Speaker 1: Hello, friends, We're talking about parasites again today. These parasites
Speaker 1: can have some pretty nasty impacts on human bodies, and
Speaker 1: I just wanted to give you all a heads up
Speaker 1: in case you or your kiddos are a bit squeamish
Speaker 1: about such things. I study parasites for a living, so
Speaker 1: I am a long past having a reasonable handle on
Speaker 1: what a decent person would consider disgusting. Sorry about that, Okay,
Speaker 1: on with the show. In eighteen ninety eight, a German
Speaker 1: parasitologist named Arthur Loss was trying to figure out exactly
Speaker 1: how this particular kind of parasite infects people, as was
Speaker 1: fairly common at the time. The method he was using
Speaker 1: to try to figure out this parasite's complicated life cycle
Speaker 1: was by trying to infect himself in various ways. During
Speaker 1: this self experimentation, he discovered something surprising. He was already
Speaker 1: infected by a different parasite species. How did you make
Speaker 1: this discovery? Well, it's kind of a gross story. You see.
Speaker 1: He knew that the parasite he was initially studying lives
Speaker 1: in our guts and produces eggs that get out of
Speaker 1: the body by traveling out in our bowel movements. So
Speaker 1: when he was checking his turns for parasite eggs, he
Speaker 1: found the eggs from this other species. The kind of
Speaker 1: parasite he discovered he was infected with is commonly called
Speaker 1: a hookworm, and this was another species of parasite for
Speaker 1: which back in eighteen ninety eight we had figured out
Speaker 1: how it manages to infect people in the first place.
Speaker 1: So Low starts thinking back on behaviors he had engaged
Speaker 1: in recently to get a good guess for how he
Speaker 1: got infected with this parasite. His best guess was that
Speaker 1: maybe it accidentally happened during an experiment that he was
Speaker 1: doing on hookworms and guinea pigs where he accidentally spilled
Speaker 1: some of the hookworms on his hand. He remembered afterwards
Speaker 1: that he started scratching like crazy and that it was uncomfortable,
Speaker 1: and he thought, well, maybe the parasites get through your skin.
Speaker 1: No stranger to self experimentation. Los subsequently dropped some more
Speaker 1: juvenile hookworms on his hand and his skin started to
Speaker 1: burn and get red. Then he tried to like scrape
Speaker 1: his skin a little bit to see if he could
Speaker 1: get the worms off there, and he noticed that there
Speaker 1: were far fewer worms on that scrape than he had
Speaker 1: initially put on his hand, so he suspected, Okay, they're
Speaker 1: actually disappearing into my skin. So he's feeling pretty good
Speaker 1: about his hypothesis now that the parasites get in by
Speaker 1: burrowing through your skin. But how could he know for sure? Well,
Speaker 1: Los finds himself a volunteer, a young man who was
Speaker 1: in need of a leg amputation, graciously agreed to help
Speaker 1: out with science. In the process, Los put some of
Speaker 1: the juvenile hookworms on the leg of the patient prior
Speaker 1: to the procedure. Following the imputation, Los was able to
Speaker 1: recover the parasites that had indeed burrowed through the skin
Speaker 1: and were working their way through the leg. So now
Speaker 1: he knew that hookworms infect people by getting their eggs
Speaker 1: into the environment with our poop, and then the juvenile
Speaker 1: worms hatch out and go off in search of things
Speaker 1: like bare feet. Knowing how a parasite affects you gives
Speaker 1: you some tools to help combat the parasites. Flash forward
Speaker 1: about ten years and John D. Rockefeller is using his
Speaker 1: oil money to create a commission to do battle with
Speaker 1: this parasite in the American South. Today, we're making some progress,
Speaker 1: but we still have a long way to go. Improved
Speaker 1: sanitation systems have made this parasite rare in the United States,
Speaker 1: but globally this parasite and a few other species that
Speaker 1: will also talk about in this episode. Improve sanitation systems
Speaker 1: have made this parasite rare in the United States, but
Speaker 1: hookworms and some other parasites that you find in the
Speaker 1: soil are still a problem in other parts of the world.
Speaker 1: This parasite infects about one and a half billion people worldwide,
Speaker 1: or about twenty five percent of the global population, though
Speaker 1: the infections are mainly happening in Asia and Africa. Today,
Speaker 1: we'll talk more about these parasites and how public health
Speaker 1: officials are currently trying to do battle with this ancient
Speaker 1: scourge of humanity. To Daniel and Kelly's extraordinarily warmy universe.
Speaker 2: Hi, I'm Daniel. I'm a particle physicist, and I contain multitudes.
Speaker 1: Hi. I'm Kelly Wiener Smith. I study parasites for a living,
Speaker 1: and I agree Daniel does contain multitudes. I do too.
Speaker 1: We all do. You're never alone.
Speaker 2: There's a side of me that's fascinated by biology, and
Speaker 2: then the side that thinks it's totally griss.
Speaker 1: You know, I let both of those sides coexist inside myself.
Speaker 1: It's okay to be grossed out by something but still
Speaker 1: think it's fascinating.
Speaker 2: You're a quantum superposition of biological fascination.
Speaker 1: I don't think they have to be diametrically opposed, like
Speaker 1: the cat's alive the cat is dead. I think it
Speaker 1: can be both awesome and disgusting. They're not mutually exclusive states.
Speaker 2: You never have that moment where you're like looking at something,
Speaker 2: You're like, Wow, this is fascinating, and then all of
Speaker 2: a sudden you get the ick, like, WHOA, I can't
Speaker 2: touch this thing anymore. I have to put it down.
Speaker 1: No, but there was a moment in a talk. It
Speaker 1: was an anthropology talk that grossed me out. There was
Speaker 1: a table of monkey brains. It was that a food market,
Speaker 1: and even though I had just spent like literally the
Speaker 1: last couple months looking at fish brains and thought that
Speaker 1: I was like totally immune to brain related disgustingness, the
Speaker 1: room started to spin and I had to put my
Speaker 1: head down because looking at the monkey brains was making
Speaker 1: me sick, and I was so embarrassed. I was like,
Speaker 1: I should be okay, but what about you. What was
Speaker 1: the moment where disgust just sort of overwhelmed you. I
Speaker 1: imagine that being married to Katrina, there's gotta be a
Speaker 1: lot of like hope related moments.
Speaker 2: Well, you know, there are times when I expected to
Speaker 2: be grossed out, Like, for example, when my daughter was
Speaker 2: born by sea section, and they told me you have
Speaker 2: to sit behind the curtain, you can't watch, and I
Speaker 2: was like, oh no, I'm looking at this. And I
Speaker 2: stood up and I peeked over the curtain and I
Speaker 2: was totally fine, like, ow, that's my wife and they're
Speaker 2: cutting her open, and that's my daughter, and it's pretty goofy.
Speaker 2: But it was just so amazing. Yeah, I didn't fainter,
Speaker 2: cost trouble or anything. Missed that moment, and then you know,
Speaker 2: much more simply, there's the time when I like, open
Speaker 2: the freezer in our house, I'm like, what's in this
Speaker 2: paper bag? Uh? Oh no, that's not what I expected.
Speaker 1: It's a sample that's pretty gross. You know. It's funny
Speaker 1: I didn't get a C section, but my husband couldn't
Speaker 1: even look on the other side of the curtain over
Speaker 1: the legs because he was just like, no, no, this
Speaker 1: is all too gross. And they went to lift the
Speaker 1: umbilical cord up, like do you want to cut the
Speaker 1: And before they even got it up over the blanket,
Speaker 1: he was like, no, no, just hand me the dry
Speaker 1: clean baby, please. I don't need to know any of
Speaker 1: this stuff. And he did a good job providing support
Speaker 1: from the safe side of the blanket.
Speaker 2: Well. Biology is messy and squishy, but that's how life works, right, reproduction, propagation,
Speaker 2: all of that stuff. And something that I've had to
Speaker 2: come to terms with, especially being married to Katrina and
Speaker 2: learning more about microbes, is that inside all of us,
Speaker 2: it is a whole ecosystem. It's not just human cells
Speaker 2: that make you work. You are filled with all sorts
Speaker 2: of bacteria and other stuff, some of which are vital
Speaker 2: to the operation of your guts and some of which
Speaker 2: are doing you harm. And the line between them can
Speaker 2: be a little bit fuzzy, isn't that right?
Speaker 1: Yeah, it really can. So the parasites that we're going
Speaker 1: to be talking about today, there's some evidence that when
Speaker 1: you have just a few of them, they help suppress inflammation,
Speaker 1: or the presence of these parasites suppresses inflammation, and maybe
Speaker 1: even having some of these parasites reduces your risk of
Speaker 1: allergies or some autoimmune diseases. So yeah, that's not necessarily
Speaker 1: yes or no dichotomy sort of here. It sometimes it's
Speaker 1: a gradient. It's complicated.
Speaker 2: Yeah, it's not something we can understand from first principles
Speaker 2: because the body is a huge complex Rube Goldberg machine, right,
Speaker 2: and you can't look at it and say, if I
Speaker 2: pulled this one thing out, everything would be better or worse,
Speaker 2: Like it would be different, and it's not always clear
Speaker 2: whether it's better or worse. So is it even clear
Speaker 2: what a parasite? I mean, if we're going to talk
Speaker 2: about parasites in humans that date back thousands of years,
Speaker 2: you know, maybe they're just part of how we evolved.
Speaker 1: Yeah, so parasites definitely are part of how our species evolved,
Speaker 1: that they've been with us, you know, from the beginning.
Speaker 1: But then the question is do they do more harm
Speaker 1: than good? And I think the answer really depends on
Speaker 1: context and even can depend on the person how their
Speaker 1: immune system responds to these parasites. And so I think
Speaker 1: it's never a yes or no. Although with the parasites
Speaker 1: we're gonna talk about today, when you have a lot
Speaker 1: of them, that is always bad. There is zero debate
Speaker 1: about whether or not it's bad to have a lot
Speaker 1: of these parasites. It is, and unlike tricinella, which we
Speaker 1: talked about last week, where there's been a lot of
Speaker 1: progress made around the world, but particularly in places like
Speaker 1: the United States, for controlling the transmission of this parasite
Speaker 1: and making sure pretty much no one gets it. These
Speaker 1: soil transmitted nematodes. And I think Daniel's gonna tell me
Speaker 1: that's too much jargon. So we're gonna call them dirt worms.
Speaker 2: Oh I love it, dirt worms, thank you.
Speaker 1: Yes, these nematodes, which are these like long, thin, cylindrical parasites,
Speaker 1: we're gonna call them dirt worms because they're a wormy shape.
Speaker 1: These are still a problem in some parts of the
Speaker 1: United States, in particular areas that are poor and don't
Speaker 1: have good sanitation, and they are a problem in Africa
Speaker 1: and Asia. It's thought that about twenty five percent of
Speaker 1: the world's population is infected with at least one of
Speaker 1: these worms, and a lot of people are infected with
Speaker 1: a lot more than that.
Speaker 2: I guess some of the questions we'll be asking today
Speaker 2: is how long we've been doing battle or evolutionarily dancing
Speaker 2: with these dirt worms, whether they hurt or help us,
Speaker 2: and what we can do about them in the future.
Speaker 1: Right, Yeah, So let's just jump right in. So you know,
Speaker 1: you asked, like, how long have we been doing battle
Speaker 1: with these parasites and the answer is a really long time.
Speaker 1: So there's some evidence from the ancient Nile Valley. So
Speaker 1: like when the ancient Egyptians were, you know, ruling the
Speaker 1: world or whatever, they were infected by some of these worms.
Speaker 1: And the way that we figure it out is again
Speaker 1: creepy but wonderful, like both those things together. So we
Speaker 1: study what are called coprolites, which is essentially like poop fossils.
Speaker 2: Poop fossils, oop fossils.
Speaker 1: Yes, I have such a big grin on my face,
Speaker 1: and so they are like parasite eggs that you can
Speaker 1: still like dig out of these poop fossils. In some
Speaker 1: cases you can extract a little bit of DNA from
Speaker 1: them to confirm. But the eggs from the different kinds
Speaker 1: of dirt worms that we're gonna be talking about today
Speaker 1: are pretty distinctive.
Speaker 2: Let's go back to what these things are. Are these
Speaker 2: things we find like in the guts of mummies or
Speaker 2: in ancient toilets, or where are we finding these poof fossils?
Speaker 2: How do we know that they're poof fossils and not
Speaker 2: just lumps of dirt?
Speaker 1: Well, all of the above. So sometimes we'll find like
Speaker 1: a latrine, and so like it's kind of clear from
Speaker 1: what's happening around the samples the specimens that it was
Speaker 1: like a latrine, and so there'll be a bunch of
Speaker 1: poop in one place. Sometimes you'll find a mummy, and
Speaker 1: if you dig around in the mummies intestines, some of
Speaker 1: the parasite eggs that we're passing through the body of
Speaker 1: that mummy are still there. You can look there, or
Speaker 1: if you've got like a body that's sort of decomposed,
Speaker 1: you can dig around in the dirt around where they're
Speaker 1: like belly and their bells were, and sometimes you can
Speaker 1: still find parasite eggs that have been preserved in that area.
Speaker 2: Preserved how like if you put them in water, they
Speaker 2: would like swiggle back into worms like tartar grades, or
Speaker 2: they're like fossils of these eggs. Because fossilization is some
Speaker 2: process we are replacing it with minerals, right, So what
Speaker 2: it actually is preserved here.
Speaker 1: Yeah, it's mineralization, so they're definitely not coming back to life.
Speaker 1: Mineralized parasites sometimes with a little bit of DNA still present,
Speaker 1: but like you really have to worry about contamination. It's
Speaker 1: hard to do the DNA stuff, but we can be
Speaker 1: pretty sure.
Speaker 2: You know, some of these ancient kings really wanted to
Speaker 2: be remembered in the future, and I wonder how they
Speaker 2: would feel about, you know, this is what they've passed
Speaker 2: down to later generations.
Speaker 1: If you managed to get in one of those pyramids
Speaker 1: and you really didn't want anyone to disturb you, you're
Speaker 1: probably not super happy if this is happening. But yeah,
Speaker 1: that's the uncomfortable history of science.
Speaker 2: Speaking of the history of science, we know a lot
Speaker 2: about ancient Egyptian culture, and we have their hieroglyphics. Is
Speaker 2: there any evidence in their writing that they understood what
Speaker 2: was going on in their guts? Like, were there ancient
Speaker 2: Egyptian parasitologists.
Speaker 1: I don't think there were ancient Egyptian parasitologists. There are
Speaker 1: some writings, I think in Chinese texts where it's interpreted
Speaker 1: that they were talking about some of these worms, but
Speaker 1: we don't know for sure, so you know, the description
Speaker 1: would just be like there was a wormy thing, and
Speaker 1: you're like, well, that could be a lot of things,
Speaker 1: because we're infected by a lot of wormy things, especially
Speaker 1: a long time ago. There's some guesses that like ancient
Speaker 1: Chinese texts were talking about roundworms, so these very long,
Speaker 1: like pencil sized worms. But I'm not an expert in
Speaker 1: this topic, and I'm under the impression that the best
Speaker 1: we can do is, oh, that's probably right ascharis for example,
Speaker 1: But we don't know for sure.
Speaker 2: So then how far back do these fossils go, Like
Speaker 2: how long have we been living with these worms?
Speaker 1: The review paper that I was reading talked about copper
Speaker 1: lightes so fossilized poop that had evidence of parasites from
Speaker 1: Krueger Cave in South Africa that was twelve thousand years
Speaker 1: before present, so twelve thousand years ago.
Speaker 2: Wow.
Speaker 1: And that mummy Utzi, how do you say, do you
Speaker 1: know the name of that mummy? The one that was
Speaker 1: found in the Alps near Italy and Australia, and I
Speaker 1: think it had like a arrowhead.
Speaker 2: Let's see the iceman.
Speaker 1: Yeah, yeah, the iceman. The iceman had whipworm and is intestine.
Speaker 1: Oh wow, this has been a problem for a lot
Speaker 1: of people for a long time.
Speaker 2: Do you think it's possible that we had worms before
Speaker 2: we were humans, Like, had they evolved with us from
Speaker 2: our ancestors or was there a time when we were
Speaker 2: first infected and before that our ancestors were a worm
Speaker 2: free somehow? What do you think is more likely?
Speaker 1: Yeah, I think our ancestors had these worms, and the
Speaker 1: worms probably speciated with us. I can't say that I've
Speaker 1: actually looked up the phylogeny of the nematodes and the
Speaker 1: ascarids and the parasites we're talking about today, but folks
Speaker 1: have done this kind of work, and there are a
Speaker 1: lot of parasites that our ancestors had, and the parasites
Speaker 1: speciated along with our ancestors and us, and so you
Speaker 1: ended up with like two sort of human e species
Speaker 1: and two you know, parasites to infect both of them.
Speaker 2: Wow. I think that goes a long way to making
Speaker 2: the argument that it's part of being human is to
Speaker 2: have worms, because we've always had them, right, Like, literally
Speaker 2: the first humans had worms. So it's maybe what it
Speaker 2: means to be human is to be a little bit wormy.
Speaker 1: I think what it is to be alive is to
Speaker 1: be a little bit wormy or to be a little
Speaker 1: bit infected. I think you know just about any wild
Speaker 1: animal that you go pick up in nature, if you
Speaker 1: dissect it, it's got probably a nematod, maybe a treematod.
Speaker 1: It's probably got some lice. Parasites are ubiquitous.
Speaker 2: So what fraction of our listeners hearing this right now
Speaker 2: do you think have worms inside them?
Speaker 1: Really depends on where they're listening from. I think you
Speaker 1: and I probably don't have worms. I might have toxoplasmosis
Speaker 1: because I have barncats and I regularly interact with their
Speaker 1: feces while I'm cleaning stuff up. But I think you know,
Speaker 1: if you cook your food well and you live in
Speaker 1: a pretty sanitary environment, you can escape a lot of
Speaker 1: this stuff.
Speaker 2: All right, So we've been living with worms forever. It's
Speaker 2: part of being human, part of being alive, part of
Speaker 2: existing in this wonderful, squishy world. Tell us about how
Speaker 2: these things live, like, did they just hang out in
Speaker 2: your guts? Is there some whole process where they go
Speaker 2: in and out of you? Do they move from person
Speaker 2: to person? What's the whole life cycle of these crazy worms.
Speaker 1: Yeah, so for this set of worms and for a
Speaker 1: bunch of other parasites also, they live in our guts
Speaker 1: and they produce eggs that pass with our feces into
Speaker 1: the environment, so they're not multiplying inside of us. Each
Speaker 1: parasite that we have in us we accidentally independently, like
Speaker 1: consumed from the environment, and then their eggs go with
Speaker 1: our feces out into the environment, where if we don't
Speaker 1: take good care of our feces and we don't have
Speaker 1: good sanitary procedures, then they can go off and infect
Speaker 1: other people.
Speaker 2: Oh so, if you have worms, you can get rid
Speaker 2: of them by just stop eating worms.
Speaker 1: Well, I mean the worms that you have in you
Speaker 1: can survive for a while.
Speaker 2: Oh I see.
Speaker 1: I think the three that we're talking about today have
Speaker 1: an average lifespan of about a year, but some of
Speaker 1: them can live much longer than that. So if you
Speaker 1: stop accidentally ingesting parasites and you can go a year
Speaker 1: without reinfecting yourself, then you can get rid of these parasites.
Speaker 1: But a problem is that there's lots of places in
Speaker 1: the world where sanitation is not very good, and so
Speaker 1: you know, humans will defecate out into the environment, and
Speaker 1: then the feces will sort of dry, and the parasites,
Speaker 1: you know, by getting on people's feet who are walking
Speaker 1: around in the like latrine area, they'll spread out into
Speaker 1: the environment. The way the dirt worms work, and there's
Speaker 1: something like four different species of these dirt worms, is
Speaker 1: that the eggs get in the environment, and then the
Speaker 1: eggs after like waiting a short period of time, if
Speaker 1: they get into you because you like maybe you were
Speaker 1: gardening in an area where there was night soil, so like,
Speaker 1: those feces may have actually been placed on top of
Speaker 1: your plants as a way to fertilize them, and so
Speaker 1: if you don't wash them well enough or wash your hands,
Speaker 1: you could accidentally ingest the eggs and get infected that way.
Speaker 2: Did you just use night soil as a euphemism for poop?
Speaker 1: Uh? No, that's a great question. No. Night soil is
Speaker 1: the like technical term for the use of human and
Speaker 1: livestock waste as fertilizer. This is actually pretty common in China,
Speaker 1: which is one of the reasons why China has problems
Speaker 1: with some of these parasites. Oh, you can treat the
Speaker 1: night soil and kill the parasites in it before you
Speaker 1: use it, but that doesn't always happen, and so that
Speaker 1: spreads the parasite like crazy.
Speaker 2: And how big are these eggs? Like they must be
Speaker 2: very small, otherwise you would notice them and avoid eating them. Right,
Speaker 2: we're not talking chicken eggs here obviously, Like we're talking microscopic.
Speaker 1: Yeah, microscopic. You can't see them with the naked eye.
Speaker 1: You got to put them under a microscope to see them.
Speaker 2: Oh wow. So they're like under your fingernails and stuff.
Speaker 1: Yeap, like pinworms. So the dirt worms are round worms,
Speaker 1: which are you know, round, and they get pretty big,
Speaker 1: like I dissected one in class, Like they're big enough
Speaker 1: that you can dissect them. They're like pencils, like they
Speaker 1: can be about a foot long, and they're thick. And
Speaker 1: after you see them, you are like, I'm not eating
Speaker 1: spaghetti for a really long time, Like I.
Speaker 2: Just put see you got the ick?
Speaker 1: I did get the ick? Yeah? No, asparants give me
Speaker 1: the egg. Roundworms are super inchy. And then there's whipworms
Speaker 1: and they're called that because like they have tails that
Speaker 1: kind of look like whips, but they're much much smaller.
Speaker 1: You know, a big one is like fifty millimeters and
Speaker 1: then there's hookworms. And so hookworms they get into you
Speaker 1: in a totally different way. So they get to pop
Speaker 1: it into the environment, and then their eggs hatch and
Speaker 1: they release these tiny little juvenile stages, and the juvenile
Speaker 1: stages they go up on the grass and stuff, and
Speaker 1: as you walk past, they get on your skin and
Speaker 1: then they burrow into you. Yeah, and it often itches
Speaker 1: and is uncomfortable.
Speaker 2: Get big timech over here, I know.
Speaker 1: I'm sorry, I'm sorry. But they take the wildest journey
Speaker 1: to get to your gut. And I'm gonna tell you
Speaker 1: all about it when we get back from the break.
Speaker 1: So hookworm goes on this crazy journey once it gets
Speaker 1: into your body. All right, So it burrows in like
Speaker 1: you know, you're walking around, it's a beautiful morning, there's
Speaker 1: dew on the grass. But accidentally you encounter a hookworm
Speaker 1: and it burrows in, you know, between your toes or something,
Speaker 1: and it ends up in your circulatory system.
Speaker 2: Can it dig in anywhere? Does it have to find
Speaker 2: some soft spot between your toes?
Speaker 1: It can dig in anywhere? Oh wow, yeah nasty. And
Speaker 1: so it goes into your circulatory system and it rides
Speaker 1: it till it gets to your lungs, and then it
Speaker 1: goes out of the circulatory system into your lungs into
Speaker 1: your lungs. Well, it gets worse, I think it gets worse.
Speaker 1: And so then it crawls up your lungs and it
Speaker 1: crawls up and it gets into like sput them. And
Speaker 1: so when you like kind of cough, you cough up
Speaker 1: the parasites. And then when you swallow that again it
Speaker 1: goes into your stomach.
Speaker 2: You cough up the worms into your mouth, so now
Speaker 2: you like have warmy mouth.
Speaker 1: I know this is really rise.
Speaker 2: We are tilting far from curiosity towards icky again.
Speaker 1: I feel like those things are connected. But I've got
Speaker 1: a friend named Jimmy Burnout who got purposefully infected for
Speaker 1: a vaccine trial, and you know, like I wanted to,
Speaker 1: you know, like when you spit up, can you feel
Speaker 1: the worms in your mouth? And he's like, no, no,
Speaker 1: like they're really small. I think it was on his
Speaker 1: mind every time. He was like, eh, you know, he
Speaker 1: probably thought to himself like, oh, those are worms, but
Speaker 1: he said it wasn't like obvious. So anyway you swallow them,
Speaker 1: they get into your gut. But hookworms cause trouble because
Speaker 1: they eat your blood. So they have these like hooky mouths,
Speaker 1: and they use those hooks to like cut into the
Speaker 1: sides of your intestine and they suck blood out that way,
Speaker 1: and then they'll move on to a different site. And
Speaker 1: so often you will end up with like a lot
Speaker 1: of blood in stool, blood in poop if you have
Speaker 1: too many of these, because they've just opened up a
Speaker 1: bunch of wounds in order to get at your blood.
Speaker 2: So why did they go into your intestine to eat
Speaker 2: your blood If they started out in your circulatory system,
Speaker 2: why aren't they just like happy floating in blood.
Speaker 1: So I think that it has to do with the
Speaker 1: ease of getting your eggs back out into the environment.
Speaker 1: You make eggs and you just release them into the intestine,
Speaker 1: your body will just you know, with the rest of
Speaker 1: your food and with the rest of your bowel movement,
Speaker 1: just move it back out into the environment, and that
Speaker 1: way their eggs can get back out inside of the world.
Speaker 1: The real question to me is there's this other parasite
Speaker 1: called roundworm's ask Chris. These are the ones that are
Speaker 1: like pencil shaped. You eat them accidentally.
Speaker 2: With a nice tomato sauce.
Speaker 1: Maybe who knows, if you didn't wash your hands before
Speaker 1: preparing the tomato sauce. Maybe, but then they go like
Speaker 1: into your digestive tract. But then they burrow out of
Speaker 1: your stomach and into your bloodstream and do the same
Speaker 1: lung spit up, get back to your gut thing. And
Speaker 1: so I wrote an expert who works on hookworm vaccines
Speaker 1: and who studies this stuff, and his name's John Hawden,
Speaker 1: and I was like, John, why does Askris go on
Speaker 1: that long journey when it had already gotten to where
Speaker 1: it wanted to be? And he pretty much was like,
Speaker 1: we don't know. One of the hypotheses is that it
Speaker 1: evolved from an ancestor that already made that journey and
Speaker 1: so just sort of like evolution left that step in.
Speaker 1: Whether that makes sense or not, there's another argument that
Speaker 1: they need some extra time to develop, and going through
Speaker 1: this journey gives them a little bit more development time. It's
Speaker 1: not clear to me why they can't just stay in
Speaker 1: the gut and finish their development there. But maybe, like
Speaker 1: you know, you get intestinal cells slough off, you got
Speaker 1: some risk of being pooped out accidentally, And so the
Speaker 1: answer is, we don't really know, but it could be
Speaker 1: like a relic of what some ancestor used to do
Speaker 1: that kind of stuck with this parasite.
Speaker 2: Maybe it's the friends they make along the way, you know.
Speaker 1: That's right, that's right. They wanted to hang out with
Speaker 1: the other lungworms for a while, and you'd hate to
Speaker 1: lose your buddies.
Speaker 2: How long have we known this kind of stuff? Like
Speaker 2: we know that people have been having worms forever, When
Speaker 2: did we first start to understand this stuff? When is
Speaker 2: the science of worminess really kick off?
Speaker 1: Well, so for hookworms, which I know the most about,
Speaker 1: around eighteen forty there was a doctor Debinni who was
Speaker 1: doing dissection of a cadaver like a post mortem examination,
Speaker 1: and he found hookworms and wrote about it. So he
Speaker 1: was one of the first ones to be like, oh,
Speaker 1: like this might be something we should look into more.
Speaker 1: And then in eighteen fifty four, Wilheim Greysinger, sorry about
Speaker 1: the mispronunciations everyday, did a post mortem on a soldier
Speaker 1: and this guy had a lot of worms. And this
Speaker 1: was the first time that somebody was like, you know what,
Speaker 1: this worm could be bad enough that maybe this is
Speaker 1: part of why the soldier died. Because the soldier had
Speaker 1: like really awful diarrhea. So that was the first instance
Speaker 1: that we know of where somebody was like, not only
Speaker 1: are these worms in there, but they could be the
Speaker 1: cause of a problem.
Speaker 2: And do you think the earlier discovery of worms in
Speaker 2: the body was a surprise or is this something people
Speaker 2: were sort of genuinely aware of, like, yeah, people have
Speaker 2: worms in them, or it was like, oh my god,
Speaker 2: there are worms in people's bodies.
Speaker 1: I think we knew about it before then. I think
Speaker 1: the ancient Greeks knew about some of these worms. I
Speaker 1: don't actually know how well substantiated this is, And at
Speaker 1: some point I'd love to have a whole episode on
Speaker 1: guinea worms. But you know how doctors have that staff
Speaker 1: with like the two snakes that sort of wrap around it,
Speaker 1: and that's like this ancient symbol. There's some evidence that
Speaker 1: that was the guinea worm parasite, because the way you
Speaker 1: eradicate that parasite is you wrap it around a stick
Speaker 1: and you sort of slowly extract it from people because
Speaker 1: it sticks its head out of your ankle. Oh that nasty,
Speaker 1: But actually that's another success story. We're like close to
Speaker 1: eradicating that one. That one's pretty interesting. They're all pretty interesting.
Speaker 2: Really, and we want to eradicate them because some of
Speaker 2: them obviously cause harm or you have too many of them.
Speaker 2: I mean, somebody like a train it might say like, hey,
Speaker 2: why are we calling these things pathogens? They're just part
Speaker 2: of the human life cycle.
Speaker 1: Hmm. The personal line in the sand that I use
Speaker 1: is if it happened to my daughter, how would I
Speaker 1: feel about it? Or mysef if it happened to my children.
Speaker 1: If you told me, hey, your kids each have a
Speaker 1: hookworm in their gut, I'd be like, all right, that's fine.
Speaker 2: Oh.
Speaker 1: I wouldn't be like you need to put in anti helmethics.
Speaker 1: Anti helmethics being the drugs that you use to kill
Speaker 1: these parasites. But if somebody was like, your kids have
Speaker 1: two hundred hookworms in their guts, I'd be like, all right,
Speaker 1: right now, we got to do something about it.
Speaker 2: Well, where's the line there? Between one and two hundred
Speaker 2: fifty hookworms? Is okay? Five is okay?
Speaker 1: So first of all, the way that you figure out
Speaker 1: how many they have, you can't like call up and
Speaker 1: be like, hey, gut, how many hookworms are in there?
Speaker 1: And what you usually do is you look to see
Speaker 1: how many eggs are in one gram of feces and
Speaker 1: that's how you do the county at the roundworms literally
Speaker 1: make two hundred thousand eggs a day. Just incredible numbers
Speaker 1: of eggs a day. Both hookworm and whipworm can make
Speaker 1: up to like ten thousand eggs a day. So I
Speaker 1: would trust a doctor. If a doctor said, like, your
Speaker 1: kids are almost certainly not going to get infected by
Speaker 1: any more of these because you've confirmed that, like you know,
Speaker 1: the latrine that was broken in your community has been
Speaker 1: fixed and they have very light infections, I'd be like, well,
Speaker 1: maybe that's fine. But if they were like there's blood
Speaker 1: in your kid's stool. You've got so many hookworms that
Speaker 1: they're like losing blood, then yeah, we should do something
Speaker 1: about it.
Speaker 2: And you think there are cultural differences around the world,
Speaker 2: like in some countries they're like, no big deal hookworms.
Speaker 2: In other countries they're like, you must kill every worm
Speaker 2: inside the body. Or do you think medical practices are
Speaker 2: pretty constant around the world.
Speaker 1: I don't know, But what I can say is that
Speaker 1: the World Health Organization, their goal isn't to get rid
Speaker 1: of the parasite entirely. They're focused particularly on trying to
Speaker 1: make sure that people with heavy infections they get treated.
Speaker 1: I mean, they would love for the parasite to be
Speaker 1: eradicated entirely. And we're going to get to this, but
Speaker 1: part of the difficulty there is that you have to
Speaker 1: completely upgrade the sanitation system to get rid of these
Speaker 1: parasites more or less entirely. But having low intensity infections,
Speaker 1: so just a couple of worms is not a problem.
Speaker 1: And again maybe there's some evidence that it reduces inflammation.
Speaker 1: But if you have a lot of askris, they're like
Speaker 1: pretty big parasites, and so sometimes they end up in
Speaker 1: like the same part of your gut and they literally
Speaker 1: cause it compaction and nothing else can get through, and
Speaker 1: so in that case you have to get a surgery
Speaker 1: to get them removed.
Speaker 2: Wow.
Speaker 1: Sometimes the photos of these things end up in your
Speaker 1: parasitology textbooks and I'm like, that's the ick that I
Speaker 1: didn't need to see. But it's important. Hookworm causes a lot.
Speaker 2: Of blood loss because they're drinking your blood.
Speaker 1: Because they're drinking your blood, and then they also leave
Speaker 1: gaping wounds when they move to another spot and you
Speaker 1: keep bleeding.
Speaker 2: That's not very considerate. You know, there are a lot
Speaker 2: of animals that sip our blood. But mosquitos at the
Speaker 2: very least don't leave you like dripping blood.
Speaker 1: Mm hmm. They're totally jerks. I agree whipworm. If you
Speaker 1: have really high infections, they get kind of pushed to
Speaker 1: areas that they'd rather not be, which is like farther
Speaker 1: down in the bowel, and they cause troubles with some
Speaker 1: kids who end up just constantly feeling like they need
Speaker 1: to have a bowel movement because they've got all these
Speaker 1: parasites in there. And sometimes that causes prolapsed anus, which
Speaker 1: is really I just can't imagine if one of that
Speaker 1: happened to one of my kids. It would be so upsetting.
Speaker 1: So then you need a surgery again to kind of
Speaker 1: like put everything back in. But another problem that's less
Speaker 1: gross to talk about is if you have a lot
Speaker 1: of these parasites, there's concerns that they cause declines in
Speaker 1: physical growth and cognitive development. And partly that's because you're
Speaker 1: just you don't have the energy. The parasites are sucking
Speaker 1: your blood. Some of them like maybe take particular vitamins out.
Speaker 1: So a big reason that we want to treat for
Speaker 1: these parasites is because having heavy infections when you're young
Speaker 1: can have implications for the rest of your life. And
Speaker 1: kids tend to get these infections more than adults, which
Speaker 1: is surprising. It's amazing to me that we ever teach
Speaker 1: kids to wash their hands regularly, because it's so hard
Speaker 1: to get kids to wash their hands. But that's why
Speaker 1: a lot of kids get infected.
Speaker 2: Well, I just heard from Katrina Real Time Consulting that
Speaker 2: there are some things that infect us in the US,
Speaker 2: and in the US, if they find it in you,
Speaker 2: they will prescribe medicines to try to remove it, whereas
Speaker 2: in other countries, like in Ecuador, they're like, yeah, no
Speaker 2: big deal. So, for example, blastocystis some you carry it
Speaker 2: which infects the body, and in some countries they're like, yeah,
Speaker 2: no big deal. But in the US we're like, yeah,
Speaker 2: I gotta get rid of it. And it's not clear
Speaker 2: whether it like does more harm than good. It's like
Speaker 2: on this fuzzy edge.
Speaker 1: Oh interesting, did you just answer an email. I'm so
Speaker 1: glad we have Katrina as a consultant for the show.
Speaker 1: So we know that these parasites at high intensities are bad,
Speaker 1: and so you don't want your kids infected with them,
Speaker 1: and so should we talk a little bit about the
Speaker 1: history of trying to do battle with these worms. Yeah,
Speaker 1: as you remember from the intro, around nineteen hundred is
Speaker 1: when that German parasitologist was self infecting himself and the
Speaker 1: patient at the hospital and figuring out the life cycle
Speaker 1: for hookworm. About ten years after that, John D. Rockefeller,
Speaker 1: this you know, super rich guy with all of the
Speaker 1: oil money. He decides that he wants his foundation to
Speaker 1: try to eradicate hookworm from the American South. So this
Speaker 1: was a big problem in the American South because it's warm,
Speaker 1: it's moist, these are great conditions for the eggs to
Speaker 1: last for a really long time in the environment. So
Speaker 1: he creates the Rocket Feller Sanitary Commission. And even though
Speaker 1: they said they were going to eradicate hookworm, their goal
Speaker 1: right from the beginning was to just control it and
Speaker 1: make it a little bit less bad. But part of
Speaker 1: how they advertised why this was important was they were
Speaker 1: essentially blaming hookworm for this myth of Southern laziness. So
Speaker 1: the parasite like makes you lethargic, it makes you sort
Speaker 1: of not want to move, not want to eat, like
Speaker 1: you just feel miserable. If you've got a bunch of
Speaker 1: worms in your gut, and so they referred to hookworm
Speaker 1: as the germ of laziness. And so through this system
Speaker 1: of like education and treat and they tried to get
Speaker 1: a handle on it. So they made a bunch of
Speaker 1: videos about the hookworm life cycle, and I spent way
Speaker 1: too many hours watching these videos the other day. And
Speaker 1: then they had some treatments at the time, but the
Speaker 1: treatments were like also a little bit toxic, and so
Speaker 1: there were some people who died when they took the treatment,
Speaker 1: which is clearly less than ideal. Yeah, but the plan
Speaker 1: at the time was to get people to go to
Speaker 1: like doctors get their stool checked to see if they
Speaker 1: had eggs, and if so, you'd get a treatment followed
Speaker 1: with drinking a bunch of like epsom salts and water,
Speaker 1: which would sort of clear out your bowels, let's say,
Speaker 1: and the parasites would sort of pass out and you'd
Speaker 1: see them pretty gross. But the problem is that without
Speaker 1: actually upgrading the sanitation system, people just kept getting infected again.
Speaker 1: And so there were some studies that tried to find
Speaker 1: an effect of this sanitary commission, and the results are
Speaker 1: kind of mixed. When some people analyzed the data, they'd say, like,
Speaker 1: you know, people were getting more time in school because
Speaker 1: like sometimes you feel so I mean, you don't go
Speaker 1: to school, And so they were like, you know, saying
Speaker 1: the prevalence was lower. But then there's other studies that
Speaker 1: looked at improvements in the South over time and found
Speaker 1: things like how many days you went to school each
Speaker 1: year had been improving over time already, and so maybe
Speaker 1: it had nothing to do with huckworm eradication. It could
Speaker 1: have just been that the South was getting better at
Speaker 1: sanitation over time and this commission did nothing beneficial.
Speaker 2: And do you know the scientific context, like this is
Speaker 2: a whim of a zillionaire essentially deciding we're going to
Speaker 2: do this medical program. Is that what the medical establishment
Speaker 2: or the scientific community would have wanted anyway, Like if
Speaker 2: they've just given them the money, is it sort of
Speaker 2: like best practices or was it just sort of like
Speaker 2: off in the weeds.
Speaker 1: Yes, we are essentially having some of the same debates today.
Speaker 1: So it was like a reasonable first effort, and that
Speaker 1: the debates are, you know, is it worth trading without
Speaker 1: improving sanitation? Like what kind of improvements can you make
Speaker 1: if you're not actually solving the root problem, which is
Speaker 1: that you need to tackle these sanitation problems and so
Speaker 1: so there are a bunch of organizations that were sort
Speaker 1: of inspired by these early Rockefeller efforts, and a parasitologist
Speaker 1: named u Styles was one of the first ones who
Speaker 1: was like really beating the drum for we need to
Speaker 1: tackle hookworm in the South, and he ended up working
Speaker 1: with them on a bunch of this stuff. Yes, I
Speaker 1: think that there were probably engaging in practices that were
Speaker 1: fairly scientifically sound at the time, but there is some
Speaker 1: debate about whether or not they were balancing the risks
Speaker 1: of the medication against the benefits well enough for the
Speaker 1: people who died, and they ended up extending their reach
Speaker 1: into some other countries. And there's also debates about the
Speaker 1: relative impacts of like what their medication did in terms
Speaker 1: of killing people versus helping people. So it's not all rosy,
Speaker 1: which is perhaps exactly what you'd expect about this time
Speaker 1: in American history. Let's take a break now, So at
Speaker 1: this point we understand the life cycle of these parasites.
Speaker 1: There have been some efforts to try to eradicate these parasites,
Speaker 1: but they've been met with sort of limited success. Where
Speaker 1: are we now? What have we tried in the one
Speaker 1: hundred plus year since the Rockefeller Sanitary Commission. You'll get
Speaker 1: your answer after the break.
Speaker 2: All right, we are back and we are battling the
Speaker 2: ick today on the podcast we are learning all about
Speaker 2: the worms in you, the worms in me, the worms
Speaker 2: that are in all of us and make us who
Speaker 2: we are. So tell us, Kelly, how far have we
Speaker 2: come in battling these worms or have we just given
Speaker 2: up and accepted that it's a wormy world?
Speaker 1: We will not give up. The Rockefeller Sanitary Commission, you know,
Speaker 1: met with mixed success, but eventually they ended up backing
Speaker 1: out because they were like, look, we can't improve sanitation.
Speaker 1: If you can't improve sanitation, you really can't solve the
Speaker 1: root problem. But around the nineteen fifties nineteen sixties, sanitation
Speaker 1: in the South improved on its own, and the percent
Speaker 1: of the population that's infected by this parasite went way down,
Speaker 1: and as medical care got better and various parts of
Speaker 1: the country got lifted out of poverty, things got way better.
Speaker 1: We do still have the parasite though in some areas
Speaker 1: of like rural Alabama, where sanitation has broken down and
Speaker 1: people are getting infected by these parasites again, but in general,
Speaker 1: in most parts of the United States, just simply the
Speaker 1: act of like going through development and improving sanitation eventually
Speaker 1: saved a bunch of people from these parasites.
Speaker 2: And do we get flare ups when there's a natural disaster,
Speaker 2: you know, floods and hurricanes and stuff that interfere with sanitation.
Speaker 1: I think in the United States that's pretty rare. But
Speaker 1: around the world I can imagine that those kinds of
Speaker 1: problems would make this stuff much worse. But this has
Speaker 1: remained a serious problem in Asia and Africa. In Asia,
Speaker 1: night soil sort of makes it difficult, but in Africa
Speaker 1: you have, you know, sanitation issues, and so the World
Speaker 1: Health Organization has become interested in trying to reduce the
Speaker 1: prevalence of this parasite, like the percent of the population
Speaker 1: that's infected. But you know, even more importantly, you want
Speaker 1: to reduce the incidents of people who have lots of
Speaker 1: these parasites, because those are the people who are the
Speaker 1: most likely to like, really experience some problems. In the
Speaker 1: nineteen seventies, some drugs that were developed for livestock turned
Speaker 1: out they could be used for parasites to treat these infections,
Speaker 1: and that's albendazol and me bendazol. They're way less toxic
Speaker 1: than prior medications, and so like that's good news. But
Speaker 1: for a while, we like had those medications, but we
Speaker 1: weren't really doing anything with them. But then in the
Speaker 1: twenty tens, the ball really got rolling. The World Health
Speaker 1: Organization started up a program and amazingly, so, like I
Speaker 1: usually love to hate pharmaceutical companies because medications are so expensive,
Speaker 1: but they've donated like literally billions of doses of these
Speaker 1: medications to help the World Health Organization do battle with
Speaker 1: these dirt worms.
Speaker 2: Just out of the goodness of their pharmaceutical hearts.
Speaker 1: I mean, I'm sure it was a pr move too.
Speaker 1: So one of the problems with treating people in areas
Speaker 1: where there's not a lot of money is that, you know,
Speaker 1: pharmaceutical companies can't really make a profit by giving them medications,
Speaker 1: and so surprisingly often there are pharmaceutical companies who are
Speaker 1: willing to donate in cases like this, and so here
Speaker 1: you get these huge donations. Maybe I'm being two nice.
Speaker 1: I don't know if it happens often, but in this
Speaker 1: case it happened. So now you've got all of these
Speaker 1: doses of drugs and you've got to try to figure
Speaker 1: out what to do. And it turns out that, you know,
Speaker 1: the Rockefeller Sanitary Commission, they would test people before giving
Speaker 1: them medications, which involved like taking a sample of feces,
Speaker 1: putting it under a microscope looking for the signs of
Speaker 1: the eggs. But that takes a long time, and time
Speaker 1: is money because you need to hire people to do that,
Speaker 1: you need to get the microscopes in, and so it
Speaker 1: was decided that actually it would be prohibitively expensive to
Speaker 1: treat based on already having an infection. So instead, what
Speaker 1: they decided to do was bring these drugs into countries
Speaker 1: that had a pretty high percent of the population that
Speaker 1: was carrying the worm, and then they would go to schools,
Speaker 1: and because kids usually have the heaviest infections, they would
Speaker 1: dole out the medication at the school. So there'd be
Speaker 1: a day where like the teacher would pass these pills
Speaker 1: out to the students and they would take the medication,
Speaker 1: and in that way they were trying to treat the
Speaker 1: entire population. I think there was also some efforts to
Speaker 1: give it to moms when they would come in for
Speaker 1: like maternal care checks, so if they were pregnant or lactating,
Speaker 1: because both of these are stages where you need your
Speaker 1: energy and if you don't have it, it could cause
Speaker 1: long term impacts.
Speaker 2: And was there any resistance to this? You know, there's
Speaker 2: like classic resistance to vaccination in some portions of society,
Speaker 2: where people against this somehow, or everybody happily accepting these drugs.
Speaker 1: It can't be the case that everyone happily accepted the drug.
Speaker 1: That's a great question. I didn't come across stories like
Speaker 1: that when I was doing the research for this episode.
Speaker 1: Doctor Henderson wrote a great book about the eradication of smallpox.
Speaker 1: He was in charge of the World Health Organization's effort
Speaker 1: to eradicate smallpox, if I remember correctly, And there was
Speaker 1: a lot of that, a lot of like people who
Speaker 1: didn't want to get the vaccine, and so then there
Speaker 1: was a lot of engaging with community members to convince
Speaker 1: the community members that this would be better for the
Speaker 1: community overall. And so a lot of like trust that
Speaker 1: needed to be built between medical practitioners and the communities
Speaker 1: that they were working with. And again that totally makes sense, right.
Speaker 1: The Rockefeller Sanitary Commission that we were talking about. Some
Speaker 1: kids died from the medications, and so like asking questions
Speaker 1: was reasonable. But I think in general this program is
Speaker 1: thought to have been pretty successful in terms of like
Speaker 1: getting medications into kiddos that probably needed it.
Speaker 2: And is it analogous to vaccines where it's helpful to
Speaker 2: the whole population for an individual to take it, because
Speaker 2: then you're just reducing the number of worms that are
Speaker 2: like in the whole ecosystem the same way that like
Speaker 2: taking a vaccine reduces the prevalence of the disease, so
Speaker 2: that folks who for whom the vaccine doesn't work, you're
Speaker 2: also protecting them.
Speaker 1: Yeah, so that was a big part of the hope
Speaker 1: was that you know, by targeting the people who have
Speaker 1: the most parasites, those would also be the people who
Speaker 1: would be producing the most eggs and putting those eggs
Speaker 1: back into the environment. So by reducing their wormburden, you
Speaker 1: should read reduce the risk for everybody else. But a
Speaker 1: problem is that it's really expensive and difficult to do
Speaker 1: the follow up monitoring to make sure that that kind
Speaker 1: of stuff is happening, and so often these drugs will
Speaker 1: get passed out, but then the subsequent monitoring won't happen.
Speaker 1: And the studies that have been done to look for
Speaker 1: like do you get improvements in growth and you know,
Speaker 1: cognitive abilities in communities where you give out these medications.
Speaker 1: You know, again often that's not done. Are those assays,
Speaker 1: those tests that data collection is not happening, And then
Speaker 1: in the areas where it is happening, some studies find
Speaker 1: in effect and others don't. And that's not too surprising
Speaker 1: because you know, as we've said, having a few worms
Speaker 1: is not a big deal, but having a lot of
Speaker 1: worms is. So you might expect that the people who
Speaker 1: are getting the benefit would be the small subset of
Speaker 1: the population who had a heavy worm burden that got
Speaker 1: significantly knocked down by this medication. So if you're looking
Speaker 1: at a whole population, it might be hard to target
Speaker 1: and see those improvements.
Speaker 2: Well, it's always fascinating and difficult to balance the individual
Speaker 2: choices with the public health recommendations, right, And the folks
Speaker 2: who work on this have such a difficult job. I
Speaker 2: really have a lot of respect for that.
Speaker 1: Oh my gosh, yeah, no me also and their job,
Speaker 1: like it's difficult because so you go out there once
Speaker 1: and first of all these medications don't always kill all
Speaker 1: the parasites. I was reading a review paper that said
Speaker 1: that often like it knocks down ninety percent of the parasites,
Speaker 1: but some of the parasites still live, and so you
Speaker 1: need to keep going out there and giving the medication
Speaker 1: to people over and over again. So it kills some
Speaker 1: of the worms that they have, but it doesn't at
Speaker 1: all stop them from getting infected by worms again in
Speaker 1: the future. Oh yeah, So are you going to go
Speaker 1: out there every year for the rest of eternity and
Speaker 1: give medication to these communities. That doesn't seem like a
Speaker 1: feasible long term solution. So these programs are often also
Speaker 1: pushing like better sanitation and other ways to kind of
Speaker 1: try to break the cycle of these diseases, and there
Speaker 1: has been pretty good success, Like, for example, Kenya was
Speaker 1: really serious about giving out the medications and doing monitoring
Speaker 1: and they're thought to have had a lot of success
Speaker 1: with the program. Hand in South Korea also gave out
Speaker 1: the drugs at school, but they also screened everybody, provided
Speaker 1: education about how you get the parasites. They started treating
Speaker 1: their night soil, so treating the human and livestock waste
Speaker 1: before it got put on plants so the parasites would
Speaker 1: be killed first. That even started like putting legislation into
Speaker 1: place to try to make some of these like improvements permanent.
Speaker 1: And they've been really successful at controlling the parasites. Okay,
Speaker 1: so what do we do next? So there's some areas
Speaker 1: where it's mostly been controlled, but there's other areas where
Speaker 1: I think you're just not really going to be able
Speaker 1: to control the problem until we have better sanitation. And
Speaker 1: so as countries develop and their sanitation systems improve, probably
Speaker 1: a lot of these problems will go away, sort of
Speaker 1: like we saw in the American South. There's also some
Speaker 1: effort to work on vaccines for some of these parasites.
Speaker 1: We're going to do a whole episode on why vaccine
Speaker 1: development and parasites is difficult, And I'm not going to
Speaker 1: get into it much now because frankly, I don't know
Speaker 1: the answer and I'll need to research that. But there
Speaker 1: are some vaccines that are being trialed right now, and
Speaker 1: even if those vaccines aren't completely successful, some combination of
Speaker 1: vaccines plus medication might like put a break in transmission
Speaker 1: and allow communities to sort of eradicate the parasite. We hope.
Speaker 2: How do vaccines work for a worm? I mean, I
Speaker 2: get the general picture for like a microbe, but does
Speaker 2: your immune system learn to combat these particular worms or what?
Speaker 1: Yeah, that's the hope. But so one of the difficulties
Speaker 1: is that humans, when you get a hookworm infection and
Speaker 1: then you clear the infection, if our immune system remembered it,
Speaker 1: you'd expect us to be, you know, kind of immune
Speaker 1: to the parasite the next time around. But our immune systems,
Speaker 1: for whatever reason, don't seem to remember it, and so
Speaker 1: we don't have a memory in our immune system for
Speaker 1: something like hookworms the same way we do for like
Speaker 1: the flu virus or the bacteria that cause a cold.
Speaker 1: I don't totally understand why that's the case, but it
Speaker 1: probably complicates the creation of a vaccine. But if you
Speaker 1: could get your immune system to remember, maybe by regularly
Speaker 1: giving people vaccines, like very regular reminders, and you couple
Speaker 1: that with medication to killed a few parasites, you do
Speaker 1: get maybe that's a viable solution going forward. But I
Speaker 1: think in general, sanitation is just like having a public
Speaker 1: sanitation system. That's sort of like getting a handle on
Speaker 1: all of this is the clearest way. There's some other proposals,
Speaker 1: like there's a containment system called biogas, and you put
Speaker 1: your livestock waste and your human waste into this container
Speaker 1: and it releases like methane and some other gases that
Speaker 1: can then be piped into the house for like cooking
Speaker 1: and heating, like propane. And I wrote somebody who works
Speaker 1: on this and said, does it smell like human feces,
Speaker 1: because I wouldn't want that piped into my house, and
Speaker 1: he said, no, it doesn't stink. It's methane. And then additionally,
Speaker 1: you get this anaerobic environment inside of the thing with
Speaker 1: all of the waste anaerobic meaning meaning no oxygen, and
Speaker 1: that kills the parasites and so then you can subsequently
Speaker 1: use that human waste as night soil and it's safe.
Speaker 2: But there's something beautiful about cooking your food with farts.
Speaker 1: Basically, yeah, I mean, you know, if I lived in
Speaker 1: an area where I couldn't afford heat and you could
Speaker 1: heat up farts to keep warm and it didn't stay,
Speaker 1: I would do it because I like being warm anyway.
Speaker 1: So there's a number of different proposals for how to
Speaker 1: do it, you know, keeping people from encountering these parasites
Speaker 1: in the first place is a clear way to do it.
Speaker 1: But it's just hard to get sanitation systems running in
Speaker 1: a bunch of different places. So what is the big
Speaker 1: take home here? The big take home is that once
Speaker 1: we understood how these life cycles worked, that did give
Speaker 1: us a clear path forward for tackling these infections. But
Speaker 1: it's not actually always easy to implement the strategies that
Speaker 1: you know would kill these parasites because there's just lots
Speaker 1: of stuff going on and life is complicated. So this
Speaker 1: is another parasite that is still with us and infecting
Speaker 1: about twenty five percent of our population. But hopefully one
Speaker 1: day we'll be able to get a handle on it.
Speaker 1: We've had some success so far. Hopefully we'll be able
Speaker 1: to reduce human suffering in the near future.
Speaker 2: Well, so, my last question for you is we've come
Speaker 2: a lot long way in understanding what's going on inside
Speaker 2: the body and discovering these critters living inside of us.
Speaker 2: Do you think there are still big discoveries left to
Speaker 2: be made in terms of like what's living inside humans
Speaker 2: or we mostly understand it because we've like sequenced our
Speaker 2: poop and sequenced our saliva, and we know sort of
Speaker 2: what critters are in there.
Speaker 1: I've been going through old issues of the Journal of Parasitology.
Speaker 1: I'm going to answer your question eventually, I promise. And
Speaker 1: they used to have at the end of each issue
Speaker 1: a list of the new parasites of humans that had
Speaker 1: been identified, and there were a lot. There used to
Speaker 1: be a lot on those pages, but at some point
Speaker 1: they dropped that offering entirely, like new issues don't have that,
Speaker 1: and I don't know if that's because it's just not
Speaker 1: worth keeping a list anymore because you can just find
Speaker 1: lists online so easily. We do still find parasites occasionally
Speaker 1: infecting people. Usually they're sort of rare infections, but you know,
Speaker 1: we get a lot of zonotic infections, so which means
Speaker 1: they are parasites and pathogens that jump from wild populations
Speaker 1: to human populations as we sort of encroach upon the
Speaker 1: habitats of wild animals. So it wouldn't surprise me if
Speaker 1: more parasites and pathogens will be jumping into people the
Speaker 1: more we encroach into the habitats of wild animals. I'm
Speaker 1: sure there's more that we'll have to learn.
Speaker 2: And when aliens come, maybe some of their parasites will
Speaker 2: take up home in our bodies. You know, I had
Speaker 2: to bring it back to aliens eventually.
Speaker 1: We can hope. Oh wait, yeah, how do we We
Speaker 1: haven't touched on cannibalism yet today, but anyway, missed opportunities.
Speaker 1: But yes, the alien parasites. I would love to study
Speaker 1: some alien parasit.
Speaker 2: Well, I'm just so amazed at how much we still
Speaker 2: have left to learn about the workings of our own
Speaker 2: body and the balances between these things, and how much
Speaker 2: these things are helping and hurting and our ancient history
Speaker 2: with these crazy ichy worms.
Speaker 1: Yeah, but crazy, icky, fascinating words. Yes, they're very interesting.
Speaker 1: But yes, I would like to see no humans suffering
Speaker 1: from heavy infections ever.
Speaker 2: Again. Well, I hope it hasn't been too much suffering
Speaker 2: for you to hear about this crazy biological mystery and
Speaker 2: you haven't had too much I while you're driving work
Speaker 2: or eating your lunch, we appreciate you coming along for
Speaker 2: the ride.
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