insecticides on the wounds or like insecticide dips and things to try and help prevent the screw worms infection to begin with.

Speaker 1 We can also use avermectins like ivermectin. So for humans, with when there is human infection, because there can be and there is, this is also a public health problem, not just a livestock problem.

Speaker 1 It requires oral ivermectin. And this doesn't like get rid get rid of the infection per se.
What it does is paralyze the larvae, which then have to still be removed thereafter. Okay.

Speaker 10 It paralyzes the larvae. How interesting.

Speaker 1 Yeah.

Speaker 1 Yeah.

Speaker 1 So our mainstay of dealing with the new world screw worm has been sterile insect technique.

Speaker 10 It's so cool.

Speaker 1 Prevention. Tell me all about it.

Speaker 10 Is it my turn, really?

Speaker 1 Yeah, I don't have any more. Great.
Two tracks is going to be basic and straightforward.

Speaker 10 I'm excited. All right, let's get started.

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Speaker 10 So, to help me set the stage for the history of Screw Worm, I've brought along some assistants, Erin.

Speaker 1 I can't wait.

Speaker 10 Please open the video titled Screw Worm One.

Speaker 13 300 million years before man appeared on Earth,

Speaker 13 the insect was here.

Speaker 13 With time to develop varieties so diverse, their numbers are beyond conception.

Speaker 13 Roughly a million species.

Speaker 13 Along with ticks and mites, three-fourths of all the animal kingdom.

Speaker 13 Of these,

Speaker 13 10,000 species are man's mortal foe,

Speaker 13 endlessly vying with him for food and fiber,

Speaker 13 endlessly looting what he has sown and tended.

Speaker 10 Did you like that?

Speaker 1 I loved it, Aaron. I really hated the grub.
Those were grubs, not maggots.

Speaker 10 Listen, the video is like everything. Grubs count.
Grubs count too.

Speaker 1 That was clear.

Speaker 10 It's so fun. So that, I loved it so much.
That video is from, it was produced by the U.S. Department of Agriculture, the U.S.
DA, in 1969.

Speaker 10 And it goes into some of the various like insect and plant pests, including

Speaker 10 screw worm that have been plaguing farmers across the globe. I also thought it was interesting because it was like 1 million species.
And I looked it up.

Speaker 10 And I think we're now at like like 5.5 million species.

Speaker 1 Yeah, it was like 1 million. That's such an underestimate.

Speaker 10 Right. It's like Dr.
Evil, like $1 million.

Speaker 10 Like, that's kind of what it reminded me of.

Speaker 1 1 million species.

Speaker 1 Yeah.

Speaker 10 But yeah, I went all in on video clips for those episodes, as you're about to find out. So, yeah, there's an amazing archive work at the National Agricultural Library on the USDA website,

Speaker 10 as well as the Internet Archive, which is just one of my favorite things in existence.

Speaker 10 But I wanted to start the history of Screw Worm with that clip because I feel like it transports us back to a time when New World Screw Worm was among the top threats to agriculture here in the U.S.

Speaker 10 And by the way, I'm going to just be focusing pretty much only on New World Screw Worm for this, which I'm just calling Screw Worm for short.

Speaker 1 That's what most of the literature does. That's why it was hard for me to find stuff on Old World Screw Worm.
Yeah.

Speaker 10 But its eradication from North and Central America in 1991, which spoilers, it was eradicated and spoilers, it's back, marked a tremendous achievement in pest control and a demonstration of what was possible without the use of toxic pesticides.

Speaker 10 It was a big deal. Hence, the sheer volume of material that's out there about the screw worm eradication program.

Speaker 10 And after it was eradicated, it dropped out of the news cycle for the most part, except, of course, in the places where it was still prevalent, like most of South America.

Speaker 10 And the recent headlines about the re-emergence of screw worm here in the U.S., that might be the first time that many people have learned about or heard of this parasite.

Speaker 10 But in fact, it has plagued wildlife, humans, livestock in the Western hemisphere for thousands of years.

Speaker 10 And so using genetic analyses, researchers recreated the historical spread of this parasite and found that it seemed to follow human migration throughout the Americas.

Speaker 1 Interesting.

Speaker 10 Yeah, as human migration migration continued across North America and then down into Central and South America, the screw worm followed them.

Speaker 10 And then the introduction of European livestock starting in the 1500s, of course, provided even more hosts.

Speaker 10 And wherever it went, as long as it found a host on which to feed, and it wasn't too picky, it'll pretty much feed on anything that has living flesh. And with

Speaker 1 flesh, yep.

Speaker 10 And with suitable climate conditions, it would just do its horrific thing wherever it could.

Speaker 10 And so last season, we talked about how we did this episode on medicinal maggots and raved about how cool they are, which is so true. But the meiasis from screw worms is another matter entirely.

Speaker 10 It's not the same. It is not the same.
I found a quote from C.E. Scruggs from 1975 that I think pretty much sums it up for me.

Speaker 10 Quote, it is doubtful that the mind of man could create a more vile scene than that of worms consuming the live flesh of one's body.

Speaker 10 The imagination almost refuses, particularly in this day and age, to conjure up the horrendous pain and outright revulsion that must come to a person infested with a writhing, seething mass of worms steadily tearing and consuming his flesh.

Speaker 10 End quote.

Speaker 10 It's, I mean, it's truly awful.

Speaker 1 It is truly awful. Yeah.

Speaker 1 Yeah.

Speaker 10 And this

Speaker 10 feeling, this image, this sentiment towards meiasis, this might have been what the guy who first described the New World screw worm was thinking when he gave it the name, the species name of Haminivorax, which is man-eater, is what it translates to.

Speaker 10 And so the guy who did this was named Charles Cocherel. He was a surgeon in the French Navy stationed at a penal colony, Cayenne, in French Guiana, in the mid-19th century.

Speaker 10 Conditions at this penal colony were so awful, apparently, that it was given the name Devil's Island. And while he was there, he treated five men who were suffering from screw worm infestation.

Speaker 10 Flies had laid eggs in each of their nostrils and masses of larvae developed in their nasal sinuses, consuming the surrounding tissue.

Speaker 1 I know.

Speaker 10 Three of the five men died as a result of these infestations, and apparently 300 larvae were recovered after rinsing the sinuses out with water.

Speaker 1 Yeah. Yeah.
Nasal passages seem to be a really common place when there's human infestation.

Speaker 10 That makes sense.

Speaker 1 You just can't get at it as easily. Yeah.
Well, and a lot of times too, there's like, there's...

Speaker 1 there's something else going on like you like you're in a place where you don't have access to be able to move around or clean your surroundings or whatever um or that you're sick with something else so you're not able to like swap flies away that's that sort of a thing um but it's still it's oh it's it's truly it's, it is truly awful.

Speaker 10 And I think that Cokerell himself was quite a bit taken back by what he saw.

Speaker 10 And he wrote in this description of treating this, these men, that science is, quote, powerless to prevent these terrible ravages.

Speaker 10 And in that, he would ultimately be proven wrong, but it would take another hundred years or so for science to have a fighting chance.

Speaker 10 And in the meantime, screw worm continued its path of destruction.

Speaker 10 In the second half of the 1800s, cattle ranching expanded greatly across the southwest U.S., especially Texas, and millions of acres were transformed by grazing and also for grazing.

Speaker 10 Windmills were built to bring water to the surface for water holes. Screw worm flies like water.
So that was one, you know,

Speaker 10 helping it along. Overgrazing meant fewer prairie fires, so more continuously occupied habitat, more continuous host for the screw worm.
Okay.

Speaker 10 And deer replaced antelope as the dominant game animal, which grew even more abundant. So like deer herds, of course, are like, can be enormous.
So that's like even more hosts for the flies.

Speaker 10 According to one researcher's observation from 1959, deer are often victim to repeat infestations, leading to 2,000 to 3,000 larvae in one wound.

Speaker 1 Oh, goodness.

Speaker 10 And that amount of MAGA, so 2,000 to 3,000, can destroy an area apparently seven inches wide and seven inches deep or 18 centimeters wide and deep.

Speaker 1 Seven inches deep. How many areas on a deer's body can you go seven inches deep without hitting some vital structure?

Speaker 10 Yeah,

Speaker 1 I guess you that's you can't. Yeah.
Yeah.

Speaker 10 I mean, wounds like these are, can be deadly, are often deadly. And in bad years, up to 80% of fawns of white-tailed deer were killed from these infestations.

Speaker 1 Yeah.

Speaker 10 And these deer also provided ample hosts for ticks, specifically the Gulf Coast tick or Amblium immaculatum, which prefers to feed on the ears of livestock.

Speaker 10 And as we know, screw worms can lay their eggs in any wound, including tick bites, and cows' ears are often a casualty. You can tell, is this a screw worm-infested area?

Speaker 10 Because all of their ears are just like gone or shriveled or yeah, partially torn.

Speaker 10 And apparently, up to 90%

Speaker 10 of some screw worm lesions start from a tick bite in some areas where the tick is especially prevalent. And then others through common farming practices like castration, branding, dehorning.

Speaker 10 And then like you mentioned, newborn livestock are often infected at the navel.

Speaker 10 And

Speaker 10 on top of that, so we've got all these things going on, right? Like we've got more cattle, we've got water, we've got deer, we've got fewer prairie friars. This is all happening.

Speaker 10 And then you've also got the demand for beef skyrocketing since the development of refrigeration allows you to ship the meat that you don't sell locally, which previously had restricted herd size.

Speaker 10 And so now you've got the opportunity to create these massive herds because you can ship.

Speaker 1 Ship it. The meat.
Oh, wow, Aaron.

Speaker 10 Put it all together. And what you have are the perfect conditions for a screw worm storm.

Speaker 1 Just takeover.

Speaker 10 Just absolute takeover. And this parasite truly plagued the areas where they were established.
And it was a horror for livestock owners. Quote, this is a quote from one of these owners.

Speaker 10 A particularly disgusting and sickening job was when cows or calves got screw worms in their mouth and gums. This came about in two ways.

Speaker 10 One, the cow or calf, if they could reach the wound, would try to lick the worms out of the lesion. Thus, some live worms would get in the mouth of the animal and take hold.

Speaker 10 In some cases, I'm sure that flies would also lay eggs in the mouths of the newborn calves. You couldn't use any medicine.
Just remove the worms and hope you get them all.

Speaker 10 Some cases would be so bad that an animal might lose some of their teeth. It sure wasn't a job for anyone with a queasy stomach.
⁇ End quote.

Speaker 1 Oh, I've seen some pictures of that in like sheep's mouths, and it's so awful, Aaron.

Speaker 10 Awful. And so you're trying, I mean, imagine.
You have a herd of cattle and you have to spend so much of your time trying to do this.

Speaker 10 Like it was a losing battle, too, because as you mentioned, infected lesions will attract more flies.

Speaker 10 So they ooze a quote straw colored and often bloody discharge that attracts more flies resulting in multiple infestations by hundreds to thousands of maggots of all sizes.

Speaker 10 Death is inevitable unless the animal is found and treated, end quote.

Speaker 10 The horror of screw worm infestations was deepened by how inevitable they seemed. You could react, you could treat the animal, but how do you prevent them from attacking in the first place?

Speaker 10 Part of the issue was a misunderstanding of the screw worm's biology, which was only corrected in 1933.

Speaker 10 So, for decades, the screw worm was misidentified as just a regular type of blowfly, one who primarily fed on carrion and only on live flesh sometimes.

Speaker 10 So, it was like an opportunistic live flesh feeder. And so, it was thought, okay, well, if you get rid of all the carcasses on your rangeland, that is going to prevent the screw worm from

Speaker 10 being a problem.

Speaker 10 But since it feeds exclusively on live flesh, it actually doesn't really do anything.

Speaker 1 Right.

Speaker 10 And so recognizing that aspect of its biology was a huge step forward, and that happened in 1933.

Speaker 10 And around the same time, there was another development that would revolutionize the way that we dealt with screw worm. And that was

Speaker 10 a newly minted entomologist joining the cause. In 1934, Edward F.

Speaker 10 Nipling, a recent master's graduate from Iowa State University, started work at the USDA where he was tasked with, among other things, collecting and counting screw worm flies caught in traps.

Speaker 10 Nippling was no stranger to screw worm. He grew up on a farm in rural southern Texas.
He was one of 10 kids, and the farm is how they produced most of the food for his big family.

Speaker 10 So they would all be, you know, take part in, you know, dealing with the livestock. And he described removing, having to remove and look out for screw worms, among other agricultural pests.

Speaker 10 Before he went to college, he was aware of screw worm and the problems that it could cause, but it was at university that he gained a fuller perspective of how much insects have affected humanity, not just as livestock or agricultural pests, but also as vectors of disease, killing hundreds of millions of people around the world.

Speaker 10 He knew that control of these disease vectors and agricultural pests could save lives and livelihoods.

Speaker 10 And so while working at the USDA, he got to see firsthand how powerful some insecticides were, like DDT, which was just sort of like, you know,

Speaker 10 really

Speaker 10 this like revolutionary thing, kill it all.

Speaker 10 And also how quickly they lost their potency as insects grew resistant, not to mention the toxic impacts of some of these pesticides. Right.

Speaker 10 And so he realized that a a different, more proactive approach was needed. Aaron, play the clip titled Screw Worm 2.

Speaker 1 Okay.

Speaker 1 This is so fun.

Speaker 1 Screw worm two.

Speaker 14 What we really need is some way to control the screw worms before they

Speaker 14 attack the animals. And rather than

Speaker 14 Then just wait until after the animals had the screw worm and then try to control it.

Speaker 14 I realized that

Speaker 14 you would never, never really control the screw worm that way. What we needed was some preventive measure.
But

Speaker 14 how

Speaker 14 to control a screw worm on hundreds of thousands of square miles of

Speaker 14 territory of course seemed like

Speaker 14 a tremendous undertaking

Speaker 14 and

Speaker 14 the use of insecticides or something like that seemed out of the question and no doubt was

Speaker 14 but then I

Speaker 14 conceived the idea that

Speaker 14 perhaps we could

Speaker 14 rear the screw worm and

Speaker 14 have it some

Speaker 14 genetic deficiency

Speaker 14 that then

Speaker 14 it would release and release those genetically deficient insects into the population. They would mate with the

Speaker 14 normal flies and transmit

Speaker 14 detrimental characteristics. Just how I

Speaker 14 came to that

Speaker 14 conclusion,

Speaker 14 I really have a little difficulty even today,

Speaker 14 but

Speaker 10 isn't that amazing?

Speaker 1 He's He's like, I just kind of knew we had to do it. Don't know why I knew it, but I did.

Speaker 10 He's like, I did. Yeah.

Speaker 10 He's like, I don't know. I have this brilliant idea, and I have no idea how I came up with it.

Speaker 1 I love that. I love that.

Speaker 10 So that was, yeah, that was, that was Dr. Nippling himself interviewed in January 2000 as part of an oral history project for the Screw Room Eradication Program.

Speaker 1 Yeah. Wow.

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Speaker 10 And so, what he's talking about here is what you mentioned, Erin, which is the sterile insect technique, which is an insect control measure where large numbers of flies are made sterile and then released, ultimately leading to a massive decrease in wild population sizes.

Speaker 10 And the idea behind this is that the sterile males

Speaker 10 that are released will mate with the females. They won't produce any eggs.
And so there will be fewer and fewer screw worms over successive generations.

Speaker 10 And there are a few aspects of the screw worm's biology that help this technique to be successful. The first is that screw worms, like you said, Erin, tend to mate just once.

Speaker 10 And so if they mate with a sterile male, there's no viable offspring.

Speaker 1 Yeah. That's it.
And the females mate once, but the males mate like up to 10 times.

Speaker 10 Yes.

Speaker 1 Yes. So one sterile male could be mating with 10 non-sterile females, and then they're not laying any eggs.
Yep. Yep.

Speaker 10 And then the second thing is that in the screw worm-affected areas in the U.S., which is more like subtropical, only a small proportion can survive over the winter.

Speaker 10 And so if you hit that area hard enough with sterile flies one year, you can really make a dramatic impact.

Speaker 1 And so that's really reduce that population size to begin with. That actually makes a lot of sense.
Yeah.

Speaker 10 Nibbling wasn't the only one to come up with this idea or idea similar to this, like eradication or elimination via sterilization.

Speaker 10 There were a few other scientists that also proposed something similar in like the 1930s and 40s, but he was really the only one or the first one to get it off the ground.

Speaker 10 And for a number of years, you know, after coming up with this idea, he was like, okay.

Speaker 10 He had the idea first and then he was like, how do I actually implement this? Like, what?

Speaker 1 How do I make them sterile? Yeah.

Speaker 10 Right. And he, a colleague in 1950 was like, hey, have you, have you heard of this paper? Have you read this paper by H.
J. Mueller? He used x-rays to make Drosophila fruit flies sterile in 1928.

Speaker 10 That's when the paper was published.

Speaker 10 And Mueller had actually been awarded the Nobel Prize in Physiology or Medicine in 1946 for what he had shown in that paper, that mutations can be induced by X-rays.

Speaker 10 And this, of course, like alerted the public to the dangers of radiation and was like part of the whole like, oh, God, you know, oh, no. Right.

Speaker 10 But when Nipling read this paper, he was like, oh, my God, this, this is it. This is what I've been looking for.
Right. You know, I mean, paraphrasing.

Speaker 1 This is my flies.

Speaker 10 Yeah. And so he reached out to Mueller to be like, hey, do you think that I could use x-rays to make screw worms sterile? And Mueller was like, sure.
Like, I think that sounds great.

Speaker 1 I'm at it, bro. Yeah.

Speaker 10 And so Nipling borrowed an Army hospital x-ray unit to give it a go. And it worked.

Speaker 10 Like, not only were the males sterile, but the females that mated with them were also effectively made sterile because again, they only reproduce once.

Speaker 10 And later they switched from x-rays to like other methods of radiation, which gave more consistent results.

Speaker 10 But you know, once they tested this out in the lab, all they had left to do was actually, you know, see if it worked in real-world settings.

Speaker 10 And the first trials were carried out beginning in 1951 on Sanibel Island in Florida. And when it was 200 to 300 sterile flies were released each week.
How did they get so many flies, you might ask?

Speaker 10 They had to rear them in the lab. And because these live on, you know, like flesh, they used ground meat and blood.
Can you imagine just like the smell of that rearing?

Speaker 1 I feel like I read several papers where people were talking about the smell and like the process of finding the right.

Speaker 1 Actually, I read a really interesting one about the lures that they use now, like when in their monitoring programs, they have a loom. The lure is called swarm lure.
I think we're on version 4.

Speaker 1 And it's like this concoction that they made based on looking at what are all of the scents and the things that are emitted by the meats and the blood and the oviposition fluid and all of this other stuff to try and make a lure to attract them.

Speaker 1 It's like a lot.

Speaker 10 It's so gross. I love that though.

Speaker 1 I know.

Speaker 10 Yeah. I mean, that like, I don't, that seems to me like complete alchemy.
Like, that's magic to be able to be like, what are these compounds?

Speaker 1 Let's make this.

Speaker 1 There were so many people at U of I doing stuff like that, but for agricultural pests. Agricultural past.

Speaker 10 Yeah. Yeah.
It was just, it all sounds, it all is amazing to me. I love it.
Yeah.

Speaker 10 But anyway, so with the Sandibal Island, you know, real world experiment. The screw worm fly populations did drop over a couple of years, but they weren't eradicated.

Speaker 10 I mean, they dropped dramatically, but they weren't eradicated entirely. And that's probably because fertile female flies flew over from the mainland.

Speaker 10 But like, and what they really needed, I think what the U.S.

Speaker 10 government was looking for outside of the USDA, but like the, you know, the people who were providing the funding were like, we need 100% perfect eradication.

Speaker 1 It must be eradicated. Right, yeah.

Speaker 1 And so this is kind of...

Speaker 10 Yeah. And so they were like, we got to do something else.
Like, what else? What else? But this, so there was a kind of a lukewarm reception to these results. And so the U.S.

Speaker 10 government wasn't really keen on continuing trials. They were like, we tried it, but I'm not sure.

Speaker 10 But then there was an agricultural officer on the Dutch-controlled island of Curaçao who reached out to Nipling for help with their screw worm problem, which was huge.

Speaker 10 In 1954, Nippling was like, let's do this.

Speaker 10 So they dropped more sterile flies onto Curacao, and screw worms were eradicated within 14 weeks, which is four to five generations.

Speaker 1 14 weeks?

Speaker 10 Yeah.

Speaker 1 Eradicated. Eradicated.
Wow. I didn't realize it was that fast.
That's bananas. Fast.

Speaker 10 And so this, finally, this was like proof positive that Nippling's idea could work. And so the U.S.
government was like, okay. Sure.

Speaker 10 I guess. I guess.
And the dream of actual widespread screw worm eradication got a whole lot closer to reality.

Speaker 10 And it demonstrated that you could effectively control agricultural pests without the use of toxic substances like DDT.

Speaker 10 And actually in the like one of the last chapters of Silent Spring, Rachel Carson wrote about Nipling's work as like a hopeful path for the future.

Speaker 10 Like we can use biocontrol in a way that doesn't like destroy the environment. Yeah.

Speaker 10 Wow.

Speaker 10 It's very interesting. And so construction on bigger fly rearing facilities began, including one that was capable of producing 200 million flies a week.

Speaker 10 which was a feat that required 120 tons of meat, 114,000 liters of water, and 38,000 liters of blood each week. Would you like to know what kind of meat?

Speaker 1 I really got into the round of the early earlier. Okay.

Speaker 10 It included horse meat, whale meat, and ground up nutria.

Speaker 1 Those are all

Speaker 1 whale meat?

Speaker 10 Listen, I don't know. Later on, I don't think that this strategy, I think that they were like, this is not

Speaker 10 sustainable. We need to do something else.
And so they developed like a gelled substrate that was like dried cow blood, egg, milk substitute, and some formaldehyde to prevent it from spoiling.

Speaker 10 So they found something else that was less

Speaker 1 not using whale meat. Yeah.
Yeah.

Speaker 10 And so after they constructed these fly-rearing facilities, they were like, let's let's get this going.

Speaker 10 And so in the early 1960s, an eradication program began that targeted the entire southwestern U.S. By this point in time, screw room had been eradicated from Florida by the late 1950s.

Speaker 10 And so over that decade, over the 1960s, screw worm populations plummeted. Erin, if you will, play the clip titled Screw Worm 3.

Speaker 1 Okay.

Speaker 13 In this half of our century, man has conquered the atom, the frontiers of space,

Speaker 13 the depths of the ocean.

Speaker 13 Could not this advanced technology be applied to control pests with even greater effectiveness and safety.

Speaker 13 Within the last decade, radioactive cobalt-60 has been used to sterilize millions of pupae of the male screw worm fly, whose parasitic larvae, breeding in the flesh of cattle, deer, and other animals, posed a major problem to our livestock industry in the southern half of the nation.

Speaker 13 Once the pupae developed, huge numbers of sterile male flies were dropped over infested areas to mate with female flies,

Speaker 13 soon drastically reducing the population of a major threat in America.

Speaker 1 So

Speaker 1 that was them doing the irradiation, right? Yep, yeah. That was them dropping.

Speaker 10 Yeah, so that video is from the same clip from that I played at the start of this from the 1969 clip. And despite the haunting music, like the narration ends quite optimistically, right?

Speaker 10 Like this is the end of Squrooms. We're starting to see like we are conquering this.

Speaker 10 By the way, the video, I don't know if I mentioned this, but the video is titled Who Shall Reap.

Speaker 10 Yeah, it's kind of anyway. The whole video is

Speaker 10 great.

Speaker 1 It's so, this is a total side note, but it's so interesting to watch these old videos that are so like slow. Oh, yeah.
And the way that they're like, the narration is like this.

Speaker 1 And then, like, even the clips of everything. And I'm like, if this was today, it would be like, screw worm, beep, booty, break, boop, boop, like,

Speaker 1 1,000 cuts, like a million cuts. Yeah.

Speaker 1 You'd never actually see a fly because it would just be like, boop, boop, boop, boop, boop.

Speaker 1 Anyways.

Speaker 10 Education by a million cuts. It's true.

Speaker 1 But yeah, so,

Speaker 10 but this, I feel like the optimistic ending from that clip did play out for a while. Like that is the way that it was, it was looking, at least in the southwestern U.S.

Speaker 10 But the feeling was unfortunately short-lived because outbreaks of screw worm began popping up in 1972 to 1976 and then 1978 as well.

Speaker 10 And you know, what was going on, part of it was suitable conditions for screw worm development. So like it was a period of warmer and wet weather that provided just more habitat.

Speaker 10 And then another was reduced care for livestock. So, like, fewer and less frequent inspections.
Once you think screw worms are gone,

Speaker 10 one gets through, that one starts a huge problem. Yeah.

Speaker 1 You're not checking as much.

Speaker 10 Yeah. But these were, I think, relatively minor factors compared to the real reason for these outbreaks.
And that is that parasites don't respect arbitrary political boundaries.

Speaker 1 No, they don't.

Speaker 10 They don't. And so the eradication program, successful as they were, only focused on the U.S.
side of the border with Mexico.

Speaker 10 And since these flies can travel up to 180 miles or 290 kilometers, fertile flies could easily travel to treated areas. That's a huge flight range.
It's wild.

Speaker 1 Such a huge flight range. Yeah.

Speaker 10 And so the flight range, though, of these flies was not known when they started the eradication program. I think this was like one of the lessons learned right away.

Speaker 10 And so after the first of these bad outbreaks in 1972, which there was 95,000 cases were recorded, I'm sure that it was actually higher than that, the two governments, the U.S.

Speaker 10 and Mexico, signed the Mexico-United States Screw Worm Eradication Agreement. And about 10 years and a giant fly-rearing facility later, capable of producing 500 million sterile flies per week.

Speaker 1 Unbelievable.

Speaker 1 The numbers are unfathomable.

Speaker 10 Truly, truly. But things started to look pretty good.
Things were looking actually pretty great. And by 1991, all of the U.S.
and Mexico were declared free of screw worm.

Speaker 10 And there was a scary blip from like 1988 to 1992 when infected cattle were brought into Libya,

Speaker 10 infested with the New World screw worm. And then that made people super concerned that, like, hey, this is going to take over.
Like, this is going to spread everywhere.

Speaker 10 Africa, Middle East, Europe. And so a bunch of sterile flies were released.
And by June 1992, the region was declared screw worm-free.

Speaker 10 And this really demonstrated the importance of,

Speaker 10 well, first of all, it demonstrated the power of the sterile fly, the sterile insect technique, and the importance of thoroughly inspecting livestock for possible sides of infection.

Speaker 10 But that can be difficult to do. But do you know who's really good at it?

Speaker 1 Dogs. Dogs.
Yeah.

Speaker 10 There are dogs that have been trained for this purpose today. And I think the first screw worm detection dog was, there's a paper.
His name was Casador, which means hunter.

Speaker 10 And he was trained by researcher John Welch to work at quarantine and inspection stations. And he had a success rate of 99.7%.

Speaker 10 And the only time that he like didn't identify is when he had like some GI bug. And so he was sick and needed to rest.

Speaker 1 Oh, and they made him work even though he was sick.

Speaker 10 I don't think they realized. Yeah.
But it's like, it's so sweet. The paper,

Speaker 10 I have it. It'll be on our in our show notes or like in our in our on our website.
And it's, he's thanked in the acknowledgements.

Speaker 1 Oh, that's so cute.

Speaker 10 It is. And his leash and his ashes are in the National Agricultural Library in the screw worm unit.

Speaker 1 Wow. I know.

Speaker 1 Anyway.

Speaker 10 Isn't that, I just loved that.

Speaker 10 We'll put a picture of Kat. We'll try to find a picture of Kaz somewhere.
Yeah. There are lots of them.

Speaker 10 So anyway, over the 1990s and into the 2000s, eradication efforts in the Western Hemisphere continued into Central America and the Caribbean, and they were largely successful, at least for a time.

Speaker 10 But eradication has proved to be a moving target, and Screw Worm has re-emerged in areas where it was previously declared eradicated. And in light of that, I want to play just one more clip for you.

Speaker 10 So play Screw Worm 4.

Speaker 14 What lesson can we learn from the Screw Worm program?

Speaker 14 Well, to me,

Speaker 14 it is a remarkable program, and I sometimes wonder how it ever materialized in the first place, and however

Speaker 14 they were able to get this program underway.

Speaker 14 But it confirms something that I'm

Speaker 14 absolutely

Speaker 14 confident of

Speaker 14 and this is

Speaker 14 that if we're going to deal with major insect pest problems,

Speaker 14 we're going to have to deal with the

Speaker 14 from an area-wide standpoint.

Speaker 14 That we cannot deal with these pest problems by just trying to control them

Speaker 14 year after year on a farm-by-farm basis, just like we never would have controlled the screw worm that way. We will never control the bo weevil or

Speaker 14 the

Speaker 14 cornea worm or the

Speaker 14 cabbage loper or coddling moth or whatever. You'll never control these insects this way.

Speaker 14 I mean, you'll control them, but you will not reduce

Speaker 14 the threat.

Speaker 14 But there is a possibility that we can do the same thing for dozens of other insects.

Speaker 1 Oh, Aaron, I love that because that's like the conclusion at the end of my section as well. I know.

Speaker 10 It just, so like I said, that interview was recorded in January 2000 and the lesson is as relevant today as it was then.

Speaker 1 And extends so far beyond just insect and agricultural pests.

Speaker 10 Yes. It's Dr.

Speaker 1 Needle.

Speaker 10 Thank you. It's public health.
Yeah.

Speaker 1 Yeah.

Speaker 10 Like global, yeah, global health, all of that.

Speaker 10 And so, yeah, with that, Erin, I'll turn it over to you to tell me where, what the people really want to hear, which is where we are with Screw Worm today.

Speaker 1 Oh, let me tell you,

Speaker 1 it's not great.

Speaker 1 Yep, yeah.

Speaker 1 Every week, still to this day, for decades now, planes drop millions of sterilized insects, which are grown and irradiated. They use slightly different techniques now, in a lab in Panama.

Speaker 1 They've moved.

Speaker 1 The labs are no longer, the rearing facilities are no longer in the U.S., no longer in Mexico. They are in Panama.
And millions of sterilized insects are dropped across the Darien Gap

Speaker 1 and the very first part of Colombia in an attempt to keep screw worms out of Central and North America.

Speaker 1 And yet, despite all the success that you talked about, Erin,

Speaker 1 in 2016, I think is when the first like rumblings that things were not all perfect

Speaker 1 began. in modern most modern times, because there was an outbreak in Key West, Florida.

Speaker 10 That's right.

Speaker 1 It It was relatively quickly contained, but the deer population in Florida took a hit because of this.

Speaker 1 And despite the incredible successes of the program, the truth is that New World screw worms are still present.

Speaker 1 This fly is still present throughout nearly all of South America, as well as many islands in the Caribbean, including Cuba, Haiti, and the Dominican Republic.

Speaker 1 And so, since 2023, so in the last two years, cases have increased within like North and Central America from an average of about 25 cases per year to 6,500 in one year in 2023. Okay.

Speaker 1 And so since 2023, flies have been reported in Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Mexico, with more than 20,000 new outbreaks reported, like individual outbreaks, as of August 22nd, 2025, per the World Organization of Animal Health, or the WED.

Speaker 1 Okay.

Speaker 1 Most all of these outbreaks are in livestock animals. There are some cases in domestic animals.

Speaker 1 There have also been cases in humans.

Speaker 1 But some of these outbreaks have been hundreds, if not thousands, of animals infected. So, right now, on the APHIS website, which is the Animal and Plant Health Inspection Service,

Speaker 1 As of September 2nd, 2025,

Speaker 1 there are several outbreaks ongoing in Mexico that are of serious concern to the U.S. government, which has resulted in the U.S.
government shutting down all

Speaker 1 live cattle trade between Mexico and the U.S.

Speaker 1 There have been over 5,500 total cases in Mexico. Currently, as of September 2nd, 777 active cases

Speaker 1 and at least one confirmed case in a human in the U.S., which was a travel-associated case with someone traveling from El Salvador and coming back with an infection. They've recovered.

Speaker 1 In 2024, in Costa Rica, there were seven human cases that were reported, including one death. And in Nicaragua, there were 124 cases in humans in the last year.

Speaker 1 But this is not the case that, like, we as humans need to start panicking that we're all going to be infected with screw worm. That's not, that's not the situation here.

Speaker 1 But what this does show us is the fragility of our eradication efforts

Speaker 1 and the necessity of these one health approaches, and that they don't face the kind of budgetary cuts that we see currently playing out across every single health agency in the U.S.

Speaker 10 Budgetary and like intellectual cuts.

Speaker 1 Yes. Drake.
100%.

Speaker 10 I have a question about, so you, in terms of the numbers, we've talked about humans, we've talked about livestock, maybe a little bit like domestic animals. What about wildlife?

Speaker 1 Great question. What about wildlife? Certainly some of these infections are happening in wildlife, but we just don't have as good of numbers on wildlife populations.
Okay.

Speaker 1 But that is definitely a huge concern, right? Because not only is that like a potential reservoir,

Speaker 1 but it's also just, then we're affecting livestock populations and like the effects of this eradication program on benefiting the health of wildlife should not be understated as well, too. Yeah,

Speaker 1 um,

Speaker 1 yeah, so that's kind of like where we stand with like what's going on with current current outbreaks. Um, the

Speaker 1 live cattle market in the U.S.

Speaker 1 was valued in 2023 at three billion dollars per year, okay, and it's gone up since then.

Speaker 1 And

Speaker 1 the USDA

Speaker 1 says, estimates currently that an outbreak, like a true outbreak of screw worm in the U.S. could end up costing something like $10 billion in losses.

Speaker 10 So this is something that I kept coming across too, was the screw worm eradication program, which has cost money.

Speaker 1 Cost money. It costs $1.8 million a year.

Speaker 10 Yeah, it has saved so much in terms of revenue from livestock, people's livelihoods. And I think what is like, so it's like, okay, well, we can do this.
We did this here in the U.S.

Speaker 10 We did this in Mexico. We did this throughout a lot of Central America.
And in South America, it's like, well, they couldn't afford these programs, but they are losing money year after year.

Speaker 10 And so it's like, again, it comes back to this has, this is an area-wide program. I lack the words, the articulation needed to express this, but like, this should be a continental

Speaker 10 hemisphere-wide effort.

Speaker 1 100%, percent, Aaron. And so, right now, what the U.S.
is doing is going absolute ham. They are reopening facilities in Texas.
They are rebuilding a facility in Mexico.

Speaker 1 They're going to spend tens of millions of more dollars to start breeding flies in the U.S. and Mexico for sterile insect technique.

Speaker 1 It is going to take years, at least 18 months, is the current estimate, for these to happen and get up and running. This is essential that it happens right now.

Speaker 1 And they have this like five-point plan, which all sounds very much like war language.

Speaker 1 But they are taking this very seriously. And I think there was a paper from 2000, actually, that really exemplified what is the true kind of hero of the screw worm story.

Speaker 1 And that is that in order for the success that we have had thus far to happen,

Speaker 1 A ton of cooperative agreements had to exist between countries for this eradication program to take place and to be successful.

Speaker 1 Because yeah, flies don't give a crap about our national borders the same way that infectious diseases like COVID don't honor these artificial divisions. Right.

Speaker 1 Even though this program is currently kind of at risk, right, and we're having to re-up it, it was only possible in the first place because countries decided it was important enough to invest in and to work together despite the difficulties and the like financial agreements that had to be made to coordinate the implementation of this program.

Speaker 1 But they agreed it was important

Speaker 1 because they could make a lot more money.

Speaker 1 I mean, and because the livestock industry,

Speaker 1 yeah, the livestock industry and the funding around this were considered important enough. The absence of these screw worms in the U.S.

Speaker 1 is estimated at least at a minimum to be a $1.3 billion benefit every single year. So spending a few million dollars to keep this program running is nothing compared to that benefit.
Yeah.

Speaker 1 It would be great if we could recognize that this is also true for so many other things besides just screw worm.

Speaker 1 And yes, expanding this to be able to eradicate it throughout its entire range rather than just stopping at the border of Colombia would go a really long way to improving the lives of humans and livestock and wildlife across the entire Western Hemisphere.

Speaker 1 Yep.

Speaker 1 Uh-huh.

Speaker 1 And it is also possible that this could happen for old world screw worm. They have very similar meeting habits.

Speaker 1 So they could also benefit from sterile insect technique programs, but there just hasn't been as much of this collective agreement, infrastructure buildup, and the money up front to be able to do this where old world screw worm, that's really hard for me to say, is endemic.

Speaker 1 And so the programs that have tried to get up and running there have not been as successful.

Speaker 1 There's a lot of interest too in like creating like newer techniques to make this even more effective and even more cost-saving, like doing transgenic flies so that you're only really rearing male flies.

Speaker 1 Because right now you're rearing indiscriminately female and male flies.

Speaker 1 So if you could kind of whittle down the female population so that you're only releasing male flies, you're kind of doubling your efforts, but at a lower cost.

Speaker 1 But, like, all

Speaker 1 of that is amazing. This is an amazing program.
It is incredible.

Speaker 1 Let us apply this success to other facets of public health.

Speaker 10 Use it as a framework. Like, this is, I mean, and it is, like, it's it is, but it's also not.

Speaker 1 Yeah.

Speaker 1 And that screw worm, baby.

Speaker 1 Oh, wow.

Speaker 1 What a fascinating thing, though. Like, also, just the like

Speaker 1 the entomology of it all. I love

Speaker 10 the entomology.

Speaker 10 I just also, I love, I think this is when I was like, oh, I could spend weeks just digging around on the USDA, like the National Agricultural Library website, and then the archives, the internet archive.

Speaker 10 Like, I was having a blast looking through these oral histories and the transcripts. And I'm like, there are more that aren't digitized.
I want them.

Speaker 10 I reached out to a librarian and was like, can you help me find this? And they did. And I'm just like, I love library.
I love libraries. I love librarians.

Speaker 1 It's,

Speaker 10 and also, I think I had no concept.

Speaker 10 how huge this program was because you you can't find a lot of other agricultural, well, maybe agricultural pest videos, but like other disease videos from the 1950s and 60s and so on, not so much.

Speaker 10 Like this is a huge effort and it was a huge success story and it can still be.

Speaker 1 Yeah.

Speaker 1 It will be. I think it will be successful.
The funding is going there. It's happening.
Yeah.

Speaker 1 But yeah, can it go further? That would be cool. That would be cool.

Speaker 10 Should we tell the people where they can find more information? We should.

Speaker 1 We should.

Speaker 1 I

Speaker 10 have linked to all of those videos.

Speaker 1 Love it.

Speaker 10 I have a ton of sources, but I'm going to shout out two in particular. So, one was the website,

Speaker 10 the Stop Screw Worms.

Speaker 10 It's an online, like, digital collection. So, it's selections from the Screw Worm Eradication Collection on the National Agricultural Library, USDA, websites.
Very cool. And then, also, there was

Speaker 10 a couple of fun chapters in a book, a popular book published in 1984 called the Dragon Hunters by F. Graham.
And it was these two chapters that I read focused on screw worm and screw worm eradication.

Speaker 1 Love it.

Speaker 1 I had a bunch of papers.

Speaker 1 I don't even know, Erin.

Speaker 1 The one that I mentioned already that I did really enjoy was by Wiss

Speaker 1 from 2000 called Screw Worm Eradication in the Americas. That focused a lot on like the success of these collective agreements and things like that.

Speaker 1 There was also a paper from 2017 that was review of research advances in the screwworm eradication program over the past 25 years. That was really interesting.

Speaker 1 And then a couple of papers that are like quite old from like the 80s and 90s about the screw worm. behavior and biology and things like that.

Speaker 1 And then I also have links to the USDA website where they have their New World Screw Worm Domestic Readiness and Response Policy Initiative document, which is really interesting to read through.

Speaker 1 And then also the updates, if you would like them, because I'm sure the numbers will be different by the time that this episode comes out.

Speaker 1 But on the APHIS website, you can find those like updated data on what the outbreaks look like in Mexico, what other cases have been reported and things like that.

Speaker 1 You can find it all on our website, thispodcast, willkillyou.com.

Speaker 10 Thank you to Blood Mobile for providing the music for this episode and all of our episodes.

Speaker 1 Thank you to Liana and Tom and Pete and Brent and Jessica and everyone else at Exactly Right who makes all of this possible.

Speaker 10 And to you listeners who also make this possible, who, you know, let us keep doing this and our patrons you know a big you know thank you shout out to you as well your support means the world to us we love you yeah that's it

Speaker 1 well until next time wash your hands you filthy animals

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