The New World Screwworm has been in the news lately because it turned up in southern Texas in early June. These parasites are endemic to central and south America these days, but they were once present in the southern United States but were eradicated in the mid 1960s.
The parasite is actually a fly whose larvae burrow into and feed on the living flesh of warm-blooded animals, cattle primarily in the Texas cases but also sheep. Unchecked, screwworm outbreaks can be economically devastating for cattle and other livestock farmers.
There was actually a localized outbreak of New World Screwworms in the Florida Keys in 2016 but it was contained using what’s called the Sterile Insect Technique where millions of sterile flies are released with the goal of them mating with wild females which crash the population.
Because a screwworm outbreak is potentially a big deal for the entire United States, including here in Florida, we talk with an expert from University of Florida.
Guest:
Dr. Juan M. Campos Krauer, Clinical Assistant Professor in the Department of Large Animal Clinical Sciences & Department of Wildlife Ecology and Conservation at University of Florida
Click here to visit www.screwworm.gov, or here to explore the Florida Department of Agriculture's information page.
WGCU is your trusted source for news and information in Southwest Florida. We are a nonprofit public service, and your support is more critical than ever. Keep public media strong and donate now. Thank you.
Transcript created with Copilot. Please forgive any spelling errors or mistranslations.
Mike Kiniry
This is Gulf Coast Life. I'm Mike Kiniry. Thanks for joining us. The New World screwworm has been in the news lately because it turned up in southern Texas in early June. These parasites are endemic to Central and South America these days. They were once present in the southern United States, but were eradicated in the mid-1960s. The parasite is actually a fly whose larvae burrow into and feed on the living flesh of warm-blooded animals, cattle primarily in the Texas cases. Unchecked, screwworm outbreaks can be economically devastating for cattle and other livestock farmers. There was actually a localized outbreak of New World screwworms in the Florida Keys in 2016, but it was contained using what's called the sterile insect technique, where millions of sterile flies are released with the goal of them mating with wild females, which crash the population. because a screwworm outbreak is potentially a big deal for the entire United States, including here in Florida. I'm joined today by Dr. Juan Campos-Crower. He's Clinical Assistant Professor in the Department of Large Animal Clinical Sciences and Department of Wildlife Ecology and Conservation at University of Florida. Dr. Campos-Crower, welcome to the show.
Dr. Juan Campos Krauer
It's a pleasure. Thank you very much for inviting me.
Mike Kiniry
So for starters, can you just tell us a little bit about yourself and your background?
Dr. Juan Campos Krauer
Yes, as you said, I'm a veterinarian here in the University of Florida. I specialize and mostly work with white-tailed deer or deer in general. But I also have a lot of experience with wildlife. I have worked with hogs, peccaries, tapirs, mostly animals from South America. And lots of experience also with cattle ranching and everything related, small remnants. I did a lot of work in South America, so I actually have a lot of experience with this flight that you have been talking about.
Mike Kiniry
I saw on your CV that you did a degree in Paraguay. Are you from there?
Dr. Juan Campos Krauer
Yes, I grew up in Paraguay. I am from Paraguay, yeah.
Mike Kiniry
And you were a Fulbright scholar in 2004?
Dr. Juan Campos Krauer
Fulbright Scholarship, and that's when I was able to do my PhD in Kansas State University.
Mike Kiniry
Interesting. So how long have you been at UF?
Dr. Juan Campos Krauer
I have been, right now, it's almost 10 years.
Mike Kiniry
So you're an extension veterinarian with UF's Servaday Health Research Initiative. I saw that on your website. Can you explain what that is and does? I want to talk a little bit about that and deer before we get to screwworm, because there's some lessons to be learned, I think.
Dr. Juan Campos Krauer
Oh, yes, So yes, my position is clinical assistant position, but I also work as an extensionist and researcher in the Survey Health Research Initiative. So the Survey Health Research Initiative is a program that started because, as maybe you don't know, there's lots of deer farms here in Florida, and they were really concerned about many of their animals dying. because of an hemorrhagic disease. It's a virus. It's called episodic hemorrhagic disease. You've probably heard it or seen pictures of these deer going to the water and dying in the water in many parts of the United States. And there was a big problem here in Florida. And that's how this program started. The main objective was to better understand this disease and be able to mitigate, find ways to manage the animals. And also one of our big success, I think, is that through the work we have been doing, we were able to get private companies to work together with us and produce a vaccine. So right now there's a vaccine that can be used that prevents that very deadly disease in white-tailed deer. And we are very concerned in terms, especially myself, being a person that worked with wildlife and that has experience with screwworms is that wildlife is going to be a big component if we ever get this screwworm back, which I hope we never do.
Mike Kiniry
The Florida deer farms, more than 400 that you mentioned, is partly why I brought that up, because I grew up in Florida and I've been talking on the radio about interesting wildlife stuff for a long time, and that was a new concept to me. These aren't farms like Old MacDonald. These are farms like managed areas where people can hunt deer or just have deer live, right?
Dr. Juan Campos Krauer
There's two ways, yes. These are deer that are grown or produced in high fences. So they have pens. That's where these animals are. They're reproduced. Now, they can be small or they can be very big. They're all depending. There's a big variety. But the thing is, many times people think about deer farming as an industry where there's these very tame deer in these pens and then people send them out for hunting. because most, the big majority of the produced bucks in these farms are for trophy hunting. So these deer are bred and reproduced in a way that they're still very much super wild. That's why it's so difficult to work with them. And these animals are sold and moved to a big preserve where they can be hunted for trophy hunting, for example.
Mike Kiniry
Which I presume would be then part of sort of the nature part of the tourism industry or a slice of it.
Dr. Juan Campos Krauer
Absolutely. That's why Florida is so big, because many people come with a family, they come to the park, they come to the beach, but also there's a big opportunity to go hunting and many different species because that's an advantage that Florida has is that you can also raise not just whitetail, but many other deer species as well here in Florida. So that's a big advantage in market for this industry.
Mike Kiniry
Interesting. Are deer in managed areas like that more susceptible to, say, screwworms if they were to show up because they're less attended to or focused on than cattle would be?
Dr. Juan Campos Krauer
It will really depend, and they're different. in terms of their behavior. So deer are a lot more sensitive to flies or other things. They don't get... Let me see how I can explain this. The species are different, right? So deer are a lot more delicate. So it can be a problem if these deers are being captive raised. There's 2 advantages. One, you can see the animals that are right there. And second, you have the chance of treating them. You can use darts or you can have facilities to bring them in, but you can treat them. It will be very different from a deer that's out in a preserve, big preserve, running completely free, or a completely wild deer. Those will be very challenging to treat or even to see, because that's one of the things that's always tricky with wildlife, is that most of the wildlife will never show their weakness. even if they're super, very, very sick, if humans come by or they notice that there's a predator or humans, they will always show themselves that they're perfectly healthy and strong. They'll never show weakness. So that's why, especially in case of screw up, it can be, it will probably be challenging to identify animals that are very sick, unless they're at the point where they're really sick. And so A little bit different. We will have to see how exactly that's going to work out. But I assume that deer will probably be less likely to get infected unless they have a lesion. And that also will depend if they're bugs and they're growing. They're antlers, for example. Antlers can bleed very easily. And this screwworm, the fly, is searched for those little lesions, blood, cuts, things like that to lay their eggs. So it will all depend on the season, the category of the animal, and the situation and where they're being raised.
Mike Kiniry
Fascinating. So explain, you know, describe what a screwworm is for our listeners.
Dr. Juan Campos Krauer
A screwworm is a fly that's native for most of the Americas, South, Central America, southern United States. It was around for a long time until it was eradicated in the southern United States. The big difference between this fly and any other fly that lays eggs and they produce larvae or maggots is that most of the other flies will lay their eggs on rotting or dead things. for these eggs to hatch, the larva to come in and start feeding on that. The big difference with the screwworm is that the screwworm doesn't feed on dead animals or things. It feeds on live animals, generally warm blood animals, tissue. That's the big thing. And the other thing is also, you have to understand this is not a pathogen, it's not a disease, it's a parasite. So this fly tends to search for animals. It's always searching for animals that have small lesions, cut bruises, and that attracts this fly, and that's where it's going to lay its egg. And those eggs will hatch into little larvae, and those maggots will go in, and they start feeding voraciously on the tissue of a living animal and creature.
Mike Kiniry
So they can, if left unchecked, they could kill a cow that they got into.
Dr. Juan Campos Krauer
At the point, yes. So generally, this fly has around, and I'm not an entomologist, so I could make some mistakes. I want to clarify that. But generally, it's not that the cycle for this fly is 21 days. Generally, from egg to development, it's 21 days. So 3 weeks. When the female fly produces eggs and they lay them on the lesion or on an area that has a little bit of blood on an animal, these eggs will hatch in a couple, generally in a couple hours, up to 24 hours, and they'll start growing and feeding, feeding, feeding, feeding for around 5 to 7 days. Then these eggs will jump out once they're fully developed, they will jump out of that lesion, go in the ground, pulpate, and then for another, almost another week, and then the mature fly comes out and lives again another week or 10 days trying to reproduce and lay more eggs. I just wanted to kind of show the cycle because it's really important. The other big difference between this fly and other flies is that these larvas will feed on that animal and grow in five to seven days. So depending on the amount of eggs that hatch and amount of larvas, that wound can grow from day one being 1/4 inch, day two being 5 inches, day three being 6, 7 inches. And that's an area that all the muscle, the tissues and everything was already consumed. So imagine, it's very, very bad. At the same time, if there are more screwworm flies flying around, they smell because that doesn't smell very nice because it's all this tissue decaying, all this liquid fluids, blood. More flies lay their eggs. So you have larvae, some that are finishing their stage. Some that are in half, and some new eggs, so it's something that could keep growing, so... No, you're absolutely right. If not treated completely, the animal can be killed. These larvae will bore into the soft tissue. Sometimes they'll go through the brain. Sometimes they'll go the mouth. They'll eat up the tongue. And they're really, they're very, very aggressive eaters. They can even go into the abdominal cavity and start feeding on organs, the chest. So what starts with a little tiny lesion and a couple eggs can get very bad fast.
Mike Kiniry
So they were eradicated in the mid-60s in part or maybe primarily using sterilized flies released into the wild. Is that still how they're controlled today?
Dr. Juan Campos Krauer
Yes, So They were eradicated in the late 60s from the United States. Florida eradicated its population earlier than that, I think it was in the mid 50s, and then it took a couple years to eradicate it completely from the United States. Then the objective was, okay, we have cleared the United States. Where can it come from? Most likely Mexico, right? So then there was the project continue and they started an eradication program to eradicate the flight completely from Mexico. They went down to Central America as well. And in the 90s, they reached Panama and all the north part, it was eradicated. That's what changed in 2022, I believe, if I'm remembering correctly. There was a couple outbreaks in Panama, then it moved to Costa Rica, and it started moving up to southern Mexico. I think in 2004, 2005, it started coming up, and now we have some cases in southern Texas. So yes, it's the same method. The unique characteristic that this fly has that it's an advantage to be able to eradicate them is that the female fly, one comes out of the poopy and it's an adult animal, animal insect, sorry, it will go out and it will just copulate with one male in its life. And then it will search a place where to lay those eggs. So it doesn't search for multiple male, just one male. So that's a big advantage. And that's why this method works, because what happens is that these big labs are made where they can reproduce millions of male flies, treat them with gamma ray to make them sterile, and then fly with planes or release them in an area where there's an outbreak. And what happens is that we know that the female flies, the wild ones, will only reproduce with one male. And what happens? It reproduces with a sterile male. She will still produce eggs, so she thinks she's perfectly fine. She'll lay those eggs, but those eggs are infertile and they will not hatch. And that's how you break the cycle and that's how you can slowly, you know, exterminate and reduce the population until it's vans.
Mike Kiniry
This is Gulf Coast Life. Our guest today is Dr. Juan Campos Crower. He's Clinical Assistant Professor in the Department of Large Animal Clinical Sciences and Department of Wildlife Ecology and Conservation at University of Florida. The New World screwworm crossed the southern border in early June. There have currently been 32 confirmed cases, mostly in Texas, but at least one in New Mexico, mostly in cattle, but also some sheep. The parasite has been eradicated in the U.S. since 1966, although there was a localized outbreak among wildlife, mostly deer, in the Florida Keys about a decade ago that was brought under control after about six months. Today we're getting a lesson on these parasites that are endemic to South and Central America but are making their way north once again. They are potentially economically devastating if a widespread outbreak were to occur. We don't have a bunch of time, but can you just tell us a little bit about the 26 outbreak down in the Keys? Was that mostly in Key Deer?
Dr. Juan Campos Krauer
Yeah, there was an outbreak that, if I remember correctly, occurred in 2016, I believe. Yes, it was only in the Key. That was a big advantage that it was Perfect, because Eccasia has one road coming in and out, right? So it was easy to control, to check. And our Department of Agriculture, Florida Department of Ag did an excellent job coordination with Fish and Wildlife to be able to control and not have any infected animals come out. Because as you know, this fly will also affect pets. It can affect dogs. It can affect many other, any warb animal it can be affected by this. So there was a big concern that anything can move out. So yes, it only affected the key. They were able to keep it there. It killed many, many key deer, which is in a species of deer that's in danger. There's only around 8, an estimation about around 800 left in the keys. They're really tiny, really beautiful. deer, and around 200 died because of this infection until they were able to manage it and reintroduce the sterile flies in the outbreak.
Mike Kiniry
How concerned are Florida cattle farmers and other livestock farmers, and I guess deer farmers, about these flies potentially showing up in Florida right now?
Dr. Juan Campos Krauer
Everybody is always worried when you're going to be dealing with something that you don't have experience. Probably the older producers had a little bit of experience before it was gone, but newer producers have never seen these cases, and it's always challenging. But I can tell you that we have a group here in the University of Florida. We're working in coordination with the Department of Agriculture. We're working in coordination with Fish and Wildlife to be able to prevent this fly from coming in. And if it comes in, there are also ways to treat it. So that's the other thing. It's not the end of the world. There are treatments to prevent the infection and also to cure the infection. The always the tricky part will always be wildlife because as you can't really hold and catch all the wildlife. We never know exactly where they are. So they can be a little bit more tricky. But for producers, I'd say it's something to look for in terms of work with your veterinarian, make sure that he's aware of the new products that are out that have just been approved for use in case there's an outbreak, but we're working really hard to try to prevent this fly from coming into Florida.
Mike Kiniry
Is the supply of sterile flies adequate? I learned in researching for this that after the eradication in the United States, we don't really produce them domestically anymore. From what you know, are they able to make enough flies to keep up if things were to spread here?
Dr. Juan Campos Krauer
I don't know exactly at this moment, but I do know that Texas has a brand new lab and they're ramping up production. They're ramping up production super fast, so they're working really hard to ramp up and make sure that they have enough flats. In the past, because the fly wasn't present in the United States anymore, it wasn't present in Mexico, Central America, there was only one lab that was still producing these flies and it was located in Panama. So I know that now they're working and they have labs in Texas and I know they're working hard to get as many flies as possible.
Mike Kiniry
One thing I learned in reading up for this is that the first sterile fly production facility was built in Sebring, Florida in 1958. I just thought that was interesting for Southwest Floridians.
Dr. Juan Campos Krauer
Yes, It started very early. Here in Florida, it started very early. That's why I say there's still, I still know some producers that are old enough that remember the time before the screwworm was eradicated. And they always would say that it was hard times. There was not as many products as we have now to treat those parasites. But Yes, a big part of it was here in Florida.
Mike Kiniry
And just to be clear, these are potentially something that if you had an open wound as a human and didn't really pay close attention, they could infect you or lay eggs on you. But it's really, really a very, very low risk for humans unless they aren't paying attention.
Dr. Juan Campos Krauer
Yes, like I said, any warm animal, a warm blood animal can be affected. Humans were warm animals. If If a person has adhesion, and you may hear in those, in cases, for example, of people that fall or have accidents or get lost like in the jungle in Central South America, that they have lesions or cuts and then they can get infected with worms. Yes, that's the case. If you have a lesion, you may get infected if these flies are around. But I mean, in a more urban area where you have other people and where you have access to health care, it should not be a problem at all. Unless you're stranded somewhere, in a very bad situation, that could be a different story.
Mike Kiniry
If you see an animal out in the wild that has the kinds of wounds that you've been describing, who should you report it to?
Dr. Juan Campos Krauer
Yes, so One thing I encourage everybody, report, report. If you see anything strange, and talking about wildlife, and I'm so glad you brought this up, one of the things that we will see, if it ever comes back to Florida, hopefully not, and wildlife is affected, one of the things that wildlife does is they will change their behavior. So if a deer, for example, and one of the animals that I'm worried that it's feral hogs, for example, is affected, it's likely that this animal will change its behavior. So if you happen to see, let's say the fly is around, there have been some cases in Florida, which hopefully not ever, and you see a deer just coming out and going in circles, acting strange, Maybe it seems it looks like it has a hump or something in his back or anything strange. It's always important to reach out to the Fish and Wildlife to let them know so that they can come and take and take a look and see if it's a screw one case or not. You can also one if you're interested in getting more information, a really nice web page where you can go is the www. screwworm.gov. You will have you will find lots of information there. That's where including all the United States everywhere. And you can also go to the Florida Department of Agriculture where you can find just type down screwworm. You'll find every all the updates for veterinarians. It's important that they go there because there are new products. There are there are now available. that will work against screw one. And it's important for them just to be prepared and have those products in their head in case they need to use them in the future. And that's for small animals, large animals, and horses.
Mike Kiniry
That is unfortunately all the time we have. I want to thank my guest, Dr. Juan Campos-Crower, is Clinical Assistant Professor in the Department of Large Animal Clinical Sciences and the Department of Wildlife Ecology and Conservation at University of Florida. Thank you so much for your time, Dr. Campos-Crower. I really appreciate it.
Dr. Juan Campos Krauer
You're welcome. It's been a pleasure. And anytime, if you have any questions, please just reach out.
Transcript created with Copilot. Please forgive any spelling errors or mistranslations.