DairyVoice Podcast
DairyVoice Podcast
What Farmer’s Need to Know About The New World Screwworm
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In this episode of DairyVoice, host Connie Kuber with Sealpro Silage Barrier Films interviews Dr. Jamie Jonker, Chief Science Officer and Vice President of Sustainability & Scientific Affairs with the National Milk Producers Federation. They discussed the New World Screwworm and how serious of a threat it is.
Dr. Jonker dives in to many aspects of the Screwworm, including behavior in real-world situations, what environmental conditions are good - and bad - for the Screwworm. Connie Kuber talks with Dr. Jonker about what dairy production systems are most vulnerable, what diagnostic tools are available to dairy farmers being affected and many other aspects of this pest that DairyBusiness News readers have been asking for. The podcast has tons of information and where farmers can go to find out more information.
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SPEAKER_06Good morning, good afternoon, and good evening. Welcome to the Dairy Voice Podcast by Dairy Business News. I'm your host, Connie Cooper, with Seal Pro Stilage Barrier Films by Connor AgriScience. Thanks for joining us today. Please like, subscribe, and share this podcast with your friends. So unless you've lived under a rock this past year, you've heard of New World Screw Worm. My guest today is Dr. Jamie Jonker, who is the Chief Science Officer with National Milk Producers Federation. And he's going to inform us on what's the latest about this situation that our dairy and beef industry are facing. But first, Dr. Jonker, could you give us some background on who you are and where you've been?
SPEAKER_02Great. And uh thanks for the opportunity to be here, Connie. I am Jamie Jonker, the Chief Science Officer with the National Milk Producers Federation. For those not familiar, the National Milk Producers Federation is a trade association located in Arlington, Virginia, and our members are dairy cooperatives and they're dairy farmer owners. So National Milk represents their interests in the federal arena. I work within our regulatory group focusing on on-farm activities that includes uh things including animal health and welfare, uh, antimicrobial use, and and even sustainability issues. I've been with uh the federation for 21 years now. Prior to that, I spent some time at the National Academy of Sciences, and before that, even spent uh one year working on the House Committee on Agriculture in the House of Representatives.
SPEAKER_06Okay, very good. Very good. Well, thank you. We're we're looking forward to hearing what you have to say about this ever-evolving situation, it seems that we have.
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SPEAKER_03If you show that you're invested in this farm and that you care about those things like consistency and reaching production goals and reaching reproduction goals, and then invest in your employees, you will have a more productive, a more efficient, more profitable farm.
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SPEAKER_06So let's just start right out. How serious is the threat at this moment?
SPEAKER_02I would say that I would call it a tempered threat. Um, right now it's in the uh border area in Texas and Mexico. It is an increasing geography, but it has the potential to be the most consequential uh livestock pest that uh we faced in the U.S. in a long time, and probably the longest since uh we last had real large infestations. New World Screwworm was eliminated from the U.S. uh in the 1960s. There have been a few incursions since then. And the reason that it is so distinct from other types of uh pests and maggots that can be in cattle is that instead of feeding on dead tissue, the new world screwworm larvae feed on living tissue.
SPEAKER_06Okay, all right. So that's the concern about the productivity and uh health of these animals. Yes. How does this new world screw worm behave? The environmental conditions, what is it? Does it like humidity? Does it like heat?
SPEAKER_02Yeah, so the the female flies are attracted to wounds on the animal, and in some cases, natural body openings like the navel of a newborn calf. The female can lay hundreds of eggs in a in an individual wound and can uh lay eggs multiple times. Importantly, they only breed once, and we'll get to that probably in some later questions and how we work on control elimination. Uh, the flies do like warm temperatures, high humidity, things that create uh an opportunity for them to uh breed and spread. And so we are entering that time of year when we are in the high heat of summer where you have an increased risk. The fly itself is very temperature sensitive, and you get a number of days below about 20 or so degrees Fahrenheit, and it will kill the flies. And so there is a seasonal component to this, but there certainly are places, including some of the places where it has been detected in the US to date, where it likely could overwinter, depending upon how mild the winter might be in those areas.
SPEAKER_06Right. Like out here in California with our dry heat, is it is the dryness something that helps us?
SPEAKER_02It may have a moderate impact, but as we've seen in some of the places where there currently have been animals found with New World Screwworm infestations in Texas, it can also be in areas that uh are very hot but also very dry. Okay. So while it may prefer a more humid environment, just because it's a dry heat doesn't mean that uh there is no risk of New World Screwworm flies.
SPEAKER_06Say that this gets into a herd, how quickly does it spread?
SPEAKER_02So the spread depends upon a couple of things: the number of female flies that might be in that area, and really how often the animals are inspected for potential infestations. You know, with our dairy animals, certainly within our milking stream, they're seen multiple times per day, not necessarily all over their body, but you have eyes on them quite often. If we're looking at things like cow calves out on pasture, particularly those that require multiple acres for production, where they might be seen every few days to every few weeks, the risk is much higher.
SPEAKER_06On our dairies, then, I mean, we have a lot of different ways that we handle cattle, a lot of different systems. Which ones are more vulnerable, which ones are not as vulnerable?
SPEAKER_02Yeah, what I would say here is the risk is not necessarily tied to things like herd size or housing style. It's really how often they are seeing the animals and if they are in a place that has an infestation outbreak. But we do have populations that perhaps are more vulnerable within our dairy cattle population. Newborn calves, for example, uh, with infestations in the navels for places that are castrating the male calves for steers, also similar issues with uh infestations in castration areas. Fresh cows have vulnerabilities in the vulva, routine operations that happen that can lead to potential wounds, things like disbudding or even placing a tag in an animal. If they're in an area where there is a much higher risk for new world uh screwworm flies to lay eggs, can be much more vulnerable. And then obviously, animals with any injury. And the thing with injury here or a wound is that the new world screwworm fly does not need a large entryway to lay its eggs, it can lay its eggs in something as small as a tick bite. And so when you think about that, the ability of an animal to just get a scratch in its daily environment presents a risk.
SPEAKER_06So I would think then in addition to looking around at your uh inspecting your animals, you're gonna be want to inspect your facilities so that you're not you can reduce those risks.
SPEAKER_02You know, certainly from a general animal welfare perspective, you always want to wanna be looking around your facility to uh make sure that you are minimizing the risk of uh of injuries. And so this is just a reinforcement of that, particularly for those folks that are much closer to the to the new world screwworm today.
SPEAKER_06Right. We talked about how it this fly could overwinter, but how long can the larvae survive under farm conditions?
SPEAKER_02The new world screwworm fly has about a 21-day life cycle. What happens is once the the female uh has mated, it lays its uh eggs in a host animal. The eggs hatch within 12 to 24 hours. The larval stage, which is when they are actually consuming live flesh in the animal, is around five to seven days. Uh, then the larvae transition to the pupa stage, which is about another week, and then they are adult flies, and then it takes a few days to find a mate, and that gets you about a three-week cycle. And so it's a very short cycle. As I mentioned earlier, the uh female flies only mate once. They can lay eggs uh multiple times, two to three hundred eggs at a time, up to uh two to three thousand, uh, depending upon their own individual productivity. And so it's a very fast life cycle, and the flies can infest multiple animals or multiple sites on an individual animal if that animal has multiple points of entry.
SPEAKER_06How big are these flies compared to like other flies that we've seen in our cattle?
SPEAKER_02They're uh similar in size to like a house fly. The the larvae can be around an inch or so. One of the things when when you look at the flies of the larvae, it's very hard to distinguish from other flies in larvae. And so just a visual inspection from an untrained person, it's very difficult to distinguish. And so we highly encourage if anyone finds something that they believe is has a potential to be new world screwworm, that they contact their veterinarian or a state animal health official because it's very important that they have uh an official diagnosis as to whether or not it's new world screwworm, because there are important implications about how the state and federal governments will uh respond when they find a world screwworm infested animal.
SPEAKER_06Mm-hmm. Mm-hmm. Okay, so as we're inspecting these animals, are there are there signs that we're missing?
SPEAKER_02Places where you look and pay particular attention, navel on newborn calves, uh, for uh bull for male calves that are castrated around the castration site, tea injuries, vulvas after calving. A place that people might not think about about has a potential are uh foot lesions or hairy heel warts in between cow's hooves. I've mentioned before about ear tagging uh sites and uh disbutting sites and surgical wounds. So, you know, any animal that requires uh even minor surgery are places to pay particular attention to.
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SPEAKER_02Doing that, you know, daily inspection. And if you see something that looks worse than you think it should, or certainly if you start seeing activity from larvae, that's a time when you need to uh contact your veterinarian or state animal health official, uh, or even the USDA area veterinarian in charge because it's important to find out whether or not it truly is New World Screwworm.
SPEAKER_06Okay, and we're and we're inspecting these animals and area on a daily basis.
SPEAKER_02We highly recommend across all age classes, if you're in an area of uh high risk, uh, to do that daily observation, paying particular attention to those high-risk animals like newborn calves and research and fresh animals.
SPEAKER_06Right, right. Which on the beef side of things makes it really hard to keep up with this. They don't have the benefit of having those inspections every day like we would on the dairy.
SPEAKER_02They may not have those routine touch points that we have every day. And of course, I know that the Texas Animal Health Commission has been doing a lot of uh outreach to farmers and ranchers in the counties that have uh in fact infested animals to uh help bring them the information about the importance of really getting their eyes on their animals to make sure that they can see and detect if there is a potential infestation.
SPEAKER_06So, besides just finding it on the animals, are there other tools that we can use to diagnose this or to tell if we've got a situation that could be happening?
SPEAKER_02USDA working working with the state of Texas is has fly traps out to collect flies. And I think to date they've examined, you know, probably over 100,000 flies. And so far they've not caught any in the traps, which which means that there's probably only a small population in those areas. It's still concerning that the geography has become you know relatively large in Texas already. So far, I would say we're having relatively, I think, good luck in terms of of the use of those. And then it's you know looking with your eyes, and if you see something, it's working with your veterinarian, the state animal health official, or or the USDA area veterinarian in charge. Because ultimately, anything that they think might be New World Schoolworm has to go through official diagnostics related to the USDA National Animal Veterinary Services Laboratory in Ames, Iowa. Okay they have set up in Texas a secondary lab where they are able to do that official diagnostics and confirmation as well. And that that's uh uh running in Texas in an area where there are have been new world screwworm cases found in domestic livestock.
SPEAKER_06And that's looking at the larvae or the pupa and the flies themselves, right?
SPEAKER_02Yes, it is.
SPEAKER_06So what's been the success?
SPEAKER_02What's the what what works? You know, the way that this was eliminated from the US uh in the 1960s and and actually eliminated um all the way down to Panama into what's called the Darien Gap, which is a uh forested region at the uh Panama Columbia interface, uh, has been the uh sterile fly technique. And so what that does is uh flies are produced and and then they are go through an irradiation process that makes the male flies sterile. Okay. And the female flies only mate once. So if you have an area where you have New World Screwworm flies reproducing, you just flood that area with as many sterile male flies as possible, and you work to have them be what the female flies mate with. And that was very successful. That is the the major way that it was eliminated from the US and all the way down to Panama. That the elimination in Panama was in the early 2000s. Now, of course, we've seen it move back up from Panama through Central America into Mexico and into the US, here with that first case at the beginning of June. But it is still probably right now the most tested and true way of eliminating. That being said, USDA has funded a number of projects for over $100 million in their uh grand New World Screwworm challenge to look at next generation ways that can assist with eliminating New World Screwworm first from the US and then eventually moving it back all the way down to that uh Darien gap in Panama.
SPEAKER_06So if I if I'm using that system on my farm or my ranch, where do I even get those?
SPEAKER_02So those are distributed by the federal government. So they will not send Jew flies, they actually airdrop flies uh in areas, and then they also have uh on-the-ground dispersal systems, and they are distributed based upon the uh risk analysis that USDA conducts based upon where they're finding infested animals. And right now there's 100 million sterile flies that are produced weekly at a facility in Panama within the last uh two weeks. USDA working with the Mexican government has opened a facility in Mexico that is starting to produce uh sterile flies, and that one full capacity later this year will be producing about another 100 million sterile flies a week. And then in April, USDA announced that they will be building a production facility on a military base in Texas to open sometime mid-year to third quarter next year. That one would be producing at full capacity 300 million flies per week. And that half a billion flies per week is about the production that was occurring in the 1960s when it was eliminated from the US.
SPEAKER_06Let's back up just a minute to what the ramifications of this of a fly infestation. If I have a herd and it gets infested, what's going to happen? Are we talking about dropping milk production? Are we talking about losing cattle? What are we talking about?
SPEAKER_02The thing about New World screwworm flies and their impacts on animal are it's it's on the individual animal and not specifically across an entire herd. Unlike the experience that the US dairy industry has faced in the in the last two years of highly pathogenic avian fluenza H5N1, highly transmissible from cow to cow, the New World Screwworm is not directly transmissible from animal to animal. Obviously, the more flies you have, and if they continue to reproduce, it means higher risk for more animals on that farm. But typically what happens is only a single animal or a few animals are found at the beginning of the process. And so what happens is those individual animals are treated, and essentially you remove the larvae, and there's a number of uh topical products that can be utilized to disrupt their life cycle. And then you work to make that animal healthy based upon whatever damage the larvae have done. In some cases, like particularly in the case of newborn animals, calves and and and lambs and and goats, if it's left untreated, it does have a high mortality, 50% or more. And in some cases, the right thing to do with with with animals if they are if it's not detected very early, is to euthanize them, can be the right decision. The biggest impact probably on the farm will be that they will be placed under quarantine. They will be allowed to move animals under permit, and there may be there's visual inspection requirements for being able to move animals. There might be requirements for use of prevention treatments, and this is not only for the farm that has an infestation on it. There's actually zones that are set up when an infested animal is found. So you have the the farmer ranch where the animal is found, then you have a 20-kilometer zone around that, and then an additional 20-kilometer uh surveillance zone around that, and particularly those in the infestation zone may also have additional, will have additional requirements on them for their ability to be able to move animals out of that zone. So that's really, I think, the major impact. If you are at a lactating facility and there is a requirement to utilize uh, say, a prevention treatment for the whole herd, maybe the infestation is such that it's deemed that that is the best way to help uh contain the issue on that farm and in the best interest of the animals. Right now, there's only one product approved for prevention purposes in lactating dairy cattle. It does have a 19 and a half day milk fordrawal period from its last use. We're very happy that FDA and the pharmaceutical companies have been working diligently to get conditionally approved and emergency authorization use of uh drugs for dairy animals and all livestock and domestic animals in general. But we don't have a lot of things right now in our toolbox for lactating dairy cows.
SPEAKER_06Okay. What about calves? Can that same drug be used for calves?
SPEAKER_02Yes. And there are also a number of other drugs that are approved for use in calves for prevention purposes. There are also additional drugs and insecticides that are also approved for an animal that has an infestation. There's a couple of topical products, a spray product and a gel that can be used. Those also come with milk withdrawal times, but they can't be used for prevention purposes. There is also slaughter withdrawal times as well, which are in all cases longer than any milk withdrawal time. They're typically 30 days or a little bit longer.
SPEAKER_06Now you mentioned when you were talking about that, lambs and goats. What other animals? I'm assuming sheep and goats are vulnerable to this too. Any other farm animals? Dogs, cats?
SPEAKER_02Yeah, basically any any mammal has the potential to be a host for the New World's screwworm larvae. To date, there have been cattle, sheep, goats, uh, and two dogs in the U.S. In Mexico. It's been found in horses, pigs, even can infest humans. There was a uh case in the US uh earlier this year from a person who actually became infested during a trip to Central America. And so, you know, certainly not does not occur as often as you would see in livestock or in wildlife, but can also occur in people. And so when we think about people that are also in these places, they also need to be cognizant of any any wounds that they might have and make sure that they are also checking themselves.
SPEAKER_06So you mentioned wildlife. Are there any programs to monitor wildlife in these areas that they've seen this already?
SPEAKER_02Yes, there is wildlife monitoring being conducted in Texas today, and that's being overseen by the federal government and the state of Texas. So far, they have not found any uh wildlife with infestations. Obviously, people are seeing domestic livestock more often than they are seeing the wildlife. I don't find it unusual that they haven't found anything in wildlife yet. I imagine, based upon the the geography of where domesticated animals have been found, that there probably have been some wildlife that uh have been infested, just not found yet.
SPEAKER_06What information or direction does uh National Milk Producers Federation give and with this outbreak?
SPEAKER_02So, what we've been doing is we're working to make sure that dairy farmers have practical science-based information and timely updates about what's happening. Uh, so we have a resource page uh on our nmpf.org website specifically for New World's Foodworm. We have fact sheets that we've developed specifically for dairy farmers on there, also information from USDA, FDA, and individual states. Many states now have put in place requirements for uh movement of animals into their states when they come from the counties or the zones uh within Texas where they have found newer screwworm infestations so far. We are working with USDA, FDA, state animal health officials, private practicing veterinarians, making sure that we get the resources on identification, prevention, understanding the movement requirements that may be in place, knowledge on treatment considerations, and again, helping to bridge that process between the dairy farmer and the state and federal animal health officials. In particular, if they believe that they have something they that they think might be New World screwworm.
SPEAKER_06Sure. And I would imagine these fact sheets have photographs and that kind of thing to help that you can train employees to be on the lookout for. Yes.
SPEAKER_02In fact, one fact sheet that will be finalized uh and on our website this week has a few photos of a couple of the beef calves that have had naval uh infestations because that visual to see what it looks like I think is very impactful. Sure. And so we're doing our best to provide those visualizations. They're not always easy to look at, but we think they are important for people to understand what it looks like when it happens.
SPEAKER_06Any other advice or information that you wanted to share?
SPEAKER_02Yeah, maybe a couple of final closing thoughts here. Sure. The first is the uh the uh area where in Texas where they have found uh infested animals, while about half of them have been cattle, they've all been beef cattle at this point in time. And those are not commercial dairy production areas. So it's not in areas yet where there are commercial dairy farms. That being said, the uh closest dairy area in Texas to an infested animal is about 100 miles away, and that's in the Stevensville dairy shed. So 100 miles is is a long distance, but sometimes it's not. So want to make sure that people understand that there is a, you know, the closer you are to where it has been found, your risk is elevated. Sure. I think the other thing that I want to remind folks is don't panic, but pay attention. Unlike H5N1, if it gets into your herd, it's probably only going to be a single or a few animals rather than having a large clinical outbreak on your farm. But it is a serious animal health threat. The US has successfully eradicated it before and it's bringing into place the ability to do so again. Luckily, because the New World Schoolworm fly is sensitive to temperature, we get a chance to knock it down during winter. Might not necessarily be gone, but that is uh one helpful step in uh breaking the life cycle. But when we look at where how we move our animals today, we want to make sure that we're very careful not to move it to other geographies uh due to our own movement of animals. And that's, you know, our livestock, but also even for the general public with the movement of their of their pets. Over the July 4th holiday, there were lots of places in the US that were, you know, 100 degrees or more. And so this fly can live anywhere in the continental US for many months of the year. And we want to make sure that we do our best not to move it to those places. It may be a low risk the further away from Texas that you are, but it's not a zero risk. And so we want to make sure that everybody uh has an understanding about it. But very particular, the closer you are to where infested animals have been found. I do think that you have an more elevated risk than people that are farther away. A couple of places for information. I mentioned the national milk website nmpf.org, and we have a big banner right on our homepage with our New World Screwworm resources for the uh federal government. Uh, screw warm.gov uh is the great place to go. It's got consolidated information from USDA, FDA, and EPA all in one site. And they update that information on a daily basis in terms of where new infested animals may be found. And they link directly to the Texas Animal Health Commission and its map of the infested and surveillance zones for places where it has been found in Texas so far.
SPEAKER_06Well, thank you very much, Dr. Junker. I really appreciate all the information you've given us a lot to think about. And I appreciate your uh advice to not panic, but just to be aware and actively watching for this. So I appreciate that.
SPEAKER_02I appreciate the opportunity, Connie. And through that diligence of being prepared and not panicking if it happens on your facility, we will get through this.
SPEAKER_06Right. Just contact and work with your veterinarian. All right. Well, thank you. I'm Connie Cooper with Seal Pro Silage Barrier Film by Connor AgriScience. And now it's time to put your harvest plans into action by making sure you have all the supplies you need, which includes oxygen barrier film like SEALPRO. If you need anything, give us a call. You've been listening to the Dairy Voice by Dairy Business News. Please subscribe, like, and share this podcast with everyone that you know. It's lots of great information from Dr. Jonker today. So as we enjoy summer and head into fall, I'll remind you to stay safe out there. And thank you for listening, everyone. We'll talk again very soon.