WEBVTT - Ep 96 Tapeworm: We encyst you listen 0:00:03.400 --> 0:00:08.600 Professor Yokogawa casually spoke to me jokingly, saying, Yoshino, as 0:00:08.720 --> 0:00:11.920 Tenia solium is present in your home, Okinawa, how about 0:00:11.920 --> 0:00:16.760 doing experimental infection for your PhD study. Of course, Yokogawa 0:00:16.800 --> 0:00:20.520 and I knew epilepsy and neurocysta sercosis could be caused 0:00:20.520 --> 0:00:24.560 by accidental ingestion of eggs of this parasite. At first, 0:00:24.760 --> 0:00:28.480 I was very nervous about accidental neurosiste sercosis in my brain, 0:00:28.640 --> 0:00:32.159 et cetera. However, it was an exceptionally big chance for 0:00:32.200 --> 0:00:35.560 me to do an experimental infection. Even if I had 0:00:35.640 --> 0:00:39.279 a serious health problem or sudden death, My data might 0:00:39.400 --> 0:00:43.519 contribute to this topic that nobody has done and therefore 0:00:43.680 --> 0:00:48.680 be highly informative for future advances in parasitology. Then I 0:00:48.760 --> 0:00:51.839 felt some power inside of my body which pushed me 0:00:51.960 --> 0:00:55.320 to do it right then, and I swallowed three sister serki. 0:00:55.960 --> 0:00:57.680 When I came back to my home in the evening, 0:00:57.840 --> 0:01:01.600 I told this mission to my wife. She was very surprised, 0:01:02.040 --> 0:01:05.400 but tried to understand my hard academic life and took 0:01:05.440 --> 0:01:08.720 more care of my health as my purpose was observing 0:01:08.760 --> 0:01:12.679 gravid proglotids and feces. I stopped using toilets anywhere, but 0:01:12.800 --> 0:01:15.840 kept a portable toilet and chopsticks for looking for gravid 0:01:15.880 --> 0:01:19.720 proglottids and collected them all every day for three hundred 0:01:19.959 --> 0:02:05.960 seventy one days. 0:02:07.000 --> 0:02:09.800 I love this first hand account. 0:02:10.080 --> 0:02:10.760 I love it. 0:02:10.919 --> 0:02:13.960 I love it so much erin it's okay, let me 0:02:14.000 --> 0:02:17.520 tell you where it's from, because I stumbled across this 0:02:17.840 --> 0:02:20.520 and it just proved to be so much deeper that 0:02:20.600 --> 0:02:24.760 I that I had expected. Okay, so that is from 0:02:25.000 --> 0:02:28.880 ETO at All twenty twenty. The paper is titled Kozen 0:02:28.960 --> 0:02:33.880 Yoshino's Experimental Infections with Tenia Solium Tapeworms an experiment never 0:02:33.960 --> 0:02:39.160 to be repeated. And this paper goes into this experiment 0:02:39.440 --> 0:02:42.720 that Yoshino did back in the nineteen thirties I believe, 0:02:42.800 --> 0:02:47.760 or late nineteen twenties, with this experimental infection of tapeworm 0:02:47.919 --> 0:02:52.160 and then the resulting papers that Yoshino published on the subject. 0:02:52.240 --> 0:02:56.480 And it's a really interesting paper. But yeah, I just 0:02:56.600 --> 0:03:00.320 I loved that description of like this, well, to do 0:03:00.360 --> 0:03:03.320 this and even if I die, the data will be useful, 0:03:03.480 --> 0:03:04.000 like right. 0:03:05.080 --> 0:03:07.799 The description of feeling like a little power and then 0:03:07.919 --> 0:03:10.240 just like doing it, I love that. 0:03:10.560 --> 0:03:16.720 Yeah. Yeah, ah well, Hi, I'm Aaron Welsh and I'm 0:03:16.840 --> 0:03:20.600 Erin Almann Updike and this is this podcast will Kill You. 0:03:21.000 --> 0:03:23.760 And today we're talking about tapeworms. 0:03:23.800 --> 0:03:24.640 Tapeworms. 0:03:24.800 --> 0:03:27.480 Yeah, yeah, it's gonna be fun to see how this 0:03:27.520 --> 0:03:29.919 one shakes out. Erin, I have no idea what you're 0:03:29.960 --> 0:03:30.720 going to talk about. 0:03:31.160 --> 0:03:34.960 I know nothing about how tapeworm biology works, and so 0:03:35.640 --> 0:03:38.800 it's gonna be interesting. But I'm excited for it. 0:03:38.800 --> 0:03:39.840 It's gonna be fun. 0:03:40.160 --> 0:03:42.880 And I'm also excited because guess what time it is. 0:03:43.200 --> 0:03:45.800 It's quarantine any time it is. 0:03:46.480 --> 0:03:48.000 What are we drinking this week? 0:03:48.200 --> 0:03:50.440 We're drinking Brave New Worm. 0:03:52.920 --> 0:03:56.600 I feel like in one of our Wormy Parasite episodes 0:03:56.640 --> 0:03:59.240 we talked about how we're just gonna do like worm 0:03:59.480 --> 0:04:03.160 worm pun worm world puns. Yes, Lydia point on And 0:04:04.000 --> 0:04:06.920 I actually really like the name for this, and I 0:04:06.920 --> 0:04:11.840 think it fits tapeworms because Tenia tapeworms the ones that 0:04:11.920 --> 0:04:17.479 infect humans part of their host switching abilities and being 0:04:17.480 --> 0:04:19.640 able to find a new host. I feel like it's 0:04:19.760 --> 0:04:23.640 encapsulated in the name Brave New Worm. I love it. 0:04:23.760 --> 0:04:25.400 I love it. How poetic Karin. 0:04:25.320 --> 0:04:30.719 Yeah, and in Brave newworm is gin lemon juice, Earl 0:04:30.760 --> 0:04:33.719 Gray tea, a little bit of honey, simple syrup, and 0:04:33.760 --> 0:04:37.799 then garnish with a piece of lemon that you cut 0:04:37.880 --> 0:04:38.560 in the shape of. 0:04:38.560 --> 0:04:43.960 A worm, like a really long tapeworm. Preferentially, Yeah, we'll 0:04:43.960 --> 0:04:47.240 show pictures and we'll post the full recipe for that 0:04:47.320 --> 0:04:50.599 quarantini as well as our non alcoholic plusy Brita on 0:04:50.640 --> 0:04:52.800 our website This podcast will kill You dot com and 0:04:53.000 --> 0:04:55.240 all of our social media channels. 0:04:54.839 --> 0:04:57.760 And on our website This podcast will kill You dot Com. 0:04:57.800 --> 0:05:00.960 I've got my post it note here, which will tell 0:05:01.000 --> 0:05:05.560 me that you can find the sources for this episode 0:05:05.600 --> 0:05:10.520 and all of our episodes transcripts, recipes, bookshop dot Org, 0:05:10.600 --> 0:05:16.320 affiliate account, Goodreads list, music by Bloodmobile, merchandise, Patreon, and 0:05:16.440 --> 0:05:17.720 alcohol free episodes. 0:05:18.360 --> 0:05:21.080 I want everyone to know that Aaron was genuinely looking 0:05:21.160 --> 0:05:22.760 at a little post it note in her eyes kept 0:05:22.760 --> 0:05:25.400 flicking back and forth to read the post it note, 0:05:25.480 --> 0:05:26.720 and I really enjoyed it. 0:05:26.960 --> 0:05:29.320 You know what, There's only so much I can fit 0:05:29.400 --> 0:05:32.599 into my brain, unlike a given evening that we're recording, 0:05:32.760 --> 0:05:34.800 and post it's really helped me. 0:05:37.960 --> 0:05:41.720 Speaking of post its, shall we refer to our notes. 0:05:41.960 --> 0:05:44.240 And great segue. Thanks. 0:05:44.279 --> 0:05:48.800 Thanks, I try and dive into this episode. 0:05:49.040 --> 0:05:50.920 Let's do it. I'm excited right. 0:05:50.760 --> 0:06:27.600 After this break. There are quite a few different species 0:06:27.640 --> 0:06:31.680 of tapeworm. As a general rule, there's a lot, but 0:06:31.800 --> 0:06:35.240 there are a few different species that can infect humans. 0:06:36.240 --> 0:06:38.320 Those are which we're going to be focusing on today. 0:06:39.520 --> 0:06:44.280 Some of these species infect humans because we are evolutionarily 0:06:44.720 --> 0:06:50.440 the definitive or final host for adult worms, and some 0:06:50.520 --> 0:06:55.039 of which infect us incidentally, either as adult worms or 0:06:55.279 --> 0:06:58.000 as the intermediate stages, which I'll get into in just 0:06:58.040 --> 0:07:02.880 a minute. Plan for this biology section, we'll see how 0:07:02.920 --> 0:07:07.000 this turns out, was to just talk very generally about 0:07:07.040 --> 0:07:10.800 tapeworms as a group, because I think the broad strokes 0:07:10.800 --> 0:07:14.680 of their life cycles are not only so fascinating, but 0:07:14.720 --> 0:07:17.040 we can also cover a lot of ground by keeping 0:07:17.040 --> 0:07:20.040 things pretty general. And then I'll focus on a couple 0:07:20.080 --> 0:07:23.960 of species of tapeworm in particular that for humans stand 0:07:24.040 --> 0:07:24.800 a little bit apart. 0:07:25.400 --> 0:07:26.680 That makes sense, Let's do it. 0:07:27.280 --> 0:07:35.240 So tapeworms are fascinating, almost adorable little creatures. Sure, some 0:07:35.280 --> 0:07:39.760 of the scanning electron micrographs are like kind of cute, Okay, 0:07:40.520 --> 0:07:44.880 Tapeworms are flatworms in the phylum platy Helmentes in the 0:07:44.960 --> 0:07:49.360 class Cestoda, so different than the other flatworm friends that 0:07:49.360 --> 0:07:52.320 we've talked about on this podcast, the flukes which are 0:07:52.360 --> 0:07:57.080 the causative agent of schistosimiasis, and tapeworms are an entirely 0:07:57.200 --> 0:08:00.960 parasitic class of animals, which is awesome in and of itself, 0:08:01.520 --> 0:08:05.120 and in general they have fairly complex life cycles, much 0:08:05.320 --> 0:08:09.040 like the flukes that cause schistosimiasis. So let's go over 0:08:09.080 --> 0:08:13.080 it first. We'll start with the eggs, which are passed 0:08:13.160 --> 0:08:17.560 in feces, so in poop, the eggs enter the environment 0:08:18.200 --> 0:08:23.640 and then have to first be ingested by an intermediate host. Now, 0:08:23.800 --> 0:08:28.280 this intermediate host can be anything from a copapod in 0:08:28.320 --> 0:08:31.560 the case of something like a fish tapeworm, to a 0:08:31.680 --> 0:08:35.040 pig or a cow in the case of various species 0:08:35.040 --> 0:08:39.000 of human tapeworms, or a sheep or a rat in 0:08:39.040 --> 0:08:42.199 the case of like a dog tapeworm, et cetera, et cetera. Right, 0:08:43.559 --> 0:08:48.199 and in these intermediate hosts, in general, the eggs leave 0:08:48.840 --> 0:08:53.120 the guts of those animals and mature into a larval 0:08:53.240 --> 0:08:57.320 or immature stage which insists, so they tend to form 0:08:57.400 --> 0:09:01.040 these little cysts in various organs in the body, like 0:09:01.160 --> 0:09:05.520 the liver or the muscle or whatever, and then they 0:09:05.640 --> 0:09:09.520 hang out in these intermediate hosts, often not causing too 0:09:09.600 --> 0:09:14.080 much harm, although sometimes they might hasten capture by a 0:09:14.120 --> 0:09:17.920 carnivore in some way, like maybe making a rat easier 0:09:17.960 --> 0:09:22.160 to catch by a dog, for example. And then these 0:09:22.200 --> 0:09:25.640 cyst stages have to be ingested by their final or 0:09:25.640 --> 0:09:30.840 definitive host, and once they are they exist in the 0:09:30.880 --> 0:09:36.160 guts of that definitive host. They mature in vertebrate guts 0:09:36.200 --> 0:09:39.200 into adult tapeworms. Gennero. 0:09:39.880 --> 0:09:43.440 So can we talk a little bit about the cyst sure? 0:09:43.640 --> 0:09:45.000 What would you like to talk about? 0:09:45.040 --> 0:09:47.040 What is it made of? 0:09:47.080 --> 0:09:47.200 Like? 0:09:48.000 --> 0:09:51.320 Is the growth of the tapeworm just completely arrested? Like? 0:09:51.840 --> 0:09:56.000 Is it? Great question? It depends on the species, but 0:09:56.120 --> 0:10:00.920 in general no. So the cysts are little little baby tapeworms. 0:10:01.520 --> 0:10:03.839 They have a little head and a little skull x 0:10:04.280 --> 0:10:06.000 that's what the head is called. I'll talk about it 0:10:06.000 --> 0:10:09.000 in a second. And then they have like a part 0:10:09.080 --> 0:10:11.560 of a little body, and then they have just a 0:10:11.600 --> 0:10:15.920 little structure around them, which is what entraps itself in 0:10:16.000 --> 0:10:19.800 say the muscle or the liver of the intermediate host, 0:10:20.240 --> 0:10:20.600 and it. 0:10:20.520 --> 0:10:24.200 Does that to evade the immune system exactly. 0:10:24.360 --> 0:10:27.360 So these cysts tend to be very good at evading, 0:10:27.960 --> 0:10:32.200 especially vertebrate hosts immune responses. They just can hang out 0:10:32.200 --> 0:10:35.040 there for in some cases quite some time, like a 0:10:35.080 --> 0:10:38.760 number of months or even years, just waiting to be ingested. 0:10:39.920 --> 0:10:42.920 And then another question about these cysts, I just I'm 0:10:43.000 --> 0:10:46.240 so fascinated by yeah, by these cysts. So if the 0:10:46.280 --> 0:10:50.760 intermediate host dies with this, with these cysts, you know, 0:10:50.840 --> 0:10:56.440 throughout their muscle, how long in the environment would they last? 0:10:56.559 --> 0:10:59.240 Would there be scavengers that could come in? Like, how 0:10:59.320 --> 0:11:00.120 would that work? 0:11:00.440 --> 0:11:03.560 That is a very good question. I don't fully know 0:11:03.600 --> 0:11:06.040 the answer, and I expect that it varies quite a 0:11:06.040 --> 0:11:09.800 lot depending on the species. But in general, this is 0:11:09.800 --> 0:11:13.720 something that usually needs to be ingested while it's alive, 0:11:14.200 --> 0:11:18.000 So it would be a lot of times it's carnivores 0:11:18.040 --> 0:11:20.640 that are the kind of definitive host of these creatures, 0:11:21.160 --> 0:11:25.240 or in the case of like fish tapeworms, if fish 0:11:25.280 --> 0:11:27.480 are ingesting copa pods and things whole. 0:11:28.040 --> 0:11:29.880 Right, Okay, yeah. 0:11:30.200 --> 0:11:32.080 I want to talk for a little bit about the 0:11:32.120 --> 0:11:39.160 adult tapeworms. Because they're fascinating. So tapeworms will post a 0:11:39.160 --> 0:11:41.120 lot of pictures of them on our Instagram, So if 0:11:41.160 --> 0:11:45.079 you don't follow us, you should, because again they're very cool. 0:11:45.559 --> 0:11:50.360 They have a head which has no eyes, no light 0:11:50.400 --> 0:11:56.559 sensing organs, no mouth. Their head is often called a skulex, 0:11:57.040 --> 0:12:00.679 and it's just a set of hooks and or suckers 0:12:01.400 --> 0:12:04.120 that they use to anchor on to the gut wall 0:12:04.320 --> 0:12:08.760 of their vertebrate host and then attached to this little 0:12:08.880 --> 0:12:13.680 head or skulllex. They have a skinny, little neck and 0:12:13.760 --> 0:12:19.240 from this neck they make their body, and their body 0:12:19.400 --> 0:12:23.320 is formed of a bunch of segments that are called proglottids. 0:12:24.960 --> 0:12:29.320 So this worm, what it does is it attaches by 0:12:29.360 --> 0:12:31.760 the hooks on its head to our gut wall and 0:12:31.920 --> 0:12:37.160 absorbs its nutrients through its body by just diffusion across 0:12:37.160 --> 0:12:41.600 its body. It doesn't have a mouth, what exactly, It 0:12:41.640 --> 0:12:45.280 has no mouth, just as our gut contents flow past. 0:12:45.440 --> 0:12:49.040 They absorb whatever they need through their tegument that's their 0:12:49.120 --> 0:12:54.640 version of skin, and their neck is constantly producing more 0:12:54.720 --> 0:12:57.959 and more of these proglotted segments from like you can 0:12:57.960 --> 0:12:59.679 think of it as from like the top of the 0:12:59.720 --> 0:13:04.280 neck and then they displace the older proglottids down and 0:13:04.360 --> 0:13:07.920 down and down right. And so this tail of the 0:13:07.960 --> 0:13:11.240 body of this worm is just growing longer and longer 0:13:11.240 --> 0:13:15.560 and longer, reaching toward our anus right as it grows 0:13:15.880 --> 0:13:20.800 along our gut tract, adding more and more segments. Now 0:13:20.920 --> 0:13:25.719 these proglotted segments. Each one of these segments has an 0:13:26.040 --> 0:13:31.600 entire reproductive tract, both like testes that make sperm and 0:13:31.800 --> 0:13:38.400 ovaries that are making eggs, and they self fertilize. It's amazing. 0:13:38.520 --> 0:13:40.559 That is incredible, I know. 0:13:41.000 --> 0:13:44.120 And as this worm matures and becomes longer and longer, 0:13:44.200 --> 0:13:49.040 adding these segments, the mature final segments that are fully fertilized, 0:13:49.320 --> 0:13:54.520 chalk full of eggs break off and are passed through 0:13:54.559 --> 0:13:57.959 the feces of the host and enter the environment. Chalk 0:13:58.080 --> 0:14:01.559 full of hundreds, if not thousands of eggs. 0:14:02.200 --> 0:14:06.440 Interesting, So it's not a lot of eggs in your stool, 0:14:06.640 --> 0:14:13.720 it's this whole blotted for vlotted. Yeah, oh wow, I know, 0:14:14.080 --> 0:14:18.560 it's great, right, I My mind is just blown, I know, 0:14:19.560 --> 0:14:19.880 and I. 0:14:19.840 --> 0:14:21.080 Know that that was a lot. So I'm going to 0:14:21.200 --> 0:14:23.600 just do a very brief recap of the whole life 0:14:23.600 --> 0:14:28.960 cycle of tapeworms. Ready, yeah, egg intermediate host eats the 0:14:29.000 --> 0:14:34.680 egg cysts in various tissues. Definitive host eats those tissues. 0:14:35.280 --> 0:14:39.240 Adult worm in the gut poops out eggs. That's all 0:14:39.400 --> 0:14:40.480 tapeworms in general. 0:14:40.640 --> 0:14:44.480 A circle of life, circle of life. Okay, so this 0:14:44.600 --> 0:14:48.800 probably varies a lot from species to species. But how 0:14:48.840 --> 0:14:52.840 long do some of these eggs stay in the environment 0:14:52.920 --> 0:14:54.880 or can exist in the environment. 0:14:54.680 --> 0:14:57.640 Great question. I don't have an exact number, but they 0:14:57.680 --> 0:15:01.480 are quite environmentally tolerant in gener so they can like 0:15:01.600 --> 0:15:04.680 dry out and still be potentially infectious, so they can 0:15:04.800 --> 0:15:11.360 live for a decent amount of time. Wow. Yeah, Now 0:15:11.920 --> 0:15:16.280 many tapeworm species really. I think some of the papers 0:15:16.280 --> 0:15:19.560 I read said that probably every vertebrate has at least 0:15:19.600 --> 0:15:22.800 one species of tapeworm that infects it. So there are 0:15:23.160 --> 0:15:25.680 tons and tons of tapeworm species, and that was a 0:15:25.800 --> 0:15:29.400 very general overview. We're going to focus today on just 0:15:29.440 --> 0:15:35.120 a few of these tapeworm species that infect humans. Tenia solium, 0:15:35.520 --> 0:15:40.040 Tenia saginata, and Tenia asiatica, which is very closely related 0:15:40.040 --> 0:15:44.960 to Tenia saganata. These three are the main species of 0:15:45.000 --> 0:15:51.480 tapeworm that have humans us as a major definitive host. 0:15:51.840 --> 0:15:55.360 Tenius saganata is commonly known as the beef tapeworm because 0:15:55.360 --> 0:15:58.120 its intermediate host is a cow and we get infected 0:15:58.120 --> 0:16:02.600 from undercooked cow meat. Tenius solium is commonly known as 0:16:02.600 --> 0:16:05.600 the pork tapeworm because its intermediate host is a pig 0:16:05.920 --> 0:16:09.520 and we get it from eating undercooked pork. Teenie asiatica 0:16:09.560 --> 0:16:14.240 also tends to infect pigs. Now, there are a few 0:16:14.280 --> 0:16:16.880 other species that are very important for humans as well, 0:16:17.360 --> 0:16:21.600 like Diphilobothrium latam at all. There are so many different 0:16:21.600 --> 0:16:26.920 species of Diphilobothrium. These are the fish tapeworm. These also 0:16:27.160 --> 0:16:30.120 can use humans as a definitive host, but they're not 0:16:30.400 --> 0:16:33.240 very species specific, so they can grow to adulthood in 0:16:33.360 --> 0:16:35.320 various other mammals and birds as well. 0:16:35.760 --> 0:16:39.080 Okay, question about that one. Actually, yeah, so you said 0:16:39.120 --> 0:16:42.000 that in that genus that I'm not going to attempt 0:16:42.080 --> 0:16:47.040 to say die Philobothrium. You're doing great, thanks, But the 0:16:47.080 --> 0:16:51.520 fish tapeworms fish are the definitive hosts, and copopods are 0:16:51.520 --> 0:16:52.680 often the intermediate hosts. 0:16:52.840 --> 0:16:57.480 Great question. They often have two intermediate hosts ahah have 0:16:57.520 --> 0:17:01.040 an even more complex life cycle, first little copapods and 0:17:01.160 --> 0:17:05.080 then fish, and then either a bigger fish, or mammals 0:17:05.160 --> 0:17:07.199 or birds a lot of times mammals or birds. 0:17:07.440 --> 0:17:09.240 Cool cool, got it, Yeah, great. 0:17:09.080 --> 0:17:13.320 Questionnairein so, let's talk about the symptoms when you get 0:17:13.359 --> 0:17:19.000 infected with an adult tapeworm. The thing about for humans, 0:17:19.080 --> 0:17:22.560 at least almost all these species of tapeworm, whichever of 0:17:22.640 --> 0:17:26.560 those four major groups we're talking about, is that these 0:17:26.640 --> 0:17:30.240 species that are well adapted to humans, when they infect 0:17:30.320 --> 0:17:33.399 us the way that they're supposed to as adult tapeworms 0:17:33.480 --> 0:17:36.480 in our guts, they really don't do all that much 0:17:37.280 --> 0:17:40.439 to us. That is, they absorb some of our food. 0:17:40.880 --> 0:17:46.680 They can cause abdominal pain, maybe some cramping, some diarrhea. 0:17:46.840 --> 0:17:50.080 If the worm burden got to be really high, then 0:17:50.119 --> 0:17:53.360 they could potentially cause a bit more of a symptomatic infection, 0:17:54.080 --> 0:17:57.040 but it still isn't even on the scale of say 0:17:57.119 --> 0:18:00.800 something like hookworm that we've covered in the past, because 0:18:00.960 --> 0:18:04.800 they're not burrowing into our gut wall. They're just hanging 0:18:04.840 --> 0:18:08.159 on right, and they're not sucking our blood. They're just 0:18:08.320 --> 0:18:11.000 borrowing some of our food as it passes through our 0:18:11.040 --> 0:18:14.440 small intestine before we get a chance to absorb it. Okay, 0:18:15.119 --> 0:18:18.960 Fish tapeworms have been associated with some anemia due to 0:18:19.040 --> 0:18:23.760 pour vitamin B twelve absorption because these worms attach in 0:18:23.800 --> 0:18:28.600 our small intestine and that's where we absorb vitamin B twelve. Interesting, Yeah, 0:18:28.640 --> 0:18:32.520 but even that is fairly rare, okay, And I couldn't 0:18:32.520 --> 0:18:35.840 find very great data on this, but I don't think 0:18:35.960 --> 0:18:39.359 in general, worm burdens with tapeworm tend to be quite 0:18:39.440 --> 0:18:43.359 as high as they can get with like hookworm anyways. 0:18:44.880 --> 0:18:48.520 But the point is that, in a similar way that 0:18:48.560 --> 0:18:53.640 we actually saw with schistosimiasis, the severity of tapeworm infection 0:18:54.520 --> 0:18:57.720 comes not when tapeworms are acting the way that they're 0:18:57.760 --> 0:19:01.440 supposed to, but it's when they start acting a way 0:19:01.520 --> 0:19:05.280 that they're not supposed to. That is when we as 0:19:05.359 --> 0:19:09.280 humans get infected with the wrong life stage of the tapeworm. 0:19:10.240 --> 0:19:13.760 So when instead of being the definitive host, we become 0:19:13.880 --> 0:19:18.080 the intermediate host, that is when problems arise. And it 0:19:18.160 --> 0:19:20.800 turns out that this can happen with a few different 0:19:20.840 --> 0:19:25.560 species of tapeworm huh. The pork tapeworm which I've already mentioned, 0:19:25.600 --> 0:19:31.000 Tenea solium, and two species of dog or canine tapeworm, 0:19:31.160 --> 0:19:37.520 A Chinococcus granulosis and A Chinococcus multilocularis interesting. Yeah, it 0:19:37.600 --> 0:19:41.800 gets so much more interesting. So first, let's talk about 0:19:41.840 --> 0:19:47.240 how this actually happens. So, humans get infected with adult 0:19:47.280 --> 0:19:52.199 tapeworms by eating undercooked meat of beef or pork or 0:19:52.280 --> 0:19:57.200 fish that is filled with cysts. Right, So if instead 0:19:57.320 --> 0:20:00.520 of eating undercooked meat that has cysts in it and 0:20:00.560 --> 0:20:04.280 getting infected with an adult tapeworm, if we instead come 0:20:04.320 --> 0:20:08.040 into contact with the eggs of these tapeworms, that is, 0:20:08.080 --> 0:20:12.679 if we ingest anything contaminated with human poop or with 0:20:12.920 --> 0:20:17.720 dog poop, then we become the sheep or the pigs, 0:20:18.320 --> 0:20:21.520 and instead of an adult tapeworm in our gut, these 0:20:21.600 --> 0:20:26.320 eggs hatch in our stomach, become those adorable little embryos 0:20:26.520 --> 0:20:31.000 and invade through our gut walls, travel through our bloodstream 0:20:31.080 --> 0:20:34.320 to our tissues, and insist themselves with the hope of 0:20:34.400 --> 0:20:35.600 eventually being eaten. 0:20:36.440 --> 0:20:40.040 Does it ever happen where if you have an adult 0:20:40.080 --> 0:20:43.960 tapeworm infection and they're making those eggs, and they're making 0:20:44.040 --> 0:20:47.480 that little eggsac thing that that breaks open and you 0:20:47.560 --> 0:20:49.000 get insistement that way. 0:20:49.640 --> 0:20:51.520 Oh do you mean auto infection? 0:20:51.880 --> 0:20:55.879 Oh what a great question. 0:20:56.560 --> 0:21:00.520 Yes, it absolutely can happen. Okay, that kind of is 0:21:00.600 --> 0:21:03.159 what in that first hand account when the author ate 0:21:03.280 --> 0:21:07.440 SISTA SIRTC guy, that is the intermediate stage. So they 0:21:07.720 --> 0:21:12.000 ate the intermediate stage in order to grow the adult tapeworm. 0:21:12.280 --> 0:21:15.960 But what they were worried about is accidentally becoming exposed 0:21:16.000 --> 0:21:17.679 to the eggs that they were pooping out. 0:21:18.040 --> 0:21:22.080 Right, right, And so when someone has these cysts in 0:21:22.119 --> 0:21:25.359 their tissues, is it more likely that they got it 0:21:25.400 --> 0:21:29.439 from ingesting eggs from another source or from this auto infection? 0:21:30.040 --> 0:21:34.159 Great question, I think in general, from any other source. 0:21:34.800 --> 0:21:37.000 One of the papers that I read said that about 0:21:37.040 --> 0:21:41.480 twenty five percent of people with neurocysta circosis, which I'll 0:21:41.480 --> 0:21:44.120 talk about that in a second, but basically with these 0:21:44.160 --> 0:21:49.520 cysts either had in the past or currently had a tapeworm. Okay, 0:21:49.640 --> 0:21:53.199 so that's a fairly low percentage, But that was just 0:21:53.280 --> 0:21:55.600 one paper. I think we don't have a great handle 0:21:55.640 --> 0:22:00.240 on how much auto infection happens. Okay, so we talk 0:22:00.240 --> 0:22:04.560 about why these cysts become a problem, and you probably 0:22:04.560 --> 0:22:09.160 already know why. It's because they can insist almost anywhere. 0:22:10.160 --> 0:22:14.840 So in the case of Tinia solium, the disease that 0:22:14.920 --> 0:22:18.080 results from infection with this immature life stage is called 0:22:18.280 --> 0:22:22.960 cistus orcosis, and the symptoms of cistus orcosis can really 0:22:23.080 --> 0:22:27.159 vary because these embryos are traveling via our bloodstream and 0:22:27.240 --> 0:22:30.640 just they're finding their way anywhere that our blood vessels go, 0:22:31.160 --> 0:22:35.080 which is really anywhere. And you can find them insisted 0:22:35.160 --> 0:22:38.760 in muscle tissue, where most of the time they're asymptomatic. 0:22:39.840 --> 0:22:43.440 You can also find them in subcutaneous tissue like underneath 0:22:43.440 --> 0:22:46.840 the skin. Which what's really interesting is that this tends 0:22:46.840 --> 0:22:50.520 to only happen from infections happening in Asia rather than 0:22:50.560 --> 0:22:54.399 in Latin America or Africa, and at least from what 0:22:54.440 --> 0:22:57.160 I can tell, this likely has to do with the 0:22:57.200 --> 0:23:00.440 genetic differences in the population of Tinia solium in these 0:23:00.440 --> 0:23:04.080 different areas rather than any human susceptibilities. 0:23:04.400 --> 0:23:07.680 Okay, quick question, how big are the cysts? 0:23:08.040 --> 0:23:12.400 Great question? Usually for tenius olium one to two centimeters 0:23:12.480 --> 0:23:12.760 or so. 0:23:13.080 --> 0:23:14.400 Oh that's still bigger than I thought. 0:23:14.640 --> 0:23:20.840 Yeah, not huge. Just wait, and these cysts tend to 0:23:20.880 --> 0:23:25.560 be present for just a few months to years, but 0:23:25.680 --> 0:23:30.879 eventually they do gradually disappear as the embryo dies, and 0:23:30.920 --> 0:23:33.520 then our body recognizes it and kind of just takes 0:23:33.560 --> 0:23:34.920 care of that cyst. 0:23:35.240 --> 0:23:38.000 It's just tired of waiting around for you to be 0:23:38.400 --> 0:23:39.240 eaten by a. 0:23:39.200 --> 0:23:41.360 Predator, right, it just can't hack it anymore. 0:23:41.800 --> 0:23:44.000 And how long do adult tape worms live? 0:23:44.240 --> 0:23:47.560 Oh, it really varies. Let me go back to where 0:23:47.560 --> 0:23:52.840 I had that, Deah. Some parasitology textbooks will tell you 0:23:52.880 --> 0:23:57.520 like twenty to twenty five years. Oh, but I don't 0:23:57.520 --> 0:24:00.200 think that that's it's thought that that's probably an over 0:24:00.440 --> 0:24:03.440 estimation from like anecdotal cases from a long time ago. 0:24:03.720 --> 0:24:06.280 So it's probably less than five years. But it's still 0:24:06.320 --> 0:24:09.000 like they're with you for a chunk of your life, right. 0:24:09.320 --> 0:24:10.439 Yeah. 0:24:10.680 --> 0:24:14.240 These cysts from tineas solium can also end up in 0:24:14.320 --> 0:24:17.240 the eye, where in the eye you can imagine they 0:24:17.280 --> 0:24:20.000 can actually cause quite a bit of damage, like causing 0:24:20.080 --> 0:24:26.000 visual impairment because they're blocking vessels, et cetera. But the 0:24:26.040 --> 0:24:30.800 most common and most detrimental place where this particular parasite 0:24:30.960 --> 0:24:34.800 tends to insist is in the brain, right. And when 0:24:34.840 --> 0:24:39.119 it insists in the brain, it's called neurocystus orcosis brain 0:24:39.480 --> 0:24:43.000 sisters orcosis, And what happens in the brain is very 0:24:43.080 --> 0:24:47.480 similar to what happens anywhere else. These embryos make their home, 0:24:48.760 --> 0:24:52.200 they form these one to two centimeter cysts. They usually 0:24:52.240 --> 0:24:55.600 don't get much bigger than that, although they can. They 0:24:55.680 --> 0:24:58.160 hang out there for a number of months or years, 0:24:58.359 --> 0:25:02.760 and then eventually they degener our immune system wakes up 0:25:02.800 --> 0:25:05.679 and kind of notices these cysts for the first time 0:25:06.320 --> 0:25:13.480 and in helping with that degeneration causes inflammation. So neurosystus 0:25:13.520 --> 0:25:17.080 orcosis can end up causing, as you might imagine, any 0:25:17.280 --> 0:25:21.560 range of symptoms in your brain, depending on how many 0:25:21.680 --> 0:25:26.160 cysts you have, because if you're exposed to tapeworms, remember 0:25:26.200 --> 0:25:30.520 these proglottids are filled with hundreds, if not thousands of eggs, 0:25:31.400 --> 0:25:34.639 so you could potentially be exposed to quite a large number. 0:25:36.720 --> 0:25:40.359 It also depends on if these cysts are growing, because 0:25:40.400 --> 0:25:42.359 sometimes they do get a bit larger than one to 0:25:42.400 --> 0:25:44.639 two centimeters, and if they happen to be in the 0:25:44.640 --> 0:25:48.760 wrong part of the brain, that can cause blockage of 0:25:49.080 --> 0:25:52.119 the cerebrospinal fluid flowing in the brain, which can increase 0:25:52.160 --> 0:25:56.240 the pressure in your brain. But more commonly it's the 0:25:56.359 --> 0:25:59.920 end stages this inflammation, as our body is actually try 0:26:00.000 --> 0:26:05.000 trying to get rid of this cyst that causes symptoms 0:26:05.280 --> 0:26:13.680 like headaches, like mental status changes, or like very commonly epilepsy. Right, 0:26:14.480 --> 0:26:17.080 And it turns out that neurosys to circosis is one 0:26:17.119 --> 0:26:20.480 of the most common, if not the most common cause 0:26:20.560 --> 0:26:23.280 of infectious epilepsy in a lot of parts of the world, 0:26:24.280 --> 0:26:27.520 which I totally didn't realize until doing this episode. 0:26:27.760 --> 0:26:35.400 Yeah, can we talk worm burden or cyst burden. Do 0:26:35.440 --> 0:26:40.200 you have numbers for like the median cyst burden in 0:26:40.320 --> 0:26:45.040 someone who has, you know, neurosyst sircosis, or at what 0:26:45.160 --> 0:26:48.760 is there a threshold at which point epilepsy is common 0:26:48.920 --> 0:26:50.919