Science: Parasitic Bugs Are Making Combacks Across The Country

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0:31In 1966, the United States declared victory over a destructive, flesh-eating parasite that devastated livestock. The New World screwworm is a fly whose larvae burrow into the living flesh of mammals. It was eradicated after a long campaign that involved releasing millions of sterile flies over infested areas. Last week, the new world screw worm came back. The U.S. Department of Agriculture confirmed five cases in Texas and New Mexico, three calves, a goat, and a dog. These are the first cases in the food supply in decades. Federal officials say the meat supply is safe, but the cattle industry is on high alert.

1:09The U.S. cattle herd is already at a 75-year low, beef prices are high, and a screw worm outbreak could make it worse. Later in the show, will turn to another critter wreaking havoc, ticks. The population is growing and spreading across the U.S., including in areas that haven't had to deal with ticks before. Emergency room visits for tick bites hit a 10-year high in April for that time of the year. And a growing number of Americans are discovering they've developed an allergy to red meat triggered by a tick bite. I'm Jen White. You're listening to the 1A Podcast. We'll get to that and more right after this short break.

1:44Stay with us.

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3:18Welcome back to the 1A podcast. We're talking screwworms and ticks today. And let's start with the screwworm outbreak. Here to talk about the risks and what the government is doing about it is reporter Leah Douglas. She covers agriculture and energy for Reuters and has been following the outbreak. Leah, welcome back to the show. So much for having me. And Caitlin Jettelina is an epidemiologist, scientific communicator, and author of the Your Local Epidemiologist Substack. Caitlin, great to have you with us. Thank you for having me. So Leah, first, tell us more about the New World Screwworm. What is it?

3:53New World Screwworm is a bit of a misnomer. It's actually a fly, not a worm. It's a parasitic fly, and the screwworm can infest any warm-blooded animal. So you said mammals, that includes livestock, but also pets, wildlife, and in some rare cases, people. Now, five cases were recently detected in the U.S. This hasn't been seen in decades. What's the risk of further spread? The experts that I've spoken to have said that they do expect the screwworm fly to continue to spread. As you said, this was a pest that was eradicated from the U.S. in the 60s and really pushed really far south through Central America all the way to the Darien Gap through a collaborative effort between the U.S.

4:39and Mexico and Central American countries. And it's been encroaching further northward for the last several years. And now that it's crossed into Texas, there is an expectation that it will continue to spread. However, there are treatments and the federal government is pouring resources into this, which I'm sure we'll discuss too. Caitlin, what do symptoms look like for animals and for people? Yeah, this is an incredibly painful experience. Like the previous speaker said, this is where eggs hatch into tissue and further burrow into. And it's exactly as bad as it sounds. and the living flesh really hurts and it smells a lot and it is fatal if it's untreated.

5:26What's the treatment for the parasite? It really is a combination of things there. This is one of those moments where ivermectin, I don't know if you guys remember that from COVID, can be used for animals. the effectiveness among humans is unclear, but it does remain on off-label use, and there is positive anecdotal evidence for human use as well. Now, the reappearance of screwworm in the U.S. wasn't a surprise to the Department of Agriculture and people in the cattle industry. We got this message from Tom Patterson. He's president of the New Mexico Cattle Growers Association. This is something we've known was coming for the past 12 to 18 months.

6:12The only question was when it would happen, and now we have that answer. Aaliyah, what is the government doing to try to contain the outbreak? Well, I've heard exactly that sentiment from so many people I've spoken to, whether they're along the Texas-New Mexico border or working in the federal agencies. The administration has been working for at least a year to try to stand up preparation for what was really seen as an inevitability that the screwworm would cross into the U.S. They've surged personnel from the USDA to southern Texas. There's been efforts between animal health drug makers and the federal government to build a stockpile of treatments.

6:52The Food and Drug Administration has issued about a dozen emergency use authorizations to enable fast tracking of treatments that can be used in pets and livestock. So it has been a multi-agency public-private effort over the last year that now is being put to the test by this growing number of cases. There's been a lot of finger pointing about who exactly is to blame for the parasites reintroduction into the U.S. Here's Secretary of Agriculture Brooke Rollins at a press conference in Texas on Monday. We have been prepared and preparing since early last year for the reemergence in America. Now, this does trace back to the last administration and the open border policy and the movement of millions of people and their animals up through from South America through Central America.

7:44Now, Leah, we hear there Rollins putting responsibility on the Biden administration, but what do we know about how the fly came back to the U.S.? Certainly, livestock movement is a significant factor there. There's been some reporting and some discussion that perhaps illegal movement of livestock across, you know, sort of circumventing the procedures that were trying to keep pests like this suppressed in Central America and in Mexico perhaps contributed to the spread. The Biden administration was working on screw worm in the sort of months before the administration ended. The pest started moving north about 2022, 2023.

8:28And so there were efforts under the last administration to start preparing. At the time, it was still in far southern Mexico, so it wasn't nearly at the urgency level that it's become under this administration. So there has been finger pointing, and the government of Mexico has rebuffed some of the Department of Agriculture's blame southward for the spread. Well, it's also important to note that under DOGE, the Animal and Plant Health Inspection Service in the USDA lost employees as part of the cuts to the federal workforce. But the Trump administration also made cuts at the USDA, and some of the programs targeted were monitoring and responding to the New World screwworms.

9:14So has that played a role in this resurgence? So the Animal and Plant Health Inspection Service, which is the arm of the USDA that manages animal disease outbreaks, saw about a 25 percent attrition of staff last year between normal attrition, but primarily people who are taking some of the buyouts that were led by DOGE. And the administration has said that, or Brooke Rollins has said, that there's been no impact. She said zero impact on the screwworm response from those cuts. However, Democratic senators and some veterinarians, some ranchers in Texas are concerned about the quality of the USDA response and have raised the specter of these staff departures as a potential risk as the outbreak continues.

10:03We got this question from Will who asks, what is the difference between screwworms and blowflies? Does North America also need to worry about blowflies? Caitlin, what can you tell us? Screwworms are a type of blowflies. They are part of the same family and not as fatal or impactful as the cousins, but they are related. and something for us epidemiologists continue to keep an eye on. Well, let's turn back to Tom Patterson of the New Mexico Cattle Growers Association. This is what he says he's doing on his ranch to monitor livestock. We pay attention to wounds, irritated behavior, animals that are separating themselves from the herd, loss of appetite, head shaking, unusual odors, or the presence of maggots in a wound.

10:56If possible, and sometimes it's not possible, We're going to be postponing elective procedures to create open wounds until we know more about the extent of the situation. Leah, you've been talking to ranchers. What are they telling you about the potential impact on the cattle industry and the meat supply? Well, the USDA has estimated that a widespread outbreak of screwworm in Texas could cost the industry there about$1.8 billion. in terms of some factors that could contribute to that are the costs associated with that heightened monitoring that was just described, the administering of treatments, the veterinary care, and so on.

11:35So there is a potential economic impact to the livestock industry. And we also know if you're shopping for beef in the grocery store, prices of beef have been very high. That's been contributed to in part by the border closure between the U.S. and Mexico. The U.S. has not been importing cattle from Mexico as one of the measures to keep screwworm at bay. So there also could be a consumer impact down the line of potentially even higher beef prices. Well, Caitlin, just to be clear, because I'm sure people who eat beef right now are wondering, is it safe to eat beef? It is. Beef is safe to eat. This is one of the main reasons.

12:14I mean, there's two main reasons. One, if the animal dies, the larvae basically abandon ship. And so So there's that. If the cows are infected, the meat is no good, and so they aren't slaughtered. And this is why this parasite is just so problematic, right? When cattle are infected, both the meat and the hide are damaged and considered a loss to the rancher. Well, that's Caitlin Jettelina. She's an epidemiologist and scientific communicator. She found at the Substack, your local epidemiologist. She's staying with us to talk about another parasite, ticks. Also with us today, reporter Leah Douglas.

12:51She covers agriculture and energy for Reuters. Leah, thanks for joining us. So much for having me. And just a quick clarification. We got an earlier question about blowflies. The common blowfly feeds exclusively on decaying flesh, while screwworms eat living flesh and healthy tissue. Just an important note there. We'll be right back.

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15:05Experience is getting more common as the U.S. tick population grows and spreads. Ticks are responsible for spreading roughly 90 % of all vector-borne diseases in the U.S. Lyme disease is the most common, but other infections are on the rise too, like the tick bite-induced meat allergy called alpha-gal syndrome. And just to add insult to injury, a tiny tick bite can even attract a screw worm looking for a spot to lay its destructive eggs. So how can you protect yourself, and what should you do if you are bitten by a tick? Caitlin Jettelina is still with us. She's an epidemiologist and scientific communicator.

15:41She writes the Substack, your local epidemiologist. And joining us now is pathologist Dr. Bobbi Pritt. She chairs the Mayo Clinic's Division of Clinical Microbiology, where she specializes in parasitic and vector-borne infections. She's also helped discover two new tick-borne pathogens, including one that causes Lyme disease. Dr. Print, welcome to 1A. Thank you for having me. So April is the start of tick season, and this year emergency room visits for tick bites were higher than in the 10 previous Aprils. Why are we seeing this increase? Well, I think that the ticks are out and biting, and with the earlier start to our spring, the ticks started coming out as soon as the ground thaws and the snow melts.

16:24And now we're having people with the increased awareness of tick bites getting exposed to ticks and realizing that they could pose a significant health threat to them. So they're going to their health care providers. So you said these ticks could pose a threat to their health. Are we seeing a corresponding increase in tick-borne disease? Well, we are, yes. And actually, if you look at cases of tick-borne diseases in the United States, they've more than doubled since 2004. Every year, they continue to go up. Caitlin, what are the most common diseases ticks carry? The most common, I mean, so there's over 900 species of ticks, but only about 20 tick-borne diseases.

17:06So not every tick you encounter will give you a disease. I think that's important to know. But the most common tick-borne disease is Lyme disease. It's this bacterial infection transmitted by two species of ticks in the United States. And it's most common because this black legged tick has a relatively broad distribution. And this bacteria that it can carry has well - established populations, mainly in white-footed mice, as well as white-tailed deer reservoirs. So you said two species of ticks carry Lyme disease and the long-footed tick was one of them? One of them is the black legged tick. Black legged tick.

17:50And what's the other? Sure. It is, I'm actually not entirely sure. Dr. Pritt, any insight there? Yeah, I can jump in. It's the western black-legged tick Ixodes pacificus, which is found on the west coast versus the one that we know in the northeast and the upper midwest, which is Ixodes scapularis. They're cousins. Is there anything distinctive about these ticks that might help someone identify them, Dr. Parade, if they find one? Yeah, well, they're pretty small. But one thing to keep in mind is that as they start feeding on you, as disgusting as that sounds, they're drinking your blood and they get larger and they can be quite large.

18:30But the tiny size when they first bite you can be very challenging. In fact, the nymphal tick is the size of a poppy seed. and then even the adult ticks are only about the size of a sesame seed. So I think that's significant to know when people are checking themselves for ticks. They might think of what we call the dog tick dermis center, which is a little larger, but you really have to look for those tiny little specks like you said in your opening. Well, ticks and the diseases they carry are showing up in parts of the country where people didn't previously really worry about them. For example, the lone star tick, which was primarily found in the South, In recent years, it's shown up in the Northeast and in the Great Lakes.

19:12Why are we seeing ticks in new places, Dr. Pritt? Well, part of it is just their natural expansion, and they can be carried by migratory birds. They can be carried on deer. But then also the weather is supportive of their continued expansion. Ticks do well when it's warm and humid. They don't do so well in the dry areas, so there may be some parts down south where we'll see less ticks in the future. But in the north, we know that our winters have been milder. And with that climate change, those aggressive Lone Star ticks are more able to survive our winters. In fact, we now know the Lone Star ticks are established in Wisconsin.

19:50They're coming up into Minnesota, where I live, and we have very harsh winters. And they're all up the northern seed board right up into New England. Now, Caitlin, you mentioned Lyme being the most common and probably familiar tick-borne illness, but what are some of the others? Yeah, I mean, I think one of the most fatal tick-borne diseases is the U.S. Rocky Mountain spotted fever, but it is rare, so that's good news. Between 250 and 6 ,000 cases occur in the United States every year, but the mortality rate is high, up to 30 % without prompt treatment. This one usually occurs in five states, North Carolina, Tennessee, Oklahoma, Arkansas, and Missouri.

20:38But again, I think you said it earlier, one of the most talked about tick-borne diseases beyond Lyme disease is the alpha-gal syndrome. And we'll talk more about that in a moment. Dr. Britt, Health and Human Services Secretary Robert F. Kennedy Jr. announced a multi-million dollar plan to tackle Lyme and tick-borne illnesses. Tell us about those initiatives. Sure, I'd be happy to. I was involved in some of the earlier initiatives back in 2020 to 2022. This is a new initiative now, though, where there is a national goal of reducing Lyme disease by 25 % by 2023. So less than 10 years to go now. And there have been some important new investments in tick control research, next generation diagnostics, which is what I do, is the diagnosis of Lyme disease, additional findings for research on alpha-gal syndrome.

21:28And I think what's nice to know is there's a real focus on patient care, public awareness, and also some of the ongoing symptoms that people experience with Lyme disease after they've been treated, but continue to have ongoing health symptoms. Well, Caitlin, it is summer. We're in peak season. Many of us plan to spend a lot of time outside. What's the best way to protect ourselves? Yes, and we should be spending time outside. It brings so much joy. And the great thing is that we can implement multiple layers to prevent tick bites. And if we prevent tick bites, we prevent the risk of illness. And set aside on clothing really helps.

22:09Put it on shoes and pants. Effective repellents like DEET protect for about six to eight hours. Other things like light colored clothing and pants tucked into socks improve the visibility of crawling ticks on clothing. And once you're done going outside, check for ticks, right? Ticks climb up your body seeking really a suitable feeding site, right? Warm, moist, protective spots. It can take 15 minutes to hours for them to really select a location like your groin or armpits or behind the ear. So be sure to check all crevices before spending time outdoors. Also other tips, shower. After being in these tick habitats within two hours, it helps wash off these crawling things.

22:59And then remove ticks promptly if you see one. I think that most pathogens can be transmitted if a tick feeds for a certain duration. So like mechanical remover, like literally using tweezers is really the only recommended method. And you talked about areas where ticks may be more present. Are there places we should maybe avoid or be particularly cautious if we visit them? I mean, across the United States, the most Lyme disease is up in the Northeast, although we are starting to see it spread more and more. And in the environment, it's tall grass. These boogers step on tall grass, and they can easily jump to us while we're hiking or while we're out in the outside.

23:50And just a quick clarification. Ticks don't literally jump. They also don't fly. They climb onto grass or bushes or leaves, and then they latch on when an animal or a person brushes by. They then crawl around and find a suitable feeding spot. Now, there are a lot of products out on the market. There are also natural and homemade insect repellents. Caitlin, what's a baseline that we should look for if we're searching for a repellent that will work against a tick? I mean, really look for DEET, right? There's a lot of natural, or like you said, homemade tick repellents, and they're not necessarily safer or more effective.

24:25DEET has over 70 years of data demonstrating safety and effectiveness. These essential oil-based repellents are ineffective and also can be dangerous, especially for young children and pets. Well, it's not just humans who are susceptible to tick-borne disease. We've heard from several of you about your pets. Barbie in Indiana left us this voicemail. When we were kids back in the 70s, we had a bunch of dogs and cats outside because we had a farm. We hardly ever had ticks on them. And if we did, we just picked them off. We didn't have flea collars and tick collars and none of that stuff. Now it's unheard of.

25:07You cannot leave your dog without protection because they'd be loaded with ticks. And Wendy lives in the Catskill Mountains of New York. I have had many ticks on me, and I have had Lyme previously. But what I'm really concerned about are my dogs because they are always picking up ticks. My worry is that the flea and tick medication that's available is just not working because my animals get that every month, yet they continually contract Lyme disease from tick bites. Barbie, Wendy, thanks for those messages. Dr. Pritt, what do we know about the protections available for animals? Do they work? Well, they do when they're used properly.

25:52And thankfully, there are a number of different things we can do for our pets. As we were just talking about, prevention is still the best defense, preventing those tick bites to begin with. But, well, let's just talk about dogs. They probably have the best established protections. They have the oral medications, the topical products, the tick colors. They also have a Lyme disease vaccine for dogs, which is highly effective. So all of those things are important in protecting your pets. I'll also add, though, that pets are also an important method of bringing ticks into the household. And so as we were discussing, checking yourself for ticks when you come inside after being outdoors, don't forget to check your pets too because they could bring ticks into the house.

26:36Even if the ticks aren't biting them, they could then bite you. We're speaking to Mayo Clinic pathologist, Dr. Bobbi Pritt, also with us epidemiologist, Caitlin Jettelina. I'm Jen White. You're listening to 1A. Dr. Pritt, you mentioned a Lyme vaccine for dogs. Why isn't there one for humans too? Well, it's interesting you say that. There used to be a Lyme disease vaccine, but at the time it wasn't the risk. Lyme disease was not the risk it is today. And there just wasn't a large demand for it. So it was pulled from the market, not because it wasn't efficacious, but just because it was low sales and poor public acceptance.

27:16And so do you see now with this higher presence of ticks that that might come back on the market, that there may be increased demand for it? Yes, so there actually are a number of organizations working on Lyme vaccine. The Pfizer-Valneva vaccine is probably the furthest along. They recently reported their phase three trial results, which showed about a 75 % efficacy against Lyme disease. And they are planning to submit the vaccine to the regulatory authorities soon. So I think we should keep our eye out on what's going on with Lyme disease vaccines. there hopefully will be something available in the coming years.