What's the deal with ticks?

22:09And the Powassan virus is very scary.

22:11Emily Oster:It's very scary. So, all right, if you look this up, what you'll find is that Powassan virus is a virus with no treatment and a 10 % case fatality rate, which is like, oh, so I can walk through the woods of Connecticut where deer tick abound and I can have a tick on me for 15 minutes and then I have a 10 % death rate. This is not entirely true, but the broad strokes and the data we have will lead to some people saying these things. So what the virus does in most people is nothing. Now, that's not what you'll see when you Google. What you'll see when you Google is that Powassan virus causes meningitis.

22:48Emily Oster:So it's a brain inflammatory virus. And indeed, if you develop meningitis from Powassan virus, you're going to go to the hospital. You're going to be very sick. It's a virus. So antibiotics don't work. You're going to get supportive care, IV fluids and pain control and fingers crossed. and the case fatality rate is about 10%. So that's super scary. But most people don't ever get symptoms from it. Yeah. And I think we sort of have to know that that has to be true just based on the base rate. There are many, many, many cases of Lyme every year spread by the same tick. There are a very small number of cases of this.

23:33So far in 2026, There have been 30. Last year, there were 76. That's a very small number. The US is 330 million people. The Northeast has many, many, many tens of millions of people. This is a very small number. And there is some seroprevalence work, which means like testing people to see if there's evidence that they've been exposed to this would suggest much higher rates of exposure.

23:55Emily Oster:So you have an antibody to the virus, but you never were sick. Yeah. So one way to think about this is conditional on arriving at the hospital, very sick with this. The fatality rate is quite high. The vast majority of people who get this do not actually develop this virus. So it's not that it's not scary. Like it is. This is very scary. Yeah, it's scary. But there are many other things that are scarier in the world. Yeah. Yeah. If insofar as this motivates you to like do the anti-tick measures, we'll talk about some of the things you can do to prevent getting tick bites. then great. But yeah, don't let it keep you up at night.

24:31I mean, I do think things like this are very salient to people. When you say there's a thing that could happen, you get bitten by a tick and you could have a 10 % case fatality, that is really scary. And then that lives in your head. Because people are very poor at understanding small probabilities, the fact that it's 76 out of 75 million people, it just feels like, well, it could be a chance. It could happen. It's like the lottery. It's worth putting it in the space of, you know, you are an awful lot more likely to die in a car, in your car on the way to the woods than you are to die of a tick that you get in the woods.

25:08I'm not saying you should be afraid of going hiking, but like in the space of risks you're taking, this is very small.

25:16Emily Oster:The health benefits of going on that hike probably outweigh any risk from the policy. Yes, if you did the sort of minute calculation, you're on a good path. Um, absolutely. Absolutely. Okay. Yeah. So the second way, so that's tick infections and there are other diseases that, that can be spread by ticks in this same way. Yeah. What's your favorite other tick infection? I know so many. No. Um, I mean, I think for me, I guess, I guess ehrlichiosis. Um, I, yeah. Um. What's my favorite tick-borne disease? I didn't think this was such a hard question. Hold on. We have to edit this a second. Okay. Well, let me go back.

26:03Emily Oster:I had to think about it. Okay. Yeah. There's so many interesting tick-borne diseases. And I feel like people have their favorites and someone's going to be like, you didn't mention Rocky Mountain spotted fever. You didn't mention anoplasmosis. I think babesiosis, to me, because we see this in the hospital, not infrequently, and it is the closest thing to malaria that we have in the United States. So babesiosis is a bacterial infection that gets a parasite that gets inside red blood cells. So just like the malaria parasite. I mean, it's not the same. It's a different parasite, but that's its mechanism.

26:43Emily Oster:It gets in these red blood cells and people come in with severe anemia. and actually like very similar symptoms that malaria presents with. So you sort of learn about malaria in medical school because malaria is the biggest killer of humans, infectious disease killer of humans in the world. And then, you know, you come here to Connecticut and you see people coming in with the same symptoms and it'll be babesiosis. There are about 100 to 500 cases of this, your favorite disease every year. Okay, great. All right. Great for you. But I'm just telling people that's not very common. Yeah, there is selection bias here, too, because a lot of people with babesiosis will have some kidney dysfunction.

27:20Emily Oster:So they call people like me. OK, so the second thing that ticks can do is they can poison you. And the best poison tick disease is tick paralysis. It's the best one because it's super interesting. It's a neurotoxin in the saliva of some kinds of ticks and it causes paralysis. Mm-hmm. And it causes a very particular type of paralysis. So what it is, is it's a flaccid paralysis, so a weakness as opposed to a spasticity. So there's kind of two types of paralysis, a weak paralysis that goes from your legs and goes up your body. And if you're a doctor listening to this and you saw a patient that had that pattern of paralysis, you'd be like, that's Guillain-Barre syndrome because it looks exactly the same.

28:09But actually, it's ticks. But actually, it's ticks. If you remove the tick, the paralysis goes away. Which is awesome. Which is awesome. And there is an episode of House in which this happens. Yes, there's an episode of House in which there is a person, a teenage girl, and this is what House thinks is happening. And everyone says that he's an idiot because they can't find a tick and they look for a tick and blah, blah, blah. But then it turns out that her boyfriend had snuck in and he had picked up a tick and they had had sex. And actually the tick was in her vagina. And that was what House identified.

28:47So for me, this is like stuck in my – I don't know why. I really like that show.

28:52Emily Oster:Oh, no. I like the show too. And so then the things – and that was an episode that stuck with me and also the fact that they always thought it was Wilson's disease. Like every single time it was Wilson's disease. Oh, that's funny. It's like not a lot of people get Wilson's. Anyway, that's a different topic. Yeah. Wilson's is a disease of no relation, disease of copper metabolism that causes liver failure. So it is worth it to know for clinicians that if someone presents with Guillain-Barre syndrome, that you should do a tick check. Generally, we advise looking at the scalp. But I suppose you should do a - That's why House is a genius.

29:25You should do a thorough - He doesn't just do the first thing.

29:27Emily Oster:You should do a thorough tick check if you have a patient with Guillain-Barre syndrome. But it is cool. The paralysis goes away within hours of removing the tick. So miracle stuff. All right. Third thing is that the tick can rewire your immune system in this crazy way. And this is the one actually everyone has been talking about. Or at least one of the diseases that's caused by this mechanism, which is alpha-gal. Alpha-gal has been the talk of Nantucket this summer because one of the things that happens, the thing that happens with this is that you cannot tolerate meat. Yeah. And there's been some discussion, which I think is totally overblown, that like the stores on Nantucket have stopped stocking hamburgers because too many people have alpha gas, which I don't think is true.

30:22But this is like –

30:24Emily Oster:It's probably the Ozempic. I would guess it's the Ozempic. But let's, you know, move on. But it's totally weird. Oh, it's super fascinating. And I alluded to this earlier that allergies tend to develop when you get exposed to a potential allergen, not through your GI tract, like through some other way. So what alpha-gal is, is I guess we need to know is that every species, every mammalian species on the surface of their cells has a sugar called galactose alpha-1 ,3 galactose. except the old world apes, the old world primates like us and chimpanzees and gorillas. So we lost that in our evolutionary history.

31:09Emily Oster:We'd like the gene to make that sugar just went away. We do not make it anymore. I don't think it causes us a particular problem. I don't know. That's evolution for you. All other mammals except us and the chimpanzees and the gorillas. Okay. So we don't see that protein, that sugar in our body, but we eat meat. And as long as it goes through our GI tract, that's fine. This tick, and in this case, it's the lone star tick primarily, in its saliva has galactose alpha-1 ,3 galactose for other reasons, presumably. Obviously, it's not mammalian, but it injects that into you. And in theory, because it's going in through your skin and not through your GI tract, you can develop an allergy to it.

31:46Emily Oster:What is a little unusual about this allergy is it's not usually full-blown anaphylaxis where like you, I don't know, you have a bite of hamburger and two minutes later you're on the floor, it's usually hours after. So you probably have to digest some stuff and it's got to get into your system for things to happen. And usually the presenting symptoms are GI in nature, like pain, bloating, diarrhea, sometimes vomiting. And because of that time between when you ate and when you got sick is so long, it's not immediately obvious to people that it is an allergy. There can be allergic symptoms as well.

32:24Emily Oster:So it's a really interesting bit of physiology that like we're really only just starting to understand. It is also a place where testing has revealed that a lot of people seem to have been exposed in this way. So they're like, there's a test for this. You can test for the serum alpha-gal antibody. And when you do that in some sort of places with a lot of chicks, you get actually quite high rates. So somebody did a residual blood donor sample and the seroprevalence was like 24 percent. Wow. And of course, 24 percent of people in, you know, Arkansas, Kentucky, Missouri and Tennessee are not allergic to meat.

33:03Emily Oster:It would be devastating to the local economy. And so, you know, and we're seeing like 500 cases a year diagnosed of this. So I think it's one of these places where obviously people have this without actually having symptoms. And it does go away for most people over time. That's right. That's right. If you avoid further tick bites, the symptoms get better. But for some people, they can really never eat meat again. And the immune system is an incredibly complex thing. And an antibody titer is not the same as a full-blown immune reaction. So it can be hard to tease out. But stay away from those alone to start ticks.

33:41It's so interesting. It is. It is. I don't know. Absolutely. The body is very cool. Absolutely. All right. So those are your three big tick approaches. And we're very sorry to the entomologist listeners that we have not covered Perry's spreadsheet of ticks, tick-borne diseases. But we're going to take a break. And when we come back, we're going to talk about Lyme disease.

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35:53Emily Oster:This is according to Ooglu Speed Test Intelligence. Date a second half of 2025. All rates reserved. Redeemed money back guarantee within 30 days of cancellation. All right, we're back and we're going to talk about Lyme, which is the most common tick-borne disease in the U.S. It's actually not clear how many cases there are in a given year, but it's in the hundreds of thousands, we think. And Lyme disease really begins with some moms in old Lyme, Connecticut, who had identified, they all had children who had been diagnosed with juvenile arthritis, rheumatoid arthritis, which is basically joint pain.

36:36And they just felt that was not, could not really. Didn't seem right. It didn't seem right. It's not very common. That isn't typically a cluster disease.

36:45Emily Oster:Why do all these kids have it? Why do all these kids have it? And they pushed and pushed and pushed. And eventually a researcher at Yale sort of took them seriously, worked this up and identified a bacteria, which is spread by ticks, that was causing this set of symptoms and conditions. And I actually think this story, and we can talk much more about the microbiology, but just from a kind of sociological standpoint, this story is the beginning of Lyme disease. And it's also like the middle and the end, because so much of what happens in the discussion of Lyme disease, particularly around chronic Lyme, feels like patients feel like they're not being listened to doctors by doctors.

37:31And this is like it sort of started. It started that way. It started that way.

37:34Emily Oster:It's DNA. And so so that's that's where that's where the start. And this all happened in like the mid mid 1970s, early 1980s. Yeah, it was Willie Bergdorfer who actually identified the bacteria. It's called a spirochete. It's kind of a spirally shaped bacteria. It's named after him, Borrelia burgdorferi. We'll hear more about Willie burgdorfer when we talk about some of the interesting Lyme disease conspiracy theories that are out there. But before we get to that, we should just talk about Lyme disease. What is it? What is Lyme disease? Tell me what it is. I think people broadly know. But OK, so we've got this bacteria that lives in a tick.

38:11Emily Oster:The vector is typically the deer tick. It can be carried by some other ticks. And as you pointed out, the nymph stage is where we see most of the transmission, not because it's uniquely infected, but because it's so tiny, poppy seed size, little black thing, super easy to miss, especially in the hair. As you said, it takes a while for it to transmit. That's actually because the tick has to start feeding and process. And it actually metabolizes some of your blood and it puts it back in you. And that takes some time. And that's, we're getting creepy again. But that's actually how the spirochete gets into you.

38:48Emily Oster:And the entomologist will go out and like take samples of deer ticks and look and just measure the ticks. And about 25 to 50 % of them are Lyme disease positive. So it's like, if you have a deer tick, the chances are it's got Lyme disease in it, or at least the chances are very good it's got Lyme disease in it. Clinically, the standard way to define Lyme disease is, we say, early or localized Lyme disease and then late or disseminated Lyme disease. And if you see me using air quotes or trying to hedge my bets with the tone of my voice, that's because various other societies have created different staging systems.

39:26Emily Oster:So this is the most common one. Early localized disease is the rash. It's known as erythema migrans, classic target-shaped rash. Looks like a bullseye. Looks like a bullseye. Correct. And it can be, you know, you'll see pictures online that's like, oh, it's clearly a bullseye. But my daughter had Lyme disease. I took a picture of like a vague ring-shaped thing on her back. I was like, I think this is erythema migrans. And I sent it to her pediatrician and they were like, nah, it doesn't really look like that. Like it's too faint or whatever. It wasn't... Yeah, she had Lyme disease. So, okay. Also in that early period, you can get those flu-like, cold-like symptoms, fatigue, headache, and stuff like that.

40:10Emily Oster:And ideally, you want to treat at that point in time. You don't want to let it get to disseminated Lyme disease. That's where you can get a lot of other symptoms. Now it's spread throughout your body. And so you can see symptoms in other organ systems. Classically, joints. My daughter, because she wasn't treated at the early stage, had a big like joint effusion in her knee. That's how she ended up getting diagnosed. But you can have cardiac abnormalities. Facial palsy is actually fairly common. You know, it can look almost like you had a stroke or something like that with, because there's some, some nerve stuff there.

40:42Emily Oster:This all gets better with treatment. And I will say explicitly, you can have Lyme disease without the rash. So 70 to 80 % of Lyme disease cases will have erythema migrans, but not every single one. So you do have to be suspicious. So part of what is complicated here is, of course, for some set of people, like, I'm going to divide a little bit into kind of like the best, almost like the best case scenario here, which is you have an identified tick bite. There is a bullseye shaped rash that you notice immediately. And then there is a very clear treatment. There's no testing. We assume that you have Lyme disease, that you take a dose of doxycycline and that fixes the problem.

41:26doxycycline is an antibiotic. It deals with the bacteria and we're good.

41:32Emily Oster:Yeah. Several doses of doxycycline. Several doses. It's not yet. Don't just take one. I mentioned that because there are pediatricians who will recommend a prophylactic doxycycline dose with any tick bite. No rash. You got a tick bite, just take a doxycycline. There's not good randomized trial evidence to support that. You might hear it, but that's not There is a more complicated question about if your child has been exposed to a tick, should you take the full dose of doxycycline as if you have been? And there's also some debate about whether that – Obvious risks about overuse of antibiotics. Yep.

42:07So, okay. So that's like the sort of I know what's happening. I've fixed the problem in the short term. Fine. it is much more complicated if you have gotten to this later potential phase particularly if you're not sure it was a tick you know so think about the case in which someone's bitten by a tick the tick is on for a long time the tick falls off they don't notice they never get a rash and then all of a sudden they have a series of complicated symptoms palsy nerve pain disseminated rashes There's a lot of difference. That's a hard diagnostic problem. And the testing here is actually not, it's not a single test that for sure tells you what is going on.

42:51Emily Oster:Yeah. So testing for Lyme disease, and we're going to get to this a little bit when we talk about chronic Lyme disease. So let's carve that out for a minute. Testing relies typically on looking for antibodies against the Lyme spirochete, against the bacteria. Yeah. The FDA and the CDC recommend a two-tiered testing system. So they have, you do an initial test that is fairly sensitive. So it's going to look like really, it'll pick up kind of anything. So a high false positive rate, but also a high true positive rate. An initial test, if that's positive, then you move on to a secondary test that's more specific.

43:29Emily Oster:And there's a couple of different approved tests for that. And putting those two things together in an approved laboratory gets you a pretty high ability to detect, but not perfect, to detect the disease. I think it's something like, you know, you would detect 80 % of them, 80 % of positive infections, and you'd have a false positive rate of like 10 % or so. So it's not terrible, not perfect. The problem is that there is an entire ecosystem of unlicensed testing for Lyme disease and labs that use different thresholds for these antibody levels, which can give rise to false positive rates north of 50%.

44:10Emily Oster:We'll talk about why this ecosystem exists. You mentioned at the beginning that the story of Lyme is really a story about doctors and patients not seeing eye to eye and a lot of doctors not listening to their patients. And whenever that happens, people come in to fill that void. And some are very well-intentioned and some are not so well intentioned. So we'll get there. Testing's not perfect, but not bad. It can miss early on. I mean, antibody tests can miss early on. They can also pick up past infection because antibodies maintain for a long time. So not perfect, but there is some testing you can do.

44:48This is generally not something you would do if somebody shows up with a standard rash. They're just given the diceycycline and we move on.

44:56Emily Oster:Most people would just treat. I know some docs who will treat and test too, just to like have it in the record or something. But yeah, I think if you, you know, you come up with a rash like that, you're getting. You're not waiting. You're getting treated. You're not waiting. You're not waiting. In part because the test is most likely to be a false negative early on before you've mentioned an antibody response, which is why we're giving you the daxycycline. Okay. So before we get into the chronic Lyme space, I want to ask you a question. actually i want to i'm not going to ask you i'm going to ask uh the health secretary of america a question okay about whether lyme is a bioweapon let's hear what he has to say clearly covid19 pandemic and many other global pandemics that we have have come from gain of functional research the rsv epidemic that we have that is the biggest killer of kids in this country today came from these kind of experiments.

45:51The Lyme disease almost certainly came from this kind of

45:54Emily Oster:research. Okay, so it sounds like maybe yes. Tell me where this came from. I have to admit that until I heard RFK Jr. say that Lyme disease is a result of gain-of-function research, and in other places he's described it as a literal bioweapon, And I kind of didn't know this story. And it's really fascinating. So let me walk you through why this is like remotely a thing at all and also tell you why I think it's not a bioweapon. So this all starts in 2004. There's a book by a guy named Michael Carroll. It's called Lab 257 about the Plum Island Animal Disease Center, which is on the eastern tip of Long Island.

46:39Emily Oster:And yes, there is an animal disease research center on the eastern tip of Long Island. And yes, they study animal diseases and some tick-borne diseases. And Lyme, Connecticut is just across the Sound from there. But that's sort of mostly where that story stops. Like, we don't have evidence that they were doing any particular experiments with Lyme there. However, remember Bergdorfer, the guy who discovered Borrelia bergdorferide, who discovered the spirochete. So he actually did work at a government facility that did study tick-borne diseases. Let me see if I can find the name for you. So it was a program called Rocky Mountain Labs.

47:33Emily Oster:It was indeed an entomological warfare program. So the U.S. government was interested in like, hey, can we have insects spread diseases? By the way, a thing which definitely has happened in the past. I mean, this is how we got malaria. I mean, diseases spread all the time. Insects spread diseases, but we didn't make malaria. But yes, biological warfare has happened. There are some – okay, but that's all we have. So we've got the guy who studied tick diseases was also working at the government studying tick diseases. Like, of course he was. Like, if you're going to develop this program, like maybe you have a guy who knows about tick diseases.

48:19Emily Oster:But here's the issue with all of this theory is that Lyme disease was identified in the 1970s. These programs that they're talking about were maybe open in the late in the 60s. But actually, Lyme disease has been around way longer than that. So we have direct evidence of Lyme disease infection in white-footed mice from museum specimens. So you go in back to these like little museums and you test the white-footed mice. And at least as early as 1898, we have Lyme disease in mice. So this is long before the government had any type of biological warfare weapon. The other source of evidence is that genetic sequencing can tell you how diverse Borrelia burgdorferi is.

49:03Emily Oster:If Borrelia burgdorferi were released at a discrete time, let's say in 1970 in Lyme, Connecticut, I don't know why we're doing it, but let's do it. Let's affect the people of Lyme. The genetic similarity, because it's only been, what, 50 years? It would be highly genetically similar to itself as it spread because it had a point source in time. And in fact, it's very diverse. And there are all sorts of methods to tell how long something has been around. And the thoughts are actually that Borrelia burgdorferi has a long lineage going back millions of years in mammalian species. This is also the dumbest animal, like insects to use for a bioweapon.

49:43Like mosquitoes are just a much better, much better bioweapon. Right. Ticks. And you got to leave it on for like two days?

49:52Emily Oster:Yeah. I mean, you had one job, evil scientists. Well, let me think. I've got this animal that flies around and bites you immediately. Or I have this other one that crawls around and you have to leave on. Oh, we're going to go with the crawler. What could go wrong? Yeah. Yeah, totally. I think so. So it's not a bioweapon. I guess the question I have for you is like, so why? You know, so these coincidences, it's hard not to see similar things with COVID-19. I'm not getting into lab leak versus not lab leak. But like, you know, there's a virological institute near the place where the epidemic starts.

50:29Emily Oster:I guess there's a resonance there with Lyme disease, although it's across Long Island sound. I don't know why you don't just do it on Long Island, but whatever. But like, is it because Lyme disease is scary? You know, we know it can have these long-term effects potentially. And believing that, and that quote from RFK, like he mentioned, Lyme disease mentioned RSV, he mentioned COVID, all of these things as like potential bioweapons or gain of function research, like the result of human messing with nature. And in some way, I'm getting put in my non-psychologist hat on, in some ways, it's satisfying to people to be like, well, if all these bad things out there that could happen at any time, like my kid could get RSV and could be terrible.

51:14Emily Oster:If they're the result of human malfeasance, then there is a future where we can stop that malfeasance, right? Like the good guys can win. Whereas if not, if this stuff just happens randomly and like stuff evolves and all of a sudden we have a pandemic, like we have no control over that. Is that what's attractive about these? I think it's simpler than that. I think it's that people like explanations. And so people want to understand why things are happening and they want to understand why bad things happen. And the explanation of just like animals have diseases and sometimes you get them is not actually a super satisfying explanation.

51:49It's much better to have an explanation like it is because, I mean, I think it's the same reason why people like this idea that there's a conspiracy between, you know, big pharma and big food to give your kids diabetes as opposed to just saying like food companies are trying to sell stuff and people like to buy delicious food. Like, you know, there's a lot in here where it would be nice to have someone to blame because it would help you organize and understand the world of why bad stuff happens. And I think that's related to the good and evil, but I think almost like just one rundown of complication.

52:22I also think in the case of Lyme, and maybe it's a good pivot to the chronic Lyme discussion, it lends itself well because of the origin story. Because the origin story is people were being ignored. A lot of the current discussion has focused on this question of like, is chronic Lyme.

52:40Emily Oster:Are people still being ignored? Are people still being ignored with this thing? And so to sort of have in the middle, it's not surprising that it's like we're being ignored. And also, by the way, this is the fault of, you know, this DOD scientist. So. All right. So let's turn to chronic Lyme disease. And I think we have to define our terms before we get too deep in this, because there are going to be people listening who are like, What are you talking about? So first of all, I will say that earlier I talked about late disseminated Lyme disease. So the Lyme disease, untreated Lyme disease that can cause joint swelling, heart problems, nerve problems, brain problems.

53:21Emily Oster:In some sense, that's chronic Lyme disease. You've had it for a long time, not years, but you've had it for whatever, a few weeks or something. It hasn't been treated and you get these diffuse symptoms. But that's late disseminated Lyme disease. That is not what we mean when we say chronic Lyme disease. Medically speaking, most people will refer to a syndrome called post-treatment Lyme disease syndrome, which is what it sounds like. You had Lyme disease, that was documented, it was treated, you're post-treatment, and you still have something wrong with you, which is not how this is supposed to go.

53:55Emily Oster:This is a bacterial infection. You should get antibiotics and be better. That's how these things are supposed to work. But post-treatment Lyme disease syndrome exists. We'll talk about what those symptoms can be. And we need to begin to understand how this weird bacteria can affect your body downstream even after it's dead. Chronic Lyme disease, though, is a catchier term than post-treatment Lyme disease syndrome. And not only encompasses post-treatment Lyme disease syndrome, people who documented Lyme, treated, still sick, but also a much larger group of people potentially without documented Lyme without a known tick bite sometimes who also have long-term symptoms.

54:36Emily Oster:And they can get caught up in this Lyme disease ecosystem for a variety of reasons, including the testing issues that we talked about. And the chronic Lyme disease ecosystem is filled with some very good practitioners who know a lot about infectious disease and Lyme disease and other tick-borne illnesses and some charlatans, unfortunately. And I think this space is so hard to talk about. It's so hard to talk about because there are many people who are genuinely suffering and who really deserve better answers and research. and there are also things that are being wildly oversold. And there's a balance between not wanting to say, you know, you are being oversold this thing, which is not going to fix your problems and saying you have no problems.

55:37And I think people hear you have no problems. This is all in your head. This is like a classic, like chronic anything, particularly for women here so frequently, this is all in your head, this is all in your head. And then people, it's not surprising that people would go out and search for someone who is going to take their very real concerns seriously. And this is why we actually need to see what the data says and why this deserves more research rather than being left to, you know, Charlottes who are taking advantage of people suffering.

56:07Emily Oster:Yeah, yeah, absolutely. So let me just talk about the symptoms. Yeah. Here's the problem. They're everything. There's a lot of different symptoms that are lumped into both post-treatment Lyme disease syndrome and chronic Lyme disease. Fatigue, brain fog, joint pain, intermittent rashes, gastrointestinal distress, psychological disturbance, depression, mania, psychosis. So hallucinations. And, you know, these can be debilitating. There are people who are unable to walk because of these issues. And yet, those are also symptoms that can occur from a lot of other diseases, including other infectious diseases.

56:49Emily Oster:And there is not a clear diagnostic test for either post-treatment Lyme disease syndrome or chronic Lyme disease. So we have a bad case definition. And one of the problems with, like, this comes up with the long COVID discussion a lot. I've criticized the case definition for long COVID because when a case definition isn't narrow, it actually becomes harder to study. And when people were making the case definition for long COVID, everyone was so concerned about having a big tent, right? Like it can be long COVID if you're tired. It can be long COVID if you have postural tachycardia syndrome. It can be long COVID if you have brain fog.

57:31Emily Oster:It was so diffuse that it actually was difficult to study because you look at biomarker differences in people with and without long COVID and like they all look the same. But the people with long COVID is this very heterogeneous group. So sometimes you actually want a case definition that's super tight, even if it'll exclude people from diagnosis so that you can actually figure out what the testing should be. And that wasn't done for long COVID. It wasn't done for chronic Lyme. Yeah, and I think in the case of chronic Lyme, you know, in some ways you would think, okay, so part of that should be, you know, tick bite and basic, like some evidence that you have had acute Lyme disease.

58:05But since our tests for this are potentially false positive, potentially we have a lot of false positives and potentially some false negatives. and because sometimes you get bitten by a tick and then you don't, it falls off and you don't know it, that actually can't be a, or at least that's not necessarily a perfect diagnostic criteria. So by leaving the tent open, we don't have a, we don't even have that, which would seem like the basic, the sort of first basic.

58:31Emily Oster:Yeah. And again, you know, the pathway for this is you start with a narrow case definition, then you get your diagnostic tests, then you expand those to other people without as classic symptoms, and then you can enlarge the tent. I said several times there's an ecosystem here, and I think what people need to be aware of is, okay, if you're in an ambiguous state, you don't remember a tick bite, you didn't have a rash, but you're feeling all these vague symptoms, you can get sort of funneled into, often through social media or through the internet, to a self-described group of practitioners called Lyme literate doctors.

59:09Emily Oster:And this is another term that's way too broad because there are, I know, plenty of infectious disease doctors who would call themselves Lyme literate. I mean, especially here in Connecticut, we have great infectious disease doctors who know everything there is about my giant table of tick-borne illnesses. Then there are sort of self-described Lyme literate doctors who are part of this almost like a more shadowy medical adjacent ecosystem. And the reason I keep saying ecosystem is because these doctors refer to each other. So there's a sort of circular nature there. These doctors send blood tests to specific labs, so sort of Lyme literate labs, which often lack FDA clearance and sometimes lack CLIA certification.

59:59Emily Oster:These labs will run tests that are research tests on the blood to look for evidence of Lyme disease, look for evidence of the spirochete, and often we'll find evidence. But again, we're very concerned about false positives because these are research tests and they set the thresholds for detection very low. There's a lot of cross-reactivity. And I've seen patients kind of get drawn into this. They start with vague symptoms, then they get a confirmatory test that tells them they have Lyme disease and they go down a treatment pathway, which can actually be quite dangerous. Again, this is not to say that they have real symptoms.

1:00:34Emily Oster:It's not even to say that they don't have Lyme disease. It's just not the safe path to obtain the diagnosis and get the right treatments. And there is a treatment that is very common and has been tested repeatedly and doesn't work. So the most common treatment for this is like IV antibiotics or very high dose. Long-term IV antibiotics. And, you know, there's a trial in the New England Journal of Medicine, which does not see any differences in health-related quality of life with people who are given, you know, long-term antibiotics versus a shorter course. And this is a long-term, I mean, people are on these antibiotics for like months at a time.

1:01:19Emily Oster:The risks of long-term intravenous antibiotics are quite, quite high. Just to say them out loud, you've got an indwelling catheter. So you've got to infuse it somehow, a PICC line, a central line of some kind. That's breaking the skin. So that increases the risk of skin-borne bacteria getting into your bloodstream and causing sepsis. You're getting antibiotics, which increases your risk for C. difficile, that bad diarrheal infection that happens when you kill off your good, healthy gut bacteria and the bad, evil bacteria take over. You dramatically increase your risk for candida infections. So yeast doesn't get killed by traditional bacteria.

1:01:53Emily Oster:bacteria, if you take an antibiotic, you're at high risk for yeast infections. But those yeast infections can happen in the blood in people with indwelling lines, and they're a disaster. I mean, they really are life-threatening. So this approach to therapy is super dangerous. And as you said, there's not just one randomized trial of this in chronic Lyme disease. There's multiple randomized trials. So some people got placebo, and some people got long-term intravenous antibiotics, and there's no difference in outcomes. It just doesn't work. And it's one of the red flags I have for people that are going through this and who are, you know, seeing a practitioner that's diagnosing them this way.

1:02:29Emily Oster:If they get to the point where they want to put a line in you and give you several months of antibiotics, that's really time to get a second opinion. I really think that's a red flag. And I mean, I think that the truth is, of course, there are people will say, well, I did this and it helped. Oh my gosh, look on Instagram. Yeah. And, you know, the placebo effect is a really, really powerful effect. That is why we need randomized trial data, and especially in a case like this where the potential downsides are very, very real, it is very important to make these decisions based on actual trial data.

1:03:02This is not taking a sugar pill and just using the placebo effect for its wonderful features. Yeah.

1:03:10Emily Oster:There's also some confirmation bias that I've seen happen. So you get your antibiotics and you feel better. Okay, great. That's confirmation that it worked. You get your antibiotics and you feel worse because you get diarrhea or one of the other many side effects from antibiotic use. There are people say, oh, that's the Jarish-Herxheimer reaction or the community calls it jerksing. This is a true thing. So any spirochete, for whatever reason, when you kill it with, so the other common one is syphilis. When you either kill syphilis or Lyme disease, acute Lyme disease with an antibiotic, the spirochetes lies and they release a lot of inflammatory stuff.

1:03:47Emily Oster:And for about 24 hours, you can get like fevers and chills and stuff. It's more commonly described in syphilis with initial treatment. So that happens in acute Lyme disease or can in a subset of people with acute Lyme disease. But there's no real reason to think it would happen in chronic Lyme disease because we can't isolate the bacteria. Like it's not like we can see the bacteria in your blood that's floating around. It's not there. You know, the tests don't show that. So it's not lysing. So, but what people will, they'll just attribute any negative symptom to jerksing and any positive symptom to getting better.

1:04:22Emily Oster:And it becomes this self-reinforcing thing. And by the way, here's another red flag. If you're seeing one of these practitioners, if they're not taking your insurance, okay, if you're paying out of pocket for this, these intravenous infusions can cost thousands and thousands and thousands of dollars. And I've seen patients who do it for three months. Maybe they feel better. They stop. They feel worse again. They do it for another three months, it can be really financially devastating. Yeah. I mean, I think the last thing I would just want to end on in this discussion, I don't think we're going to answer these questions, is people are going this route because the medical system has failed them.

1:04:59And so it's, I think, fine to say, it's reasonable to say, you know, you shouldn't go this route. But to just say you shouldn't go this route and whatever, so just live with it, is also terrible. And so I think there is real research that needs to happen. And I think some of it is happening. But real things that need to be done and people do need to be listened to. And if they were listened to, it would potentially close some of this distrust that exists.

1:05:28Emily Oster:Absolutely. Actually, just today I saw HHS had announced a series of new initiatives towards Lyme disease, including some research funding directed towards understanding these long-term post-treatment syndromes. That's good. Yeah. Ross Duthat, by the way, has a very good book called The Deep Places. Ross is a columnist for the Times who had chronic Lyme. And it's an interesting book to read because this is a very broadly scientifically minded person who really goes in directions that I think even he would say were very unscientific and experimental, just in a certain, and you can sort of feel the, like, I just need to figure out something to fix this because it is ruining my life.

1:06:09Emily Oster:Yeah. The desperation. The desperation. And doctors are, you know, I'll tell you from a physician standpoint, it's really hard to not be able to offer a patient something. You know, they come in and it's like, you know, they're having all this stuff and I can do these tests. And if I'm not coming up with anything, it feels is terrible. But the truth is, those are the places where research is most needed. And until that good, high-quality research is done, we are going to see a parallel ecosystem emerge. It's sort of the natural thing. People are going to offer solutions. And I don't want to discourage people from exploring any potential solution with the potential exception of long-term intravenous antibiotics because they really can be so harmful and potentially fatal.

1:06:59Emily Oster:So that's the only one that I really do worry about in this space. Otherwise, we just have to do better. Listen to your patients, work through. If you have to go symptom by symptom, go symptom by symptom, get them to the right specialists, figure out other mechanisms, other solutions to this. Okay. I want to end on a more positive note, which is about the vaccine. So a lot of people, specifically my husband, asked me three times a week why there's no Lyme disease vaccine, because he hates dicks. My dog gets a Lyme disease vaccine. Your dog gets one. And amazingly, we used to have one. So there was a Lyme disease vaccine called Limerick's, which was pulled off the market in 2002.

1:07:44It did work. There was a litigation backdrop. People said there were autoimmune side effects. They just decided it was not worth it. I don't think it made enough money, honestly. People didn't want it. But it's back. Not that, but something else. There's a new Lyme disease vaccine that just completed its trial in March. 73 % efficacy against infection. The confidence interval is enormous. 16 to 93%. Very big. Not enough people in your trial. Not a lot of cases of Lyme. Because there weren't many cases. But, you know, it seems like we are moving in the direction of having this. So, Jesse, hopefully soon for you, Lyme disease.

1:08:23And let me say one other thing before we smash or pass our ticks, which is you should be avoiding ticks. Moving away from Lyme disease, you want to avoid ticks. Yeah, yeah. Let's not even get started. Okay. So there are two things about avoiding ticks. One is there's stuff. It comes in an orange spray bottle. You can spray it on. It's called permethrin.

1:08:42Emily Oster:Oh, permethrin. Permethrin. Yeah. And you can spray your clothes with it. That's a really good idea if you're going to be hiking in tick-borne areas because it, like, repels the ticks off your clothing. okay that's a really good idea yep bug spray also works uh deed is fine it's not poison you can use it also perfects you against mosquitoes and you should check people for ticks in your family you should check each other for ticks it's not going to fix your powassan problem but for lime taking ticks off if you see them is good and so you should check yourself there's also a really good country song um with that lyric check yourself for ticks no it's like i want the The lyric is, I want to check you for ticks.

1:09:22Oh, okay. And, you know, it's romantic. Yeah, I guess so. Foreplay.

1:09:27Emily Oster:Sure. Primates do groom each other. All right, Perry. Are you a smash or pass on ticks? I'm going to pass on ticks. I think you should stay away from them. I think they should stay away from us. You know, I don't know. Ecologically, do they have some role? I, you know, like if I could snap my fingers and eliminate all ticks, would it cause some horrible, like would then all of a sudden, like all the ducks would die? I don't know. But yeah, pass. How about you, Emily? I'm a pass on ticks. Yeah, I'm a pass on them. That's very controversial. Controversial. Controversial take. Don't like ticks. All right.

1:10:09Emily Oster:When we come back, your question of the week. Remember the 90s, the golden age of snacks? Simple Mills does. Simple Mills brings back that unmistakable throwback taste with favorites like cheddar pop-ums, mini crunchy chocolate chip cookies, and honey cinnamon sweet thins. Only now, they're made with thoughtfully chosen ingredients like watermelon seed flour, cashews, flaxseed, and organic coconut sugar. Available in snack packs that your inner 90s kid would have begged for. With ingredients your grown-up self can appreciate. Simple Mills, throwback taste. Grown-up ingredients. I thought I looked so cute.

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1:12:02Emily Oster:This is according to Ooglu Speed Test Intelligence. Date a second half of 2025. All rates reserved. Redeemed money back guarantee within 30 days of cancellation. And we're back with our question of the week. If you have a question for us, drop us a line at wellnessactually.fm. Our mailbag question of the week is here. Hey, Emily M. Perry. This is Nate from Arkansas. Simple question. Is VO2 max a good indicator of overall health? Thanks. Okay, Emily, VO2 max. This is right down the middle for an Emily Oster question. What is VO2 max? What do you think my VO2 max is? What is your VO2 max? And how good is it as an indicator for overall health?

1:12:50Amazing. Okay. So VO2, I'm made for this question. So VO2 max is the highest amount of oxygen that your body can use during hard exercise. So it is a measure of how well your heart and lungs and muscles working together. So the V is volume, O2 is oxygen. So max means the maximum. So it is a common metric of like aerobic fitness. Higher is better. Higher is better. Higher is better. It goes down with age. And the reason this gets a lot of attention is if you ran a regression, like an analysis of like – so looked at correlations between longevity and many other – many metrics you would have, this loads the strongest.

1:13:38So this is like the highest value predictor of things like longevity that we have. Interesting. Yeah. And overall health and everything. Beats grip strength, beats BMI or whatever. It beats like finger strength, although finger strength, we can get another episode how stupid that is. But this is really, it beats, you know, resting heart rate. It beats like BMI. Like it's really, really good. And so what people like to interpret that as like, you know, if I changed this, it would be really beneficial. I think that that's too far. I think the issue is that this is something that moves very readily with a lot of the kinds of behaviors we know are effective.

1:14:18So this is something you can move pretty easily with exercise. And so even when people who don't exercise at all exercise for small amounts, you will already move their VO2 max. And so it's just like a very sensitive measure. And so that's why the correlation is so good. And so there are many things that you could do to move this, which would probably be good for you. But like if just one day you woke up and nothing else had changed and all of a sudden your vo2 max was higher like that's probably not meaningful um what's a good number how do i measure it yeah so if you have a wearable it will measure it will give you a kind of correlationally appropriate but noisy and kind of garbage like but like your wearable will measure this if you really want to measure this like you're in the you know cycling or whatever yeah uh you got to get on a like you get on a on a treadmill with a mask on and then you like run to exhaustion and that will measure your vo your vo2 max don't threaten me with a good time people don't really people don't really do that there's no reason to do that um but if you have a wearable the like and you start exercising more this is a number of people will see move it's like a good motivator i would guess yours is

1:15:33Emily Oster:like 45 ish okay what's yours 55 oh all right that's fine i don't really know what that means but i'm flattered that you you're gonna give me 90 percent yeah uh it's like the you know truly like exceptional elite athletes will be in like the 80s but that would be like very unusual the sort of average for people is in the like 30s have you done the full mask no i didn't i i did consider it, but I had trouble finding a lab because I'm crazy. And I ultimately decided there was no point in knowing that number except to say it on a podcast. And to just assert that you're 10 points higher than I am.

1:16:10Now I'm regretting it. But I was able to assert that I was 10 points higher than you with no evidence.

1:16:16Emily Oster:Emily and I are doing a VO2 max competition. I will probably die.

1:16:23Emily Oster:That's it for us today. We are actually off next week. We'll be rerunning a classic episode. It's definitely worth a listen. Enjoy the end of the summer. It was great to see you in person today. And I want to thank the audio engineer here at Yale, Ryan McAvoy. Thanks, Ryan. Wellness Actually is produced in association with iHeart Media. Our senior producer is Tamar Avishai. Our executive producer at iHeart is Jennifer Bassett. Our theme music is by Eric Deutsch, and our content is for educational purposes only. If you like the show, help other people find us. Leave a rating and review on Apple Podcasts or your podcatcher of choice.

1:17:01Emily Oster:And help us spread the word about the show. You can follow us on Instagram at wellnessactuallypod. And don't forget, we want to hear from you. Head over to wellnessactually.fm and leave us a question for our mailbag or suggest a topic for a future show. We'll let the influencers have the last word. You see, class, my Lyme disease turned out to be psychosomatic. Does that mean you're crazy? No, that means she was faking it. No, actually, it was a little of both.

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