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How did we tackle Trichinella? · Daniel and Kelly’s Extraordinary Universe

0:06
Speaker 1: In nineteen forty seven, doctor Norman Stole gave his presidential
0:09
Speaker 1: address to the American Society of Parasitologists. His talk was
0:13
Speaker 1: called This Wormy World, And if you study parasites, this
0:17
Speaker 1: talk is a real classic. Stole wanted an estimate for
0:21
Speaker 1: how many people in the world were carrying particular kinds
0:24
Speaker 1: of wormy parasites. So we're talking things like nematodes, tapeworms,
0:28
Speaker 1: and trematodes, not the kind of things that cause the flu,
0:31
Speaker 1: so not bacteria or viruses. So the context here is
0:35
Speaker 1: that World War II had recently ended, but the problems
0:38
Speaker 1: for US soldiers who participated in the war had not.
0:42
Speaker 1: Soldiers returning home from the war had brought back with
0:45
Speaker 1: them the parasitic diseases that are found all over the world.
0:49
Speaker 1: US interest in parasites skyrocketed as Americans were suddenly forced
0:53
Speaker 1: to observe how horrible some of these parasitic diseases can be. So,
0:57
Speaker 1: how many wormy infections are out there? Well, Stoll starts
1:01
Speaker 1: by noting how bad the data for an analysis like
1:04
Speaker 1: this are. There's just not great surveys that are comprehensive.
1:08
Speaker 1: But he set out to do his best. What he
1:10
Speaker 1: concludes is that there were two point two billion wormy
1:15
Speaker 1: infections and a population of just under two point two
1:19
Speaker 1: billion people at the time, so this isn't counting the
1:22
Speaker 1: number of parasites in people. One infection would be like, okay,
1:26
Speaker 1: you have one of a particular kind of nematode in someone,
1:30
Speaker 1: But these infections were not evenly distributed. On average, one
1:34
Speaker 1: out of every three Americans or Europeans were infected, but
1:38
Speaker 1: in the USSR that number was up to two out
1:41
Speaker 1: of three people. For every three people in Asia, the
1:44
Speaker 1: Middle East, and South America there were four infections, so
1:47
Speaker 1: that means out of three people, one of those people
1:50
Speaker 1: is probably harboring two different wormy parasite species, and every
1:54
Speaker 1: person in Africa on average was estimated to harbor two
1:58
Speaker 1: helminth parasite species. But Stole notes a bit of optimism
2:03
Speaker 1: and points out that six out of the seven cases
2:06
Speaker 1: of wormy infections could have been stopped with proper sanitation,
2:10
Speaker 1: so there's some ability to do something about this. So
2:13
Speaker 1: how far have we come since nineteen forty seven. Well,
2:17
Speaker 1: in some areas we've made great progress. For example, Stole
2:21
Speaker 1: mentioned that a nematode called Trichinellus brellus was known as
2:25
Speaker 1: the most serious parasitic disease in New England. At the time,
2:29
Speaker 1: one in six Americans were infected with this parasite. Now,
2:33
Speaker 1: triconilosis is a rare disease in the United States, with
2:36
Speaker 1: only about fifteen confirmed cases in the entire country per year.
2:41
Speaker 1: And today we're going to be talking about this public
2:44
Speaker 1: health success story, but in future episodes, we're also going
2:48
Speaker 1: to talk about some parasites that still plague humans worldwide,
2:51
Speaker 1: including here in the United States. For example, according to
2:54
Speaker 1: the World Health Organization, one and a half billion people
2:58
Speaker 1: are infected with nematode parasite that are picked up from
3:01
Speaker 1: the soil. All right, so let's dig in. Welcome to
3:04
Speaker 1: Daniel and Kelly's extraordinarily wormy Universe.
3:21
Speaker 2: Hi.
3:21
Speaker 3: I'm Daniel, I'm a particle physicist, and I've never been
3:24
Speaker 3: infected by a parasite to my knowledge.
3:28
Speaker 1: I'm Kelly Wiener Smith, and I bet Daniel has been
3:30
Speaker 1: infected at some point. And if I had to guess,
3:33
Speaker 1: there'd be a good chance that you would have gotten
3:36
Speaker 1: pinworms from your kids when they were young.
3:38
Speaker 3: Ooh, pinworms are those the ones I'm thinking about that
3:40
Speaker 3: make you itching a very uncomfortable place.
3:42
Speaker 1: That's right. I think Actually at some point we should
3:45
Speaker 1: have a whole episode on pinworms, cause why not. But
3:48
Speaker 1: oh nope, maybe not. Daniel is going to be a
3:51
Speaker 1: long couple of years working with me if pinworms give
3:54
Speaker 1: you the eb gbs.
3:57
Speaker 3: It's just that particular itch just really gets me, if
4:00
Speaker 3: you know what I mean.
4:01
Speaker 1: No, No, I get it, I get it. Actually, the
4:03
Speaker 1: mom nematode sneaks out at night and deposits eggs with
4:07
Speaker 1: like a sticky substance in the spot that you're thinking of,
4:10
Speaker 1: because scratching is how the parasite transmits, how it gets
4:13
Speaker 1: under fingernails and then ends up in the environment and
4:15
Speaker 1: then ends up getting eaten, so that it is very
4:18
Speaker 1: purposefully caused by the parasites.
4:20
Speaker 3: I know, And I use that story as a way
4:23
Speaker 3: to dissuade my kids from biting their fingernails. Oh good,
4:26
Speaker 3: because I'm like, you know what you're doing, you know
4:28
Speaker 3: where you're gonna get itchy if you keep doing that
4:30
Speaker 3: and it works, it works.
4:32
Speaker 1: No, I bet yeah. People feel real gross when you
4:34
Speaker 1: tell them about parasites. It's a good way to dissuade people.
4:37
Speaker 1: From certain bad behaviors, no doubt.
4:39
Speaker 3: All right, So, since we're being personal, what is the
4:42
Speaker 3: grossest parasite you've been infected by?
4:44
Speaker 1: Oh, gosh, that I've been infected by. Well, I guess
4:47
Speaker 1: if my parasite we're including viruses and bacteria, I guess
4:51
Speaker 1: anything that makes me puke. But I haven't been infected
4:53
Speaker 1: by anything that gross. But now, I had an antibiotic
4:58
Speaker 1: resistant wound near my ankle once and that was gross
5:01
Speaker 1: because I just wouldn't go away, and that was kind
5:03
Speaker 1: of scary, and I was super stressed, which I think
5:05
Speaker 1: was like suppressing my immune system too, and so it
5:07
Speaker 1: was bad news.
5:09
Speaker 3: What about you, Well, to me, being infected by a
5:12
Speaker 3: little microbe, isn't that gross? It's like, yeah, that's invisible.
5:15
Speaker 3: The bigger it is, the weirder it is, the more
5:18
Speaker 3: gross it is. Like being infected by something that's like
5:21
Speaker 3: actually a worm size to me is creepy. It's like
5:23
Speaker 3: crawling around inside you. And so like, imagine being infected
5:27
Speaker 3: by something larger, you know, baseball sized or like football size,
5:30
Speaker 3: that would be like, oh, that's nightmare fuel for me.
5:33
Speaker 3: But yeah, I don't know that I've ever had a
5:35
Speaker 3: worm inside me. But apparently Kelly things that I have,
5:38
Speaker 3: So maybe I am a wormy.
5:39
Speaker 1: I don't actually know that you have me. I'm sure
5:41
Speaker 1: your hygiene is impeccable and that is probably kept you safe.
5:45
Speaker 1: But now there's some pretty nasty like as grade worms,
5:47
Speaker 1: which maybe we'll talk about at some point. They are
5:49
Speaker 1: really big, and when you see surgeries where people are
5:53
Speaker 1: like trying to remove many of them from someone's that
5:57
Speaker 1: even grosses me out. I can't eat pasta for days exactly.
6:02
Speaker 3: Well, I appreciate you giving me the benefit of doubt.
6:04
Speaker 3: Although physicists are not exactly famous for their hygiene. You know,
6:07
Speaker 3: that's not like top ten ways you become a physicist
6:11
Speaker 3: or things we're famous for. But you know, I appreciate it.
6:14
Speaker 3: I do try to keep clean. Thank you very much.
6:16
Speaker 1: You're welcome. I was thinking about you as a human
6:18
Speaker 1: being and not really a physicist in particular.
6:21
Speaker 4: You know.
6:23
Speaker 3: That doesn't work in my favor. Yeah, all right, but
6:27
Speaker 3: today we are not talking about Daniel's hygiene. We're talking
6:30
Speaker 3: about humans more generally.
6:32
Speaker 1: Yeah, and we're talking about them because we got a
6:34
Speaker 1: great question from a listener named Patrick, And let's go
6:37
Speaker 1: ahead and listen to that question.
6:38
Speaker 3: Now, how many parasites are living in all of us,
6:42
Speaker 3: how common are the bad ones? And where do we
6:46
Speaker 3: pick them up? Oh? Man, it sounds to me like
6:48
Speaker 3: Patrick is looking for nightmares.
6:50
Speaker 1: Oh it sounds to me like Patrick is giving me
6:52
Speaker 1: my Christmas present early by allowing me to talk about parasites.
6:56
Speaker 1: And so, you know, at the intro, I talked about
6:59
Speaker 1: how in nineteen forty seven there was this estimate that
7:02
Speaker 1: there's two point two billion parasitic infections and a population
7:05
Speaker 1: of under two point two billion people. So some people
7:08
Speaker 1: are infected by more than one parasite. And I wasn't
7:11
Speaker 1: actually able to find a comparable estimate for now, And
7:15
Speaker 1: I think partly that's because the way he grouped parasites
7:18
Speaker 1: together is not really a biologically relevant category that people
7:22
Speaker 1: care about anymore, and so I wasn't able to find
7:25
Speaker 1: a comparable number. But I am going to go through
7:28
Speaker 1: some of the main parasitic infections that have plagued humans
7:31
Speaker 1: in our recent past, but we managed to get rid of,
7:34
Speaker 1: and then some that are still a problem today in
7:36
Speaker 1: the United States and in other parts of the world.
7:39
Speaker 1: But I figured today we would start with a success story.
7:43
Speaker 3: That's good because I was afraid that the message of
7:45
Speaker 3: this episode was going to be like, there's parasites everywhere,
7:48
Speaker 3: all up in your eyeballs and in your earballs and
7:51
Speaker 3: in your noseballs and everything.
7:53
Speaker 1: Well, you know, especially if you live in the United
7:58
Speaker 1: States and you're lucky enough to be in an area
8:00
Speaker 1: where there's really good sanitation, you probably are pretty safe.
8:04
Speaker 1: But you know that's not necessarily true in other parts
8:06
Speaker 1: of the world. We're very lucky here.
8:08
Speaker 3: All right, Well, let's dive in, because I want to
8:10
Speaker 3: know by the end of this episode how likely am
8:12
Speaker 3: I to have worms living inside me? Right now?
8:15
Speaker 1: Well, we're only talking about one worm. And I was
8:18
Speaker 1: interested in figuring out what people know about this worm,
8:21
Speaker 1: because at least in the United States, infections are very
8:24
Speaker 1: uncommon these days, About fifteen cases of infection with this
8:27
Speaker 1: parasite are recorded per year for a disease that once
8:31
Speaker 1: infected one out of six Americans. So we've made a
8:33
Speaker 1: lot of progress, and so I was wondering have people
8:36
Speaker 1: heard about this before? So I asked our audience, what
8:39
Speaker 1: is trick andilosis?
8:40
Speaker 3: Right? And if you would like to play on this
8:41
Speaker 3: segment of the podcast in the future, please don't be
8:43
Speaker 3: shy we'd love to have your voice. Write to us
8:46
Speaker 3: to questions at Danielankelly dot org. So before you hear
8:51
Speaker 3: these answers, think to yourself, do you know what trick
8:54
Speaker 3: andilosis is?
8:55
Speaker 1: Also known as trick and osis?
8:57
Speaker 3: Uh no idea the osis at the end.
9:01
Speaker 5: It sounds like it could be some kind of disease
9:04
Speaker 5: or medical conditions.
9:05
Speaker 2: I'm too excited for words. This isn't about cats and
9:09
Speaker 2: uncertainty and quantum mechanics and things I don't understand. This
9:13
Speaker 2: is a worm. It's a parasite. It grows in pork mainly.
9:18
Speaker 2: I grew up in India and it was a real
9:20
Speaker 2: risk that we'd get this, So we had pork that
9:23
Speaker 2: was like leather. You could have put it on your
9:24
Speaker 2: feet and worn it as a shoe.
9:27
Speaker 4: Disease associated with a parasitic infection of a round worm
9:30
Speaker 4: from cysts from muscle from undercooked meat, pork and other
9:35
Speaker 4: animals as well. I believed.
9:41
Speaker 5: By bacteria. Worms go drinkinglysis is an infection drinking alact
9:49
Speaker 5: could be a gear or maybe a braasite. I'm not sure.
9:55
Speaker 5: Trichinosis is a human disease caused by a pair of
10:00
Speaker 5: worm in pork.
10:01
Speaker 6: I think tricknosis is a disease that one can contract
10:04
Speaker 6: from eating undercooked meat. I don't know if it's a parasite.
10:11
Speaker 6: If Kelly's involved, I assume that it must be.
10:13
Speaker 3: Though no idea. Sounds like a bacterium. Trichinosis sounds like
10:19
Speaker 3: the disease that happens to my third chin, and I
10:22
Speaker 3: don't know anything more about it.
10:23
Speaker 4: I have no idea what trickynosis is. However, taking a
10:27
Speaker 4: stub in the dark, I'm going to say parasite, but
10:30
Speaker 4: only because the email asking the question came from Kelly.
10:33
Speaker 4: If the email asking the questions coming Daniel, I would
10:36
Speaker 4: have took a stub in the dock and said a particle.
10:39
Speaker 4: There we go.
10:40
Speaker 3: Tricenosis involves a trial by a tricycle and tragedy.
10:47
Speaker 1: So, Daniel, it is so clear to me that our
10:50
Speaker 1: audience has us totally figured out it is about a
10:53
Speaker 1: parasitic worm.
10:54
Speaker 3: And you know, just because the email doesn't come for
10:56
Speaker 3: me doesn't mean it wasn't particles. I mean, I assume
10:59
Speaker 3: these parasites are made to particles. They're not like fundamental
11:01
Speaker 3: parasites in the universe or anything. These aren't string theory parasites.
11:04
Speaker 1: Are they not posts quantum gravity parasites, nothing like that.
11:08
Speaker 1: These are actual parasites. And I am always so amused
11:13
Speaker 1: by the wonderful answers you all give when you don't
11:15
Speaker 1: know the answer, like probably it's goblins and that was great.
11:20
Speaker 3: All right, So give us the context. Take us back
11:22
Speaker 3: in history. When did we first learn about this particular worm.
11:26
Speaker 1: Well, the first documented case where someone figured out that
11:30
Speaker 1: this worm was causing an infection was from eighteen thirty five,
11:34
Speaker 1: So we're in London at Saint Bartholomew's Hospital. Back then,
11:39
Speaker 1: the way that a bunch of the medical students learned
11:41
Speaker 1: about infections was that an autopsy or a surgery would
11:44
Speaker 1: be happening in the middle of essentially what looks like
11:47
Speaker 1: a theater. Like imagine you're sitting down to watch a play,
11:49
Speaker 1: but instead you're watching an autopsy.
11:51
Speaker 3: The first five rows may be splashed, yes, yeah.
11:55
Speaker 1: And this was back before there was anesthesia, so like
11:57
Speaker 1: amputations were oh through some turns my stomach, that about it.
12:00
Speaker 1: But it was an autopsy and it was a man
12:02
Speaker 1: who had died of tuberculosis. And the surgeons in the
12:05
Speaker 1: middle of the operating theater, they had their scalpels, and
12:07
Speaker 1: they were trying to like get through the body, and
12:10
Speaker 1: the scalpels kept dulling, and they were feeling really frustrated.
12:13
Speaker 1: And when they finally got inside, they got to the
12:16
Speaker 1: diaphragm and one of the surgeons said, I knew it
12:20
Speaker 1: a case of sandy diaphragm.
12:22
Speaker 3: Sandy diaphragm, sandy diaphragm.
12:25
Speaker 1: And so one of the guys who was in the audience,
12:27
Speaker 1: his name was John Paget, He was a medical student,
12:31
Speaker 1: and he said, what causes sandy diaphragm? And this is
12:34
Speaker 1: the thing that was dulling their scalpels. And the surgeons
12:37
Speaker 1: were like, we don't know. Let's go to life.
12:40
Speaker 3: Well, what was the general state of medical knowledge? Like
12:42
Speaker 3: was the inside of the human body a total mystery?
12:45
Speaker 3: And we mostly figured out like the circulatory system and
12:47
Speaker 3: the digestive system and all that. What did we sort
12:50
Speaker 3: of know about the workings of the human body almost
12:52
Speaker 3: two hundred years ago?
12:53
Speaker 1: I think that if you went to a surgeon, it
12:56
Speaker 1: was like a fifty to fifty chance the surgeon made
12:58
Speaker 1: things worse. We'd a medical historian, so maybe the odds
13:02
Speaker 1: were better or worse. I don't really know. We knew
13:05
Speaker 1: a fair bit, you know, Like we knew that if
13:07
Speaker 1: someone had a cancerous growth, you'd try to cut it
13:10
Speaker 1: off real fast. But we didn't have anesthesia, so sometimes
13:12
Speaker 1: you'd get an infection and you'd die from that. It
13:15
Speaker 1: was a dicey time to be someone who needed the
13:18
Speaker 1: help of a professional.
13:20
Speaker 3: And this is before germ theory, right, So we didn't
13:23
Speaker 3: understand there could be microscopic organisms infecting or was this
13:27
Speaker 3: after germ theory.
13:28
Speaker 1: Luayne Hook had been able to see his little animacules,
13:32
Speaker 1: so we knew that there were like tiny little organisms
13:34
Speaker 1: in the world. I don't think we had germ theory,
13:39
Speaker 1: and Lister hadn't figured out ways to establish antiseptic technique.
13:45
Speaker 1: That is all off the top of my head. And
13:48
Speaker 1: maybe we should have like Lindsay Fitzharris, who's this amazing
13:51
Speaker 1: historian of like surgeries and stuff on the show, to
13:55
Speaker 1: give some background there.
13:56
Speaker 3: Because I thought that like middle of this century, we
13:58
Speaker 3: still have folks like going from cadavers to delivering babies
14:03
Speaker 3: and wondering like, hey, why are so many women dying
14:05
Speaker 3: in childbirth? What a mystery? And maybe we should wash
14:08
Speaker 3: our hands.
14:09
Speaker 1: Yeah, No, that is where we were yeah. Okay, we're
14:11
Speaker 1: still before the germ theory. Okay, yeah, yeah, And I
14:14
Speaker 1: think that you know, if they amputated someone's limb, they'd
14:16
Speaker 1: kind of like wipe it off with the napkin maybe,
14:18
Speaker 1: and then amputate the next person's limb. There were lots
14:21
Speaker 1: of microbes being shared between people at this time.
14:24
Speaker 3: All right, But sandy diaphragm is not due to microbes, right,
14:27
Speaker 3: It's due to actual visible worms.
14:29
Speaker 1: It's due to actual visible worms. They are not easy
14:31
Speaker 1: to see. So what Paget did was he took a
14:34
Speaker 1: sample and he used a hand lens and he squished
14:37
Speaker 1: it between two glass slides, and he looked at it
14:39
Speaker 1: with the hand lens, and he thought he saw something
14:41
Speaker 1: kind of wormy, but he wanted to get a better
14:43
Speaker 1: look at it, so he brought it over to the
14:45
Speaker 1: British Museum of Natural History, and he actually knocked on
14:48
Speaker 1: the door of the guy who came up with Brownie
14:50
Speaker 1: and the idea behind Brownie in Motion. So he knocked
14:53
Speaker 1: on Brown's door, and he had a microscope. He let
14:56
Speaker 1: Paget use it, and Paget noted that there was actually
14:59
Speaker 1: a worm there. Some of the worms were moving and
15:02
Speaker 1: some were not, and the ones that were not had
15:05
Speaker 1: been calcified by the human body and that's what was
15:08
Speaker 1: causing the sandy diaphragm. So when these worms die, the
15:12
Speaker 1: immune system responds by sort of like creating like a
15:16
Speaker 1: calcified casket to like walllet off from everything else, and
15:19
Speaker 1: over time that creates like hard structures, and that is
15:22
Speaker 1: what the scalpels were dulling on. So he goes and
15:25
Speaker 1: he tells a group of medical students about his finding,
15:28
Speaker 1: but he doesn't take the important next step of publishing
15:31
Speaker 1: and sharing his results more widely. The same cadaver, a
15:36
Speaker 1: sample of it, got sent to this other guy named
15:38
Speaker 1: Richard Owen, and we don't need to get into too
15:40
Speaker 1: much detail here, but he also from the same cadaver,
15:44
Speaker 1: ended up looking and seeing these worms. He wrote it up,
15:46
Speaker 1: he gave a public lecture. He's the one who got
15:48
Speaker 1: the credit. But this one cadaver produced two different people
15:52
Speaker 1: who were the first to notice that actually there were
15:55
Speaker 1: these little, tiny worms, and so it used to be
15:58
Speaker 1: called traquina. I think what which is a word for
16:00
Speaker 1: like tiny hair and spiralis is, you know, like the
16:03
Speaker 1: spiral shape, and so these are hair shaped worms that
16:06
Speaker 1: curl up in a spiral inside of cells like direphram cells.
16:10
Speaker 1: But Trickina also was a genus of flies, and so
16:14
Speaker 1: they went with Trickinella to avoid confusion. So hair like
16:18
Speaker 1: spirally things.
16:21
Speaker 3: And take us back also scientifically, like if you find
16:24
Speaker 3: worms in a body, at that point, do you have
16:27
Speaker 3: to assume that somehow the people have eaten them or
16:30
Speaker 3: they've invaded the body, or are we still in a
16:32
Speaker 3: place where like we don't understand whether life can be
16:35
Speaker 3: generated spontaneously.
16:37
Speaker 1: So we and Hook and Pasture I think they had
16:41
Speaker 1: already done their experiments at this point where you know
16:43
Speaker 1: that there's little things and you know that those little
16:45
Speaker 1: things aren't generated spontaneously, because Pasture and I think some
16:50
Speaker 1: other people as well had done those experiments where they
16:52
Speaker 1: had made those flasks that had the like bendy mouth
16:56
Speaker 1: parts so that the air couldn't sort of get in.
16:59
Speaker 1: And whenever air can't get in and you had like
17:01
Speaker 1: a nutrient broth, nothing would grow in it. But if
17:04
Speaker 1: air could get in, you would get growth. And so
17:06
Speaker 1: it's not arising spontaneously. You have to have something seating
17:09
Speaker 1: the living things. I'm sure that people had seen parasitic
17:12
Speaker 1: worms before but I don't think we had a very
17:15
Speaker 1: good handle on life cycles.
17:17
Speaker 3: All right, What exactly was new and novel about this?
17:20
Speaker 3: What did this tell us about parasites and humans and
17:24
Speaker 3: all that kind of stuff.
17:25
Speaker 1: So I don't think that this is the first parasitic
17:28
Speaker 1: disease that was ever discovered, but I think this is
17:31
Speaker 1: a problem that was attributed to a parasitic disease at
17:34
Speaker 1: this point. So like this person in particular had died
17:37
Speaker 1: of tuberculosis. I think it was a while before we
17:40
Speaker 1: realized that this was something that could kill people as
17:42
Speaker 1: opposed to just something that's a pain in the rear
17:44
Speaker 1: end when you're trying to run a scalpel through a
17:46
Speaker 1: dead person's body. But even today, if you get infected
17:49
Speaker 1: by too many of these all at once, you can die.
17:52
Speaker 1: So let's talk a little bit more about what they
17:55
Speaker 1: actually discovered when we get back from the break. Okay,
18:14
Speaker 1: So what they had discovered was trick and ellis barrellis.
18:18
Speaker 1: This is a nematode. So they've got like a hard cuticle.
18:21
Speaker 1: They kind of look like earthworms, but without the segments
18:23
Speaker 1: and the ones that we're talking about, the ones that
18:26
Speaker 1: cause trick and e loosis they're very tiny, so they're
18:29
Speaker 1: much smaller than normal earthworms. Do you feel like you've
18:32
Speaker 1: got that image in your head.
18:33
Speaker 3: I'm imagining something that looks basically like a human hair
18:36
Speaker 3: and it's curled up. Yeah, and if you zoom in
18:39
Speaker 3: on it, it looks sort of like a worm.
18:40
Speaker 1: Yeah, it comes to points at either end, but yes,
18:43
Speaker 1: kind of like a human hair, except points at the ends.
18:46
Speaker 1: And so what happens is if you eat meat that's
18:49
Speaker 1: infected by this parasite and that meat's not cooked through
18:51
Speaker 1: all the way, the parasites burst out of the cells
18:54
Speaker 1: that they've been living in. So as your body is
18:56
Speaker 1: digesting the food, it also digests the cells they've been
18:58
Speaker 1: living in and that releases them.
19:00
Speaker 3: So they've been living inside the cells. Like I'm eating pork.
19:03
Speaker 3: Then these worms are inside the cells the pig, not
19:06
Speaker 3: swimming around between the cells.
19:08
Speaker 1: Yeah, and this is not something that's super common for
19:10
Speaker 1: wormy parasites to do, but this is something that this
19:13
Speaker 1: particular species does. They live inside the cells, and they
19:16
Speaker 1: can live inside the cells for like thirty years, like
19:18
Speaker 1: incredible amounts of time.
19:20
Speaker 3: So they're smaller than like a pig cell.
19:23
Speaker 1: And they get into the pig cell, they expand the
19:26
Speaker 1: size of that cell. Oh well, get there. I'm so
19:29
Speaker 1: sorry about the next few years of your life, Daniel.
19:31
Speaker 1: And so they burst out of the cells, they find mates,
19:34
Speaker 1: they produce live smaller worms, and the smaller worms get
19:38
Speaker 1: into your bloodstream or the circulation for your lymph, and
19:42
Speaker 1: then they end up all over your body. But they
19:45
Speaker 1: can only move in and live into skeletal muscle cells.
19:51
Speaker 1: And so when they end up in like your heart
19:54
Speaker 1: or your brain, they try burrowing into those cells and
19:57
Speaker 1: then they're like, oh, this isn't home, and they borrow
20:00
Speaker 1: back out again.
20:01
Speaker 3: Because we have two different kinds of muscle cells, right,
20:03
Speaker 3: smooth and skeletal. Is that right?
20:05
Speaker 1: Three types cardiac, skeletal and smooth.
20:09
Speaker 3: Oh all right, cool? So why can they only live
20:12
Speaker 3: in one particular kind of muscle? Is the shape of
20:14
Speaker 3: the cell, the size of the cell, the kind of
20:15
Speaker 3: food they get inside or.
20:17
Speaker 1: I don't think we know the answer to that. But
20:18
Speaker 1: they do end up manipulating these cells. They are born
20:22
Speaker 1: about a week after you eat the infected meat, and
20:24
Speaker 1: they're going on this journey. And so about a week
20:26
Speaker 1: after you eat the infected meat, this is when you're
20:29
Speaker 1: at the highest risk of dying because if you ate
20:31
Speaker 1: a lot of parasites in that meat, they're all having babies,
20:35
Speaker 1: they're all releasing babies, and those babies are like maybe
20:39
Speaker 1: if they end up in your brain, destroying a bunch
20:41
Speaker 1: of brain cells or destroying a bunch of cardiac cells.
20:44
Speaker 1: And at this point you're often given medication to reduce inflammation,
20:48
Speaker 1: because that's a big part of what is causing trouble here,
20:51
Speaker 1: the inflammation as a result of the parasites moving around,
20:53
Speaker 1: And sometimes you're given anti parasite medication. But this is
20:57
Speaker 1: the most dangerous phase of the process.
20:59
Speaker 3: And in order to be a risk of like dyeing,
21:01
Speaker 3: you must need to have lots and lots of these parasites.
21:04
Speaker 3: Can one worm or two worms generate like an avalanche
21:08
Speaker 3: of these things? Or do you need to eat a
21:10
Speaker 3: lot of the meat you have like a big initial population.
21:12
Speaker 1: Yeah, the more that you eat initially, the worst shape
21:15
Speaker 1: you're going to be in. So if you just happen
21:17
Speaker 1: to eat one or two cells that have the parasite,
21:20
Speaker 1: you're probably gonna be fine.
21:21
Speaker 3: You're still going to have parasites inside you. You're just
21:23
Speaker 3: not going to die. That's what you call it fine.
21:26
Speaker 1: I mean, for most of our revolutionary history, that would
21:28
Speaker 1: have been lucky, just one or two parasites in you.
21:31
Speaker 1: But yes, it won't be a dire situation, I guess.
21:35
Speaker 1: But so when these parasites do find the cells, they're
21:38
Speaker 1: looking for the skeletal muscles they burrow in and now
21:42
Speaker 1: this is when they start manipulating the cell. So they
21:44
Speaker 1: call the cell a neur cell. They like secrete some
21:47
Speaker 1: stuff that gets rid of the parts of the cell
21:49
Speaker 1: that they don't need. They start growing and expanding. The
21:52
Speaker 1: cell starts getting bigger, and then around the cell, I
21:56
Speaker 1: think it doesn't recruit the kind of vessels that bring
21:58
Speaker 1: oxygenated blood because inside the cell you end up with
22:02
Speaker 1: an anaerobic environment. I don't know why that's necessary, But
22:05
Speaker 1: so they start bringing the kinds of cells that take
22:08
Speaker 1: deoxygenated blood away. But in this way, the nurse cell
22:12
Speaker 1: delivers nutrients and removes waste, and so the parasites are
22:17
Speaker 1: able to manipulate the cells to become nice homes and
22:20
Speaker 1: to do things like remove waste and feed them. So
22:23
Speaker 1: we don't really understand how this happens, but it does.
22:26
Speaker 1: And Dixon de Pomier wrote this book called Parasites People
22:28
Speaker 1: in Plowshares, where he argues that if we could understand
22:31
Speaker 1: how nurse cells work, we could maybe understand like better
22:34
Speaker 1: ways of like delivering insulin and stuff like that. And
22:37
Speaker 1: so he's really interested in trying to like physiologically understand
22:41
Speaker 1: what's happening here. But it's a complicated system.
22:43
Speaker 3: So they really have taken over the cell and refashioned
22:46
Speaker 3: it for their own use. It's no longer doing the
22:48
Speaker 3: original thing you had that cell for. It's not basically
22:50
Speaker 3: just like a homestead for these worms.
22:53
Speaker 1: Yep, it's kind of amazing. I think that they've managed to, like,
22:55
Speaker 1: you know, evolve to do this.
22:57
Speaker 3: I think it's super amazing when they manipulate their environment
23:00
Speaker 3: respond in a certain way to take advantage of it. Obviously,
23:03
Speaker 3: you know this is just evolutionary, right, there's no like
23:05
Speaker 3: intentional design here. They're not like engineers where they're thinking
23:08
Speaker 3: about what to do. But they found this strategy. Why
23:12
Speaker 3: haven't humans responded in an evolutionary sort of way to
23:16
Speaker 3: create new defenses, Like, obviously this is bad if it
23:18
Speaker 3: kills you, or even if it doesn't kill you, it
23:20
Speaker 3: must be bad for you because it's sapping your energy.
23:24
Speaker 3: Do humans have defenses against this or we just like
23:26
Speaker 3: total suckers for these worms.
23:28
Speaker 1: Well, so some of the worms die and the ones
23:30
Speaker 1: that die they get calcified. And I think probably some
23:33
Speaker 1: of them are dying because of an appropriate immune response.
23:37
Speaker 3: I'm glad to here's something's happening in the inside to
23:39
Speaker 3: push back.
23:39
Speaker 1: Yeah, yeah, we're doing something. But y know, so for
23:42
Speaker 1: a lot of parasites, the deal is that they, through
23:45
Speaker 1: this evolutionary arms race, have just found ways to evade
23:47
Speaker 1: the immune system, to just make the immune system things
23:49
Speaker 1: it's not even there. And then other times it's more
23:52
Speaker 1: about like and I'm going to make this sound super anthropomorphic,
23:55
Speaker 1: and it's not like a decision that the body's making,
23:57
Speaker 1: like it's thinking about it like a person. But this
23:59
Speaker 1: is a process overtionary time. But so these worms that
24:02
Speaker 1: are living in the nurse cells, is it worse for
24:04
Speaker 1: the body to deliver a tiny amount of energy to
24:07
Speaker 1: these teeny tiny little worms or to kill the worms
24:10
Speaker 1: and calcify it. And if it's in your diaphragm, you know,
24:13
Speaker 1: so like that sandy diaphragm. Yeah, it's a problem for
24:15
Speaker 1: the scalpel. But probably a diaphragm that's that hard, isn't
24:19
Speaker 1: doing a very good job of like helping you breathe.
24:23
Speaker 1: And so if you end up with all of these
24:24
Speaker 1: calcified muscles, and when a parasite dies, it usually kicks
24:27
Speaker 1: off an inflammatory response. And so I think over evolutionary time,
24:32
Speaker 1: the trick isn't attack all the parasites that you have
24:35
Speaker 1: with your maximum mobility, because when you initiate an immune response,
24:40
Speaker 1: that often causes damage to the host as well. And
24:42
Speaker 1: so I think it's a balancing act between what do
24:44
Speaker 1: I just ignore and what do I have all out
24:47
Speaker 1: war against.
24:48
Speaker 3: I don't know, Kelly, I think you're just a shill
24:49
Speaker 3: for big parasite. I mean, you're telling me I should
24:52
Speaker 3: happily live along with these things that have like squatting
24:56
Speaker 3: in my cells. You're like, isn't it just best for
24:59
Speaker 3: everybody if you you just give in and give up
25:02
Speaker 3: some of your energy. Like, I don't know, I think
25:04
Speaker 3: we're in all out war with these things.
25:06
Speaker 1: There are some unpleasant people in my life, and I
25:08
Speaker 1: think my life is better for ignoring them than for
25:11
Speaker 1: like trying to attack back. And you know, I don't
25:13
Speaker 1: think it's that different with the worms and you know,
25:15
Speaker 1: we should have a whole episode one day on this
25:18
Speaker 1: old friends or hygiene hypothesis. Are you familiar with this idea?
25:21
Speaker 3: Yeah.
25:22
Speaker 1: The idea is basically that, like, we've had these organisms
25:24
Speaker 1: in our body through enough evolutionary time that our immune
25:28
Speaker 1: systems have come to sort of like expect them to
25:30
Speaker 1: be there, and now they're sort of used as cues
25:32
Speaker 1: for how our immune systems should work and how our
25:34
Speaker 1: immune system identifies self from not self. These things don't
25:38
Speaker 1: always go in the direction you'd think I wouldn't want
25:40
Speaker 1: to have any worms in my body, but you know
25:42
Speaker 1: it's also positible. My body is just like it's not
25:44
Speaker 1: worth the effort you just ignore.
25:46
Speaker 3: Yeah, and Katrina is big on not classifying microbes, some
25:50
Speaker 3: of them as good or bad because they all play
25:52
Speaker 3: different roles and it's complicated, and you know, you might
25:56
Speaker 3: imagine you don't want to be infected, but obviously lots
25:58
Speaker 3: of microbes are essential for your life, the fermentation that
26:01
Speaker 3: happens in your gut, all that kind of stuff. Is
26:03
Speaker 3: it possible that parasites like these worms are playing some
26:07
Speaker 3: positive role that we're benefiting from. I mean, you call
26:10
Speaker 3: them a parasite, which implies that we're not getting anything.
26:12
Speaker 3: There's no commensural reaction here. But are there any benefits
26:16
Speaker 3: to having these worms live inside of us?
26:18
Speaker 1: I don't think there's any documented benefit from having Trickenellis
26:21
Speaker 1: barrellus inside of you. There are some other parasites that
26:24
Speaker 1: people have been experimenting with where when you infect people,
26:29
Speaker 1: like their hay fever symptoms go away, or their crone's
26:33
Speaker 1: disease symptoms become less severe, or their MS goes into
26:37
Speaker 1: remission or whatever the right word is for that. But
26:40
Speaker 1: those studies are super complicated. Sometimes you get good results,
26:44
Speaker 1: sometimes you don't. It seems to depend on the parasite
26:47
Speaker 1: genome or maybe the exact person's genome and the exact
26:50
Speaker 1: kind of problem they have. And I think science is
26:52
Speaker 1: like really working through digging through that right now, and
26:55
Speaker 1: right now we're at a like what is happening phase,
26:59
Speaker 1: But we should invite an expert on one day to
27:01
Speaker 1: talk about that.
27:02
Speaker 3: I'm just trying to get mentally prepared because you know,
27:04
Speaker 3: I've learned now the bacteria it can be good for you,
27:06
Speaker 3: and even leeches can be good for you. So hey,
27:08
Speaker 3: maybe in the future we'll all be intentionally injecting worms
27:12
Speaker 3: into our children.
27:13
Speaker 1: There are a community of people who are intentionally infecting
27:15
Speaker 1: themselves with parasites right now. I think most of them
27:18
Speaker 1: are not doing that to their children, I hope. But
27:22
Speaker 1: in my mind, the ideal thing isn't that we all
27:24
Speaker 1: take like five hookworms for breakfast and call it a day,
27:26
Speaker 1: but that we figure out what cues the parasites are
27:30
Speaker 1: giving our immune system, and then we can like take
27:32
Speaker 1: a probiotic pill or something that like replicates those cues
27:36
Speaker 1: so we don't actually have to have the parasites there.
27:37
Speaker 1: But I agree with Katrina that I think we are
27:40
Speaker 1: at a point where dichotomizing things as good and bad,
27:43
Speaker 1: we're realizing sometimes it's a little bit more complicated and
27:46
Speaker 1: it depends on context.
27:47
Speaker 3: And I think the point you made is really interesting
27:49
Speaker 3: that we can learn from them how to manipulate our
27:52
Speaker 3: own bodies. Like if they have spent millions of years
27:55
Speaker 3: evolving strategies to pull chemical levers inside the body, we
28:00
Speaker 3: can take advantage of that, right. If we understand the
28:02
Speaker 3: techniques that they have stumbled into, we can maybe use
28:05
Speaker 3: them intentionally to understand the workings of our own system.
28:08
Speaker 1: Yeah. Yeah, sometimes the parasites that manipulate host behavior. We
28:11
Speaker 1: sometimes refer to them as evolutionary neuroscientists. And there's you know,
28:15
Speaker 1: like a whole group of people like me who write
28:17
Speaker 1: our NSF grants about how we can understand host behavior
28:19
Speaker 1: better by trying to figure out what parasites have quote
28:22
Speaker 1: unquote learned through natural selection. All of this across all
28:26
Speaker 1: these years.
28:26
Speaker 3: So these guys set up a home in these nurse cells,
28:29
Speaker 3: make them work for them. How long do they hang out? Like,
28:33
Speaker 3: do they live as long as the cells live? Do
28:35
Speaker 3: they have like generations and generations of worms inside one cell?
28:39
Speaker 3: Or does a single worm last a long time?
28:42
Speaker 1: So there's no reproduction happening at this stage. But worms
28:45
Speaker 1: can live it looks like for twenty five plus years.
28:47
Speaker 3: Twenty five years. Oh yeah, gosh, so they can vote
28:51
Speaker 3: and you know, buy alcohol and stuff like this.
28:53
Speaker 1: Yeah, absolutely, because that's what they're doing. But no, they
28:55
Speaker 1: live for a really long time. And I mean they've
28:57
Speaker 1: got like a nice setup. You know, food is being
28:58
Speaker 1: delivered to them, their wastes are being removed, so yeah,
29:01
Speaker 1: they can live for a really long time. But they're
29:02
Speaker 1: not reproducing. They're just like biding their time until the
29:06
Speaker 1: muscles that they live in get eaten by something else.
29:09
Speaker 3: And are they squirming around a lot? Because for some
29:12
Speaker 3: reason that makes them a lot worse. Like if you're
29:14
Speaker 3: just quietly hanging out inside my cell and stealing some food, okay,
29:17
Speaker 3: but if you're like squirming around, then it's Oh, I
29:20
Speaker 3: just can't tolerate that.
29:21
Speaker 1: You know, I would like to exercise every day. So
29:23
Speaker 1: I guess I hope that they're like running laps and
29:25
Speaker 1: their little nurse cells. But I think they're generally not
29:28
Speaker 1: moving much. And if they are, you're not feeling it.
29:30
Speaker 3: See, you're pro parasite. There you are again like advising
29:33
Speaker 3: the parasites how to live their best life inside people.
29:36
Speaker 1: Well, you know, we all need to stay healthy. So
29:40
Speaker 1: you know, you might be asking yourself, if you want
29:42
Speaker 1: to avoid being a track for parasites, how do you
29:46
Speaker 1: do that?
29:46
Speaker 3: Yes, tell me.
29:47
Speaker 1: For a long time it was difficult. So most of
29:49
Speaker 1: us get this parasite from pork, and so pigs get infected.
29:53
Speaker 1: It's in the pigs muscles. And if you eat pork
29:56
Speaker 1: that hasn't been cooked through enough, that's how you get infected.
29:59
Speaker 1: And pork, you know, in the eighteen eighties, the United
30:02
Speaker 1: States was like a world exporter of pork. It was
30:05
Speaker 1: a huge industry for US, and it ended up being
30:07
Speaker 1: a big problem for US because Europeans decided that because
30:11
Speaker 1: we weren't checking for trick and ella, we weren't checking
30:14
Speaker 1: for this parasite, that we were causing a bunch of
30:16
Speaker 1: trick and alsis outbreaks in Europe. And so for a
30:19
Speaker 1: while they stopped importing pork from US, and this was
30:24
Speaker 1: a big problem for our industry. Some Americans went over
30:27
Speaker 1: there and they were like, no, and they figured out that, like, no,
30:30
Speaker 1: it's not necessarily our pork that's causing the problem. Like
30:33
Speaker 1: maybe maybe sometimes it's American pork that's the problem, but
30:36
Speaker 1: like it's not like all of our pork is wormy.
30:38
Speaker 1: But you know, it was a good goal to try
30:40
Speaker 1: to reduce the worminess of our meat. And so how
30:43
Speaker 1: did we do that?
30:44
Speaker 3: But wait, hold on a second, why pork? Like do
30:46
Speaker 3: these parasites prefer pig cells to cow cells for some reason?
30:50
Speaker 3: Do cows have the kind of muscles that they can't
30:53
Speaker 3: get inside? Why pork?
30:54
Speaker 1: Okay, so part of it has to do with the
30:56
Speaker 1: animal's diet. So pigs eat everything like a thing of
31:00
Speaker 1: getting pigs on our farm so that all of our
31:02
Speaker 1: food waste goes into pigs. But then I couldn't turn
31:04
Speaker 1: them into bacon because they'd be like friends. I'd probably
31:06
Speaker 1: name them wilburm. So pigs eat everything, including other pigs.
31:11
Speaker 3: Pigs are cannibals, yep.
31:12
Speaker 1: Pigs are cannibals. Yep. I need to be excited about that.
31:15
Speaker 1: So when a pig dies, another pig will eat its
31:18
Speaker 1: infected muscles, and then they'll get infected. Oh, so part
31:21
Speaker 1: of it has to do with diet. There were also
31:23
Speaker 1: some like rodents, who would eat dead pigs, and then
31:26
Speaker 1: other pigs would eat the rodents, and so for a while,
31:28
Speaker 1: rodents were part of the transmission cycle here. Cows tend
31:32
Speaker 1: to not eat meat, but like horses, can get infected.
31:36
Speaker 1: And horses don't usually eat meat, but sometimes they will,
31:40
Speaker 1: so like a lot of animals that we think of
31:42
Speaker 1: as non meat eaters, will eat meat every once in
31:45
Speaker 1: a while if you give it to them and they're
31:46
Speaker 1: in the right mood. And so there have been cases
31:48
Speaker 1: of horses getting infected.
31:50
Speaker 3: We even learned on the podcast recently that bees sometimes
31:53
Speaker 3: eat meat, right.
31:54
Speaker 1: That's right, yes, yes, meat, honey, m m yeah, And
31:58
Speaker 1: so I think the reason that cows often don't get
32:00
Speaker 1: infected is because they're just not eating meat. So trick
32:03
Speaker 1: Andella spiralis is one trick and Ella species. There are
32:06
Speaker 1: other trick and Ella species that seem to specialize on
32:09
Speaker 1: other animals. There's like in the United States, bears and
32:13
Speaker 1: moose and wild boars, some of them can get infected
32:17
Speaker 1: by trick and Ella spurrells. But there's also other trick
32:20
Speaker 1: and Ella species that are more common in nature that
32:23
Speaker 1: they can get infected with. But then we can get
32:25
Speaker 1: infected by those if we don't cook the meat through.
32:28
Speaker 1: And so there is some chance that I carry some
32:32
Speaker 1: trick and Ella in me because I ate bear once
32:34
Speaker 1: that I don't think was cooked through.
32:36
Speaker 3: All the way you ate a bear? What I had
32:38
Speaker 3: to hear that story? When did you have a bear not.
32:41
Speaker 1: A whole bear? I was working with some folks in
32:45
Speaker 1: the Wisconsin Department of Natural Resources and they were nice
32:48
Speaker 1: enough to invite us to their annual social gathering and
32:52
Speaker 1: a bunch of people brought stuff that they had hunted,
32:54
Speaker 1: and there was barbecue bear. And so I mean, I've
32:58
Speaker 1: eaten bear. I'm gonna assume they cooked it through all
33:01
Speaker 1: the way. But I've also eaten smoked moose heart. Oh,
33:06
Speaker 1: but it shouldn't be in the cardiac muscles, so that
33:08
Speaker 1: should be fine because it's in skeleton muscles.
33:10
Speaker 3: Yeah, there you go, it's smoked moose heart.
33:12
Speaker 1: Knowing is half the battle.
33:13
Speaker 4: You know.
33:14
Speaker 1: The smoked moose heart was gross, Like when it got
33:15
Speaker 1: pulled out of the bag, it still had like fat
33:19
Speaker 1: on top of the heart. But it was like a
33:21
Speaker 1: collaborator of mine who was from a part of the
33:23
Speaker 1: world where this was. Anyway I pushed.
33:26
Speaker 3: Through, You're going to turn me into a vegetarian killing.
33:28
Speaker 1: Again, right back to your vegetarian root exactly.
33:32
Speaker 3: Here we go.
33:33
Speaker 1: So let's back up. Okay, so you know you can
33:34
Speaker 1: get it from pork, but you don't get it from
33:36
Speaker 1: pork in the United States much anymore. So what's changed.
33:40
Speaker 1: So in the nineteen fifties, we made it so that
33:44
Speaker 1: people were no longer allowed to feed their farmed pigs
33:48
Speaker 1: uncooked garbage, which is such a gross phrase to hear.
33:52
Speaker 3: I think you have to cook your garbage if you're
33:54
Speaker 3: going to feed it to pigs.
33:55
Speaker 1: Yeah, So, like you know, nowadays, factory farms don't feed
33:58
Speaker 1: pigs anything you would just call garbage. I mean, I
34:00
Speaker 1: guess maybe people would want to call it garbage, but
34:02
Speaker 1: it's not actually garbage the way these animals were being
34:05
Speaker 1: fed garbage before. But for a while the change was
34:07
Speaker 1: just you had to cook it through, and if you
34:08
Speaker 1: cook it through enough, then any of the effective stages
34:11
Speaker 1: of the parasites are dead. And so that was a
34:13
Speaker 1: stage of improvement.
34:15
Speaker 3: All right, So barbecued garbage is okay, or slow roasted
34:18
Speaker 3: garbage as.
34:19
Speaker 1: Long as the internal temperature in the middle of the
34:22
Speaker 1: garbage reaches one hundred and sixty five degrees fahrenheit, yes,
34:24
Speaker 1: you're probably fine.
34:26
Speaker 3: Maybe a souvied then, because that's really good temperature control.
34:28
Speaker 3: Souvid garbage that's where they serve at pig restaurants.
34:31
Speaker 1: Oh so disgusting. So like, up until nineteen eighty five,
34:35
Speaker 1: we weren't really sure how pigs were mostly getting infected.
34:38
Speaker 1: But you know, we've talked about how cannibalism and rats
34:41
Speaker 1: contribute to infection. That was also like, sometimes if pigs
34:45
Speaker 1: and wildlife were interacting, I think most often the pigs
34:48
Speaker 1: were infecting the wildlife, but sometimes the wildlife could infect
34:51
Speaker 1: the pigs. But once we sort of figured all of
34:53
Speaker 1: this stuff out, we were able to say, like, Okay,
34:56
Speaker 1: first of all, you have to make sure your pigs
34:58
Speaker 1: aren't able to eat the other pigs if they die.
35:01
Speaker 1: You have to make sure you don't have any rats
35:04
Speaker 1: in with your pigs, which I'm sure is hard.
35:06
Speaker 3: Yeah, that sounds hard because rats are everywhere.
35:08
Speaker 1: Oh my gosh. Yes, we live on a farm. Rats
35:10
Speaker 1: are everywhere. It's hard to keep them out, but you
35:12
Speaker 1: need to make a good effort to do it.
35:14
Speaker 3: Well, let me ask you, how do you feel about
35:15
Speaker 3: the rats? Because I have this policy no rats inside
35:18
Speaker 3: the house, but outside the house. Like, hey, you guys
35:21
Speaker 3: were here before us. What am I going to do
35:23
Speaker 3: kill all the rats? That's impossible?
35:25
Speaker 1: Well, okay, so the rats that we had in our
35:27
Speaker 1: chicken coop were an invasive species, so they didn't really
35:31
Speaker 1: belong there. These were like the lab rats, Norwegian rats
35:34
Speaker 1: that had gotten out, and rats like usually I agree,
35:38
Speaker 1: but so that we have really stupid chickens, and like
35:41
Speaker 1: the chickens would be eating at their feeder and the
35:43
Speaker 1: rats would be like right next to them eating and
35:45
Speaker 1: they just kind of look at them and be like hey, Frank,
35:47
Speaker 1: and they wouldn't do anything. But so then the rats
35:49
Speaker 1: were living in the rafters above and they were just
35:52
Speaker 1: like defecating an incredible amount.
35:55
Speaker 3: They do that.
35:55
Speaker 1: They do that, and there are some diseases you can
35:58
Speaker 1: get from rat feces and from mouth hauntavirus. Yeah, right, exactly.
36:02
Speaker 1: And so if it's just like, yeah, I try to
36:05
Speaker 1: never kill wildlife, because I agree you were here first.
36:08
Speaker 1: But when it's like, well, if my daughter goes out
36:10
Speaker 1: to bring the chickens food and she's gonna get haunt virus,
36:13
Speaker 1: like we've crossed the line and we have to get
36:15
Speaker 1: rid of the rats.
36:16
Speaker 3: Also, wait, you live in Virginia, which is not that
36:19
Speaker 3: far from the NIH, right, and you're talking about rats
36:23
Speaker 3: that have escaped from labs. Are you basically living the
36:26
Speaker 3: rats of nim That was.
36:28
Speaker 1: A great movie. These rats, they are the species that
36:31
Speaker 1: we use in the lab. I don't know that they
36:33
Speaker 1: escaped from the lab. They could have just like come
36:36
Speaker 1: off of ships or something.
36:37
Speaker 3: Keep telling yourself that science has made.
36:40
Speaker 1: Some mistakes, no doubt about it. I'll own up to that.
36:43
Speaker 3: Well, we had rats as pets once, and rats are wonderful,
36:46
Speaker 3: wonderful pets. They're smart, they're affectionate, they're really cute. They
36:50
Speaker 3: do poop everywhere though, Yeah, that is definitely a problem.
36:53
Speaker 1: I also had rats as pets when I was a kid,
36:55
Speaker 1: and I thought about getting one again the other day
36:58
Speaker 1: because I did. Used to love just having like a
36:59
Speaker 1: little on my shoulder and they make this cute little noises. Yeah,
37:03
Speaker 1: I like rats a lot.
37:04
Speaker 3: My daughter would bike around the neighborhood with a rat
37:06
Speaker 3: in her hood of her hood, riding along with her.
37:09
Speaker 3: It was super cute. Yeah, anyway, you're saying, if you
37:12
Speaker 3: have pigs and rats, try to keep the pigs from
37:14
Speaker 3: eating the rats.
37:15
Speaker 1: Yes, try to keep the pigs from eating the rats.
37:17
Speaker 1: And so once we figured this stuff out, it became
37:20
Speaker 1: clear what you needed to do to keep the pigs
37:23
Speaker 1: from getting infected. And once you knew what you needed
37:26
Speaker 1: to do, you could pass laws to make sure that
37:28
Speaker 1: people are doing these things. And by putting in the
37:31
Speaker 1: right sort of like procedures in place and then coming
37:34
Speaker 1: up with some better ways to test meat to see
37:36
Speaker 1: if it's working, we have managed to mostly eradicate this
37:40
Speaker 1: parasite in pork from factory farm amazing, but there's still
37:46
Speaker 1: some ways that you can get it, which we'll talk
37:48
Speaker 1: about after the break.
37:50
Speaker 3: More nightmere fuel, don't worry.
37:52
Speaker 1: That's right. We were just talking about how pigs from
38:11
Speaker 1: factory farms in the United States tend to not have
38:14
Speaker 1: this parasite anymore. And actually in twenty twenty four there
38:17
Speaker 1: was a study where they sampled three million pigs and
38:22
Speaker 1: none of those pigs from factory farms had trichinella.
38:25
Speaker 3: Amazing.
38:26
Speaker 1: Wow, that is incredible. Like if you think that we
38:28
Speaker 1: have gone from one in six people in New England
38:32
Speaker 1: having this parasite infection, which can kill you sometimes, to
38:37
Speaker 1: testing three million pigs and none of them have it,
38:40
Speaker 1: that's an incredible decline.
38:41
Speaker 3: That means all those people who were infected when they died,
38:44
Speaker 3: nobody ate them and then absorbed the infection, right, including
38:48
Speaker 3: the pigs.
38:48
Speaker 1: That's right. Yes, I should have known you were going
38:50
Speaker 1: to go there. My bad, But yes, that means that
38:53
Speaker 1: there's not a lot of human cannibalism going on. Good news.
38:56
Speaker 3: And of course I'm going to ask if pigs can
38:59
Speaker 3: get from eating other pigs, that means humans could get
39:01
Speaker 3: it from eating other humans, right yep, yeah, okay, one
39:03
Speaker 3: more reason not to eat your children.
39:05
Speaker 1: Yes, yeah, well, you know, if they're young enough, maybe
39:08
Speaker 1: they haven't been exposed and they move it on.
39:11
Speaker 3: When their meat is still so tender.
39:13
Speaker 1: Oh God, why do we do this?
39:16
Speaker 2: All? Right?
39:17
Speaker 1: So, now there's about fifteen confirmed cases in the United
39:19
Speaker 1: States a year, which is an incredible drop, and there's
39:22
Speaker 1: about ten thousand cases recorded throughout the world per year.
39:27
Speaker 1: And I think a lot of those cases are in
39:29
Speaker 1: places like China where they eat a lot of pork,
39:33
Speaker 1: but maybe they don't have the same sort of procedures
39:36
Speaker 1: in place to make sure that the pigs aren't eating
39:38
Speaker 1: each other or being exposed to rats. And so there
39:40
Speaker 1: are other places in the world that you can go
39:43
Speaker 1: where if you eat pork you could get infected.
39:46
Speaker 3: So how's it happening in the US if there were
39:48
Speaker 3: no examples in all of those pigs where people get
39:51
Speaker 3: and they're just getting it from the wild again, or
39:53
Speaker 3: they're eating weird smoked moose hearts or something.
39:57
Speaker 1: So I think a lot of people do get it
39:59
Speaker 1: from animal that they hunt. So you can get it
40:02
Speaker 1: from bears, you can get it from moods, you can
40:03
Speaker 1: get it from wild boar. And also, you know, if
40:06
Speaker 1: people have pigs in their backyard, they are not necessarily
40:09
Speaker 1: following all of the rules that like the USDA mandates.
40:14
Speaker 1: So it could be that their pigs are encountering wild
40:17
Speaker 1: animals that they're eating or then eating each other, and
40:20
Speaker 1: so you could get it from like backyard pigs. The
40:23
Speaker 1: good news is if you cook your meat where the
40:27
Speaker 1: inside reaches I think it's one hundred and forty five
40:30
Speaker 1: degrees fahrenheit, then the parasite dies. The bad news is
40:35
Speaker 1: if you freeze the meat, even for something like two months,
40:38
Speaker 1: that doesn't necessarily kill Trick.
40:40
Speaker 3: And Ella w Yeah, can survive freezing.
40:43
Speaker 1: It's amazing. Yeah, So like there have been cases where
40:45
Speaker 1: meat has been frozen and two months later it's come
40:48
Speaker 1: out of the freezer and when it thaws, those worms
40:50
Speaker 1: start moving around again. This is mostly the wild strains
40:54
Speaker 1: or the wild species. Maybe it's not too surprising because
40:57
Speaker 1: like bears can hibernate, they get really cold. But still,
41:00
Speaker 1: the fact that they can freeze, that's amazing because bears
41:03
Speaker 1: aren't freezing through when they're hibernating.
41:04
Speaker 3: Yeah, And I thought that most cells when they freeze,
41:07
Speaker 3: they burst because water expands as it freezes. So how
41:10
Speaker 3: do these guys survive it?
41:12
Speaker 1: I mean, I'm guessing some of them do have nurse
41:14
Speaker 1: cells that burst and they die. But most of the
41:17
Speaker 1: food that we plan on eating we freeze quickly because
41:20
Speaker 1: when those cells burst, that food doesn't taste as good.
41:24
Speaker 1: And so like you want to freeze your food quickly
41:27
Speaker 1: so the cells don't burst, because that's a better way
41:29
Speaker 1: to eat a hamburger or a bear steak. So I think,
41:32
Speaker 1: you know, the parasites are benefiting from that and they
41:35
Speaker 1: can survive. And then also if you prepare jerky out
41:39
Speaker 1: of bear meat, that processes preparing the jerky doesn't always
41:42
Speaker 1: kill the parasites. These parasites, you think about it, like
41:45
Speaker 1: they transmit when the animal that they die in gets
41:49
Speaker 1: eaten by something else, and that doesn't always happen immediately.
41:52
Speaker 1: So they need to be able to like survive the
41:53
Speaker 1: death of the animal for a while and persist in
41:56
Speaker 1: the environment to increase the probability that they get eaten
41:59
Speaker 1: by something. Yes, yeah, so most of the cases in
42:02
Speaker 1: the United States come from wild animals that have been
42:05
Speaker 1: killed and then not cooked through all the way. In
42:07
Speaker 1: other parts of the world, you can get it from
42:08
Speaker 1: pork because they don't have the like public health procedures
42:12
Speaker 1: that we have in place here in the United States.
42:15
Speaker 1: But I'm excited about this system because it's a pretty
42:18
Speaker 1: clear example where doing the basic work to understand the
42:21
Speaker 1: life cycle of the parasite and then putting that information
42:25
Speaker 1: in the hands of people who can like set up
42:27
Speaker 1: procedures was able to save I think many many lives, Yeah,
42:31
Speaker 1: and also just be less creepy, Like maybe not a
42:33
Speaker 1: lot of people were going to die, but it's really
42:35
Speaker 1: nice to know that we don't have like parasites running
42:38
Speaker 1: laps in our diaphragms in the United States.
42:43
Speaker 3: So you're a parasitologist, you know, the cutting edge of
42:47
Speaker 3: parasite science. We've mostly told the historical story today, but like,
42:52
Speaker 3: what are people working on right now? If you go
42:54
Speaker 3: to trichinosis conference, what are the presentations about, what are
42:57
Speaker 3: the questions that people are asking.
42:59
Speaker 1: Yeah, so one of the main topics here is trying
43:03
Speaker 1: to figure out when an outbreak happens. So there are
43:06
Speaker 1: still outbreaks. I was listening to someone's talk the other
43:08
Speaker 1: day and it was somewhere in Scandinavia there was an
43:11
Speaker 1: outbreak on farms and it showed up in a couple
43:14
Speaker 1: different farms, and so they were collecting samples of the
43:18
Speaker 1: parasite and then they were genotyping it. So they were
43:20
Speaker 1: getting like the whole genome of the parasite, and they
43:23
Speaker 1: were trying to use that information to find out did
43:26
Speaker 1: the parasite jump from a wild animal, you know, where
43:30
Speaker 1: the pig's able to go out in the field one
43:31
Speaker 1: day and they ate a wild animal and that's how
43:33
Speaker 1: they got infected. But by figuring out what species or strain,
43:38
Speaker 1: then they can try to figure out like where the
43:40
Speaker 1: procedure for keeping this parasite out of our food system,
43:43
Speaker 1: like where that broke down. And so they're using genetic
43:46
Speaker 1: information to sort of do the tracing stuff here. They're
43:48
Speaker 1: also still trying to figure out how this nurse cell works,
43:53
Speaker 1: you know, how does it manage to manipulate the human
43:55
Speaker 1: body into essentially like waiting on it hand and foot
43:59
Speaker 1: without killing it. And you know, also like wildlife ecologists
44:02
Speaker 1: are probably interested in what trick and ella is doing
44:04
Speaker 1: to like wild bear populations and stuff like that. So
44:07
Speaker 1: I think those are the main topics we're dealing with
44:10
Speaker 1: right now.
44:10
Speaker 3: So this all sounds surprisingly positive. You're saying this is
44:13
Speaker 3: a success story. Is this typical killing or is the
44:16
Speaker 3: wider world of parasites a darker world?
44:19
Speaker 1: Well, the wider world of parasites can be pretty dark.
44:23
Speaker 1: So this was a nice case where we figured out
44:25
Speaker 1: how the parasite was transmitted. It was pretty clear what
44:27
Speaker 1: we needed to do, and it wasn't that hard to
44:29
Speaker 1: implement the changes. But there's other parasites where we know
44:33
Speaker 1: what it would take to eradicate the infection. But like
44:37
Speaker 1: for example, bringing the appropriate sanitation measures to the people
44:41
Speaker 1: who need it has just proven to be something that
44:43
Speaker 1: we can't seem to do yet. And so the next
44:46
Speaker 1: time we talk about this wormy world of ours, we're
44:48
Speaker 1: gonna be talking about nematodes. And today we talked about
44:50
Speaker 1: anematode too, but we're gonna be talking about nematodes that
44:53
Speaker 1: you can get because they burrow through your skin when
44:56
Speaker 1: you're walking in soil that's carrying these effective stages.
44:59
Speaker 3: Oh no, you don't even need to make bad eating decisions.
45:02
Speaker 3: You can just be going.
45:03
Speaker 1: For a walk, or you can be gardening. They're able
45:06
Speaker 1: to just sort of burrow through your skin. So we
45:08
Speaker 1: will talk about soil transmitted helmets which have been stubborn
45:12
Speaker 1: and hard to eradicate. The next time we visit this
45:15
Speaker 1: warming world.
45:16
Speaker 3: There's always more nightmare fuel waiting for you in Biology.
45:20
Speaker 1: And Kelly's got it ready for you.
45:23
Speaker 3: Thanks everyone, tune in next time.
45:32
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