July third.
I woke that morning lethargic. The coffee didn't help my energy materialize, nor did it help clear away the clouds that had formed in my brain. My functionability was so affected that at one point I was sitting at my desk holding my head in my hands. That was the moment home seemed like the best place for me to be. Something was wrong, something was churning. That was the night the sickness hit. It reared its ugly head first by the expulsion of the contents of my stomach. I couldn't
stop it from happening. Try as I may, no deep breath would stay the sick I was thwarted at every turn. Worship at the throne of the toilet God was inevitable. Dehydration became the scariest factor in this situation. I was losing more water than I could drink, partly because I had no desire to drink. I tried to work, I tried to eat. I slept on my sofa, I slept
in my bed. I didn't get dressed. I barely ate, sitting my apartment alone, feeling the rumblings of my bowels, knowing that I was getting neither enough water nor nutrients was alarming. July eighth, Tuesday, a week since the beginning niagara, rushed again. All the happiness and confidence that had been present on Monday got flushed right down the toilet. I was scared, but I thought I just had to keep waiting.
July twenty fourth, I sent an email to my doctor's office pleading my case, begging for a spot in his busy schedule.
Three weeks after life.
Took a drastic turn towards Liquidville, I had an appointment July twenty sixth Thursday. How was I going to catch the evacuating contents of my colon bowl bag? Milk joke, milk joke with the top cut off ew.
A bag it was.
Having finally figured out how to catch the liquid, I was ready now to the fun part. I was back on my knees at the throne. Only this time I was armed with a spoon small, taller than one.
Used to feed a child. It's baby food.
Thankfully, I only had to scoop about a quarter inch worth of waiste into each vial with a spoon that small, though it took scoop after scoop after scoop. July twenty ninth Sunday, I got a call from another doctor who works with my doctor. I'd been compromised. Small amounts of the parasite Girardia had been found a parasite. I had a parasite. After the initial shock, relief again washed over me.
It was treatable with an antibiotic and I could actually start it that day, August fifth, Sunday morning, I took the final dose of antibiotic. The party is over. Girardia has left the building. As the host of a few human parties in my time, this was one of my least favorite. A host should have fun at their own party, but this party was full of selfish guests. They took and took and took from me, giving me nothing in
return for my accommodations. That's a very you find the best first hand accounts, Aaron.
That one is one of my favorites. I think it's amazing. Hi, I'm Aaron Welsh.
And I'm Erin Almond Updike and.
This is this podcast will kill you?
And where did that first hand account come from?
Aaron?
So that came from a blog I found. It's Michael Roarer dot blogspot dot com, and it's from a August twenty twelve entry titled Giardia Ruined My gily Idea, which is an amazing title.
It's a very good title.
So, as you might have guessed, this week we are covering Giardia. Yes, we are the beautiful, beautiful protozoan parasite that will cause you to have horrible diarrhea.
Yes, how fun, wonderful? What enjoy?
This is kind of back to our standards in terms of disease, which I feel like we haven't done for a while. So I'm excited to like it's a it's a pathogen, and it makes you sick, like our first season ones. You know, I feel like we've been doing some off the wall crazy episodes lately.
We did h Pylori, which was along the same lines.
That's true. Yeah, no, it's hard to keep track.
We have done a lot of sort of non traditional format type ones.
I'm very excited for this.
I'm excited to hear all about how it works. I don't really know how it works.
Oh good, I can't wait to tell you.
To honor Giardia. What are we drinking this week?
Our quarantine this week is backpackers Delight.
That's a good that's named because it is a very frequent infection in backpackers and many other people as well. But backpackers tend to get it from drinking contaminated streams, so make sure to filter your water. People. What's in backpackers delight.
In this beverage. We have coconut water, you know, to rehydrate you after all that diarrhea, perf pineapple juice because it's tasty with coconut water, Ginger liqueur because that's good for your stomach, right fans, and vodka.
Not good for your stomach, not good to rehydrate you, but essential for our quarantini. Yes, but our Placy Burrita does not contain alcohol, and we will post the recipe to both the Quarantini and the alcohol free Plasy Brita on our website and on our social media platforms.
Yes we will.
So before we start on today's episode, I actually have two corrections that I'd like to make that people emailed us about so very quickly. One is from I believe our last episode or second to last episode on encephalitis, so in that this is very embarrassing. Aaron, you mentioned that Robert de Niro like won the Academy Award, and I was like, oh, I'll fact check you. And I did that live during our recording of the episode, and I failed at fact checking you.
I did it incorrectly. Robert de Niro did not win.
Academy Award for Best Actor for Awakenings, but he was dominated he was nominated. Thank you to True Trivia Nerd Amelia for writing to.
Let us know.
Thanks Amelia, Yeah, keep on the path.
Oscar Trivia Nerd self proclaimed.
Okay.
The other one is from our recent crossover with Indefensive Plants where we talked about aspirin. So as I was talking about all the various effects of aspirin, one of the effects of aspirin is that it's an antipyritic or an anti fever, so it reduces fever. Yeah, And in the episode I mentioned that this is due to its effects on vasodilation.
I got over excited.
Vasodilation can produce like local heat production, so like if you get a cut and then you have heat, the cut feels hot. That kind of heat production can be from the vasodilation. But systemically, aspirin is even cooler in that prostaglandins in your brain, which aspirin blocks the production of modulate the temperature center in your brain. So aspirin and other end sets actually work by reducing the temperature set point in your brain or blocking the increase in it,
and that's how they reduce fever. So that's actually a much cooler mechanism, and I'm really bummed that I didn't mention it in that episode. So thank you very much to Kelly for emailing about this.
Interesting.
For anyone listening who has no idea what I'm talking about, that means you didn't listen to our ASPERN episodes, so you.
Should go check it out. Hey, Okay, is that all the business that we have?
Yeah?
I think so.
Well, then let's take a quick break and then get started on the biology.
Let's do it. Girardia Okay. First of all, there are there's only one R in giardia.
I know, I always call it girardia, butler giardia. Is that better?
Yeah? It's like it's like I think it's the biology equivalent of saying nuclear.
Okay, but I am always afraid that I'm gonna do that, so I never say that word in public. Let's say it, no girardia, okay, Beaver fever. That's what we're talking about today. So gr diasis, which is the disease caused by Girardia. Still doing it, Girardia giardia.
There we go. Listen, it's fine.
Giardiasis is the most frequently diagnosed intestinal parasite in the United States. That's my first fact for you. It's a massive, massive disease worldwide. It's common among travelers, it's common across the globe. So let's talk about what it is. Yeah, first of all, it's a parasite. It's a protozoan, which means it's a single celled organism. Protozoin is not a great word, but I used it.
So there.
It has three different names, three different species names that people call it, and it's all the same species, which is just to me the most annoying thing.
Oh my gosh. It made it very difficult to research.
Yeah.
It has also changed throughout history multiple times.
Oh, I'm not surprised about that at all.
Yeah.
So in medicine, they're more likely to call it Girardia lamblia. Yeah, but in the rest of everything other than like human medicine, it's Girardia duodenalis or Girardia intestinalis, which is kind of funny because duodenum is just the first part of your intestine, so it's kind of like those are interchangeable. But anyways, Girardia, I'm only saying one are erin.
It's never gonna stop. I can't at this point, it's too late. It's a flagelet, so that means it has flagella, which we've talked about before that they use to move.
And swim like a little tail, little tail in fact, not just one little tail. Girardia.
God, I did it again, didn't I.
Giardia has four sets of flagella, so it actually has eight that it uses to swim around, and it has two adorable little nuclei that look like eyeballs. Giardia is one of the cutest parasites of all time in my opinion.
I'm just gonna say, I think it is the cutest one we've done so far.
It is.
Yeah, I think it's one of the top cutest ones ever because it really looks just like a little person's head. Yeah, they're so cute. Okay, So, because this is a parasite, we get to talk about the life cycle as far as parasites go. Girardia has a very simple life cycle compared to a lot of parasites. It has two different life cycle forms. Inside of your intestine, it's called a trophozoite, and this is the form that looks like what I describe.
So it has two big old nuclei that look like eyes and eight floppy flagella that look like hair running off of it. So the trophozoite form can swim through your intestine stick on to your gut walls.
And then they also.
Divide by fission, so one trophozoite can actually replicate and replicate and replicate all on its own. They also then form a cyst phase, and the cyst phase is what you're most likely to poop out and what ends up
in the environment. You poop out trophozoides too, But the cysts are really important in their life cycle because the cysts are very resistant to environmental stressors, so they can survive in water like ponds and rivers and storm drains and mountain streams for weeks to months, and then when an unsuspecting animal comes by to take a drink from that beautiful mountain spring, they're going to get a big old mouthful of Girardia cysts, and then inside of your
body or the animal's body, that cyst will then split and produce two trophozoites and begin the cycle all over again.
How cool, right, It's beautiful and simple. I like it.
It's simple.
Yeah, it's simple. It's straightforward. Another thing that's very cool about the cysts is that they're resistant to a lot of the common ways that we disinfect water, including chlorination and ozone nation or whatever you call it o zonification.
But the chlorination is the chlorination that we use to treat the drinking water high enough to kill Giardia nod dude.
You have to filter it or you have.
To boil it. Oh, Girardia can live in your pool for up to like forty five minutes, not for a long time.
Huh interesting yes.
Mm hmmmmmmmm.
And when you're infected with it, you can poop out between one and ten billion with a b cysts.
Every time you.
Poop ten billion is a lot of cysts.
It's a lot of cysts. And guess how many cys it takes to get you sick.
Probably one, well, usually about at least ten.
Anyways, So that's why it's really really common to get girardia from contaminated water sources. That's one of the most common ways that we think about the transmission of giardia is from contaminated water. However, you can also get infected directly with trophozoites, which you're also pooping out at the
same time that you poop out cysts. So other places that you can get infected are places that have a little bit less hygiene, like maybe daycare centers AHA, which are one of the most common places that we see outbreaks in for example the United States. Tiny humans poop their diapers, rub their hands in it, touch their friends faces.
Everyone gets girardia.
I mean, we see a lot of gi things, parasized pathogens that yeah, filthy, filthy, tiny hum yes.
Okay, so let's talk about the symptoms. Symptoms can range from absolutely nothing entirely asymptomatic, just feeling normal, pooping out parasites without ever knowing that you're sick, to an acute illness that pretty much is self limited so you have diarrhea for a short time and then you get better, to some pretty severe chronic infections that can result in things like weight loss and malnutrition.
Question yes, what proportion are asymptomatic versus symptomatic.
That's a good question.
I haven't found an exact number on that, and in the epidemiology section we'll talk a little bit about why that's hard. But it does seem to be a pretty high proportion, and it depends on what strains of the parasite are circulating in the area, because different strains are more likely to produce asymptomatic infections than symptomatic infections.
It's a good question.
So the variability and presentation, like I said, is partially due to the virulence of the pathogen, like which one you end up getting infected with, but it also has a lot to do with your own host immune factor, so just something about you that makes you more likely to get a symptomatic infection. And then also the infectious dose. So how many of those cysts did you actually swallow? So let's talk about how it causes these symptoms, because I'm really excited about it.
Yes, me too.
So the biggest symptom that you get with grdiasis is diarrhea. You also get generalized abdominal pain, maybe distinctionion, maybe it feels big. Maybe you get nausea and vomiting. You can definitely get that from infection with GRDA getting better, but diarrhea is the number one. So it turns out that we don't know everything about how it causes these symptoms,
but we do know a few things. So first of all, Giardia does not invade your intestine wall, so unlike something like hookworm that when it gets in is going to make a hole in your intestine and like actually punch through,
Giardia doesn't do that. What it does is it has on its ventral surface, so on the opposite side of where the flagella are, it has this adhesive disk, so it uses its flagella to swim through your intestine up to the wall of your intestine, and then it uses this adhesive disk to just suction cup on to the wall of your intestine and then do what and then absorb your food essentially and just live and replicate. And they replicate by fission, so you don't need to have
multiple parasites to replicate. They just replicate the way that bacteria do. They just divide. They don't sexually reproduce.
There is some question as to whether they do sexually reproduce.
They definitely do recombination, which is cool.
Yeah, there's some really interesting articles that are like sex in the dark. Does giardia have sex in the dark or something like that.
It would be pretty dark in your intestine.
Yeah.
But so how long does an average giardia infection last if untreated?
It's hard to say because in some cases it can cause a really prolonged chronic infection. If you just have an acute infection, it'll probably resolve in a number of weeks, but some people can be infected for months and months.
Okay, So it's it's.
A very difficult thing to put like a straight number on the incubation period. So the time from when you're first infected to when you start showing symptoms is usually between one and three weeks, okay, Okay. So, once this parasite is a onto your intestine wall, they have a number of different mechanisms that again none of them are completely well understood, but these are the things that end
up resulting in you having potentially massive diarrhea. So first is that they basically induce the cells, the epithelial cells lining your intestine to start undergoing apoptosis, which is cell suicide.
That's bad news, I know.
So they don't directly kill any of your cells, but they kick somehow something that they're releasing causes those cells to start undergoing apoptosis and essentially dying. So what that is going to do is increase the permeability of that epithelial cell layer. So normally the cells of your intestine, you can imagine, are very tightly packed because you only want certain things to pass through. Right, you want to absorb nutrients but leave a lot of stuff in your intestine.
You want to absorb water, but not too much water, et cetera. Right, it's a very fine balance the whole process of digestion. So you're basically poking a bunch of holes by destroying these cells lining your intestine. On top of that, they flatten the microvilli. So microvilli are the protrusions on your intestinal wall that increase surface area to be able to absorb water and nutrients. If you flatten those, then you decrease the surface area. Then you can't absorb
that water and nutrient as well. So what that means is that in combination, when you have increased permeability and then you also have a decrease in the microvilli, you're completely messing up digestion essentially and absorption. What that means is that you're gonna end up with more stuff left in your intestine, and that's going to pull even more water out from your cells into your intestine instead of the other way. So that means that you're left with
a watery stool. And that's what diarrhea essentially is. Right, It's like your food is passing through without actually getting absorbed.
Does diarrhea have to be three times in twenty four hour period?
This is that's a very good question. No, there's no official definition on how you classify diarrhea. Usually we say three stools in three loose stools in twenty four hours is when you can start being like, oh, I have diarrhea and not just like one bad poop or something like that.
But it's not an official official definition.
Okay.
Yeah.
On top of that, there have been studies that show that girardia giardia increases the rate of transit through your intestine, so your food is moving faster, and if it's moving faster, then your body can't absorb everything that's in it. So that's another way that it can cause diarrhea and malnutrition. Because if it's moving so fast that you can't absorb what's in there, boom, dude, no good hmm.
I wonder if what you eat affects any of these things?
Oh, what a good question. That's a very fun question. There's more, Okay, on top of all of that, there's some evidence that giardia causes hyper secretion of electrolytes. So on top of not allowing your intestine to properly absorb electrolytes and other things in your intestine, it causes the secretion of electrolytes from your cells into your intestine. And wherever electrolytes go, water goes.
So now you have.
Even more water going from your body into your intestine instead of the other way around.
Definitely kicking you when you're down. It's not content to just like ringes a little bit. Is like no, completely dry, completely dry, burning some bridges there, right.
And so that's all of sort of the diarrhea based things that giardia. Giardia does, Okay, okay, pretty cool.
It's a lot and.
We don't fully understand exactly how it happens, but it's easy to see how the few things that we do know can end up leading to maldigestion, so losing nutrients, malabsorption, not being able to absorb these nutrients. So if you if you are not able to fight this parasite off, and you have it chronically, it's easy to see how this can become a pretty serious infection that leads.
To poor nutrition.
Yeah.
Now here's some things that I didn't really realize when I started researching this.
In many cases, giardia is linked.
To later development of a whole host of disease that we usually consider to be more autoimmune, like irritable bowel syndrome. Ah, there's a pretty strong association between infection with gerardia and irritable bowel syndrome.
Okay.
You also can get extra intestinal manifestations, so that means manifestations of this infection outside of your intestine, but not from the parasite because again, this parasite doesn't penetrate your intestine wall, so the parasite itself isn't traveling through your bloodstream and going anywhere else. But you can still get ocular symptoms, you can get like eye infection type symptoms. You can get joint pains, you can get skin rashes from gerardia.
Infection does it have some sort of surface protein that mimics human surface protein.
You're so so, I love it, Aaron.
I don't know if it mimics human proteins, but there is thought that because the intestinal wall permeability is increased, anigens from Gerardia are being sucked into your bloodstream and those are what's causing the extra intestinal manifestation. So it's not the parasit itself, but it's some of their surface protein that make it into your bloodstream.
How cool, that's cool, that's cool. That's horrible.
That's horrible.
I have a question about a symptom, Yes, rotten egg burps.
Yeah, I heard you mentioned that earlier, sulfur burps. M I didn't come across that as a thing in researching this, but I mean, it's totally screwing up your gut.
So yeah, I just.
Wondered what specifically would be causing the sulfur smell from that.
Yeah, that's a good question. I don't know, huh.
The good news about this parasite is that it's pretty easy to treat. Yeah, basically, just go on a course of antimicrobials, usually metronitozol or nitozoxinide. Another just there's a couple different classes of antimicrobials that we can use that are very effective so far at treating it. The problem is, reinfection is really really common, especially if the reason that you got infected in the first place was that sanitation
isn't great where you live or something like that. If you got infected while you were out backpacking, you're probably less likely to get.
Reinfected once you clear that infection.
But anyways, I'll talk a little bit more about that all in the epidumiology section. But anyways, that's the biology of GRDA.
I like it on the surface straightforward, but I think there's a little bit more interesting things going on.
Yeah, and it seems like there's very very cool research being done on figuring out exactly how this pathogen ends up causing all these different manifestations and exactly how it's affecting all the different cell layers in your intestine.
It's very cool.
We at this point don't even know exactly how it adheres. We know there's a bunch of different proteins that are interacting on that ventral disc to suction it on, but still, well.
It's surprising that it's sort of an up and coming field of research, considering that it's so widespread.
Yeah, yeah, Shall we take a quick break, and then I want you to tell me all about how we got here and where the heck this parasite came from.
Okay, I'll do. I'll try my best. Before I get started, I just want to admit that when I was researching this history, I had a bit of a tough time. And you know this because I complain to you in excess.
I wouldn't say excess.
Well, I did complain about it, yeah, which is nice to have this be something to complain about instead of many other things. But it shows that my life is pretty good. But the thing is is that there isn't a super cut and dry history of giardia in humans, which is strange to me because it is one of the most prevalent waterborne infections and causes of diarrhea around the world today and has probably held that title for centuries. Giardia doesn't have the glitz and glam of a pathogen
like cholera. It's more of a background parasite, always kind of causing a bit of trouble here and there, but rarely headline worthy of glitz.
And glam of color, and anyone.
Said that about cholera before, not until this podcast. That's why we're here. Yeah, but the history of Giardia can be condensed pretty much into a few sentences, and in most of the papers that I skimmed, that's all that it was. But that wouldn't really make for a very good podcast episode in my opinion. So I kept digging deeper. And as I dug more and more into the history of Giardia, I found that it was part of a largest story that I could tell, one about a new
way to see the world. Ooh, okay, just bear with me. I hope this is okay.
I love it already.
Giardia was first described in sixteen eighty one by the famous Anthony von Lavenhook when he was examining his diarrheal poop under a microscope of his own making. Yeah, that's the kind of guy he was. I think he would have been a fan of TP. We would have been friends, for sure.
Yeah.
Possibly. And so this isn't the first time that we've come across laven Hook during the podcast. And I remember this because every time I talk about him, I have to try to figure out how to say his name, and I end up just crossing my fingers and hoping for the best. But mostly when I've mentioned laven Hook, it's just been in passing. So this guy named laven Hook saw this thing, and then I would move on
to another part of the history. But for this episode, I really wanted to go more into this period of science and what a critical role the microscope played in the development of many different scientific fields and even more importantly, maybe or more interestingly, our perception of the world on the surface. Anthony van Lavenhook may not have been the person you would have predicted would discover and develop a
new way to see the world. He was born in sixteen thirty two in Delft in what was then the Dutch Republic. He was a cloth merchant and a bureaucrat for most of his life, and throughout a lot of his life he didn't really seem preoccupied or even that
much interested in the natural world. It was only later that he started to dabble in lens making and maps and collecting of odd specimens and having a curiosity's cabinet, which was by the way, all the rage of course, in the Dutch Republic in the mid sixteen hundreds.
The curiosity's cabinet, of course.
Yes, yes, I want a curiosity's cabinet. I'm getting there, okay. One warm August day in sixteen seventy four, Lavenhook was relaxed and maybe a tad restless. Though, now that he was retired and no longer had his thread counts to keep him occupied, he had turned his sites toward natural science pursuit, which often pulled him outside into the sun. On this particular August day, he does something extraordinary, something that would go on to revolutionize our understanding of the
world around us. He had taken some water from a lake that was a couple hours walk away, and he put it in a lens and tube mechanism that he had made himself an early microscope. Even though the lake was cleaned, or at least believed to be clean by the people who lived near the lake, the drop of lake water that he examined is teeming with life not
visible to the human eye on its own. The motion of these animal couoles and the water was so swift and so various downwards and roundabout that I confess I could not but wonder at it. He said about this lakewater, This marks the first time in history, probably that humans had gotten a glimpse of an entirely new world not visible to the naked eye. Discoveries like this don't often happen in isolation, although they're often told in that way.
There's almost always some kind of build up that has made at the right time in place for a particular development to take place, or at least that's how we can see it in retrospect. So in this case, what was going on in the world in sixteen seventy four
that had set the stage for laven Hook's discovery. So at the time that laven Hook was looking through his microscope at this previously undiscovered world, the scientific world was undergoing something of a revolution, and maybe more accurately, was
being born. Whereas in the past it was enough for someone to rely on the words or the writings of those ancient philosophers who had come before, the trend was shifting towards emphasis on data that you obtained empirically through observations, and this often meant personally observing the phenomenon that you were interested in, then publishing your observations, and then having
other people independently confirm what you had seen. But these people who were not yet called scientists needed tools that would enable them to accurately measure whatever it was they were interested in and produce consistent results across other observers. And as we know, necessity is the mother of invention, and during the seventeenth century a lot of invention happened. So all kinds of empirical tools were developed that expanded
the realm of human observation. The thermometer, the barometer, the pendulum clock, the telescope, the microscope. These things were all either invented or developed to the point where they were in almost wide use.
That's so cool, it's so cool.
And these because these tools also they turned these personal experiences into impersonal numbers. The subjective in describing natural events decreased, but the words that were used to describe these observations became more specific and more relatable across cultures and languages.
Oh wow, I never even thought about that aspect of it.
Yeah, it really did sort of flatten the globe, I guess, or in terms of in terms of advancing knowledge and saying to be able to say how hot is it? It's pretty hot, or it's this many degrees? Although here I am you know Celsius and Imperial. That's okay, we won't get in. We have calculators now, yeah, exactly, we have Google, Google filth. Yeah. This fascination with empiricism extended beyond those that were studying mathematics or geography or the
natural world. This time, so like the mid sixteen hundreds, the sixteen hundreds to seventeen hundreds was a time of observation of recording. Surveyors would map the land while astronomers mapped the sky, and painters use camera obscuras to record scenes from life, while natural historians recorded the plants and
animals around them. In this time, also, the boundary between artists and scientists was thin, so some of those that consider themselves catalogers of the natural world had been trained in painting or drawing, because how else could you relay
what you were seeing or observing. Right and Dutch artists in particular were becoming more detail oriented, with the tendency for art during this time to be more about what is directly observed, rather than telling a story or idealizing a person or place by ignoring or glossing over the flaws.
This general focus on recording and realism during this time is I think a really important part of the story of microscopy, because for the first few decades of its existence, the microscope was primarily used to demonstrate the wonders of the natural world. Look at this super cool grasshopper. Look at this tiny mite living in your cheese.
This animal keule, what does he call them?
Animal cule? Yeah, And while telescopes shortened distance, bringing far away things closer to the eye, those things were already generally known to humans. Just far away. You could see that that star, or that planet or that tree was there, but if you look at it through the telescope, it's closer. But microscopes, on the other hand, revealed this whole new world. And this, I feel like, would have completely shifted the perception of the natural world and what role humans play
in that. Yeah, it's really hard to imagine.
It blows my mind, quite honestly.
It's impossible. It really is unimaginable, Like to wonder at what that would be like to day, would be like discovering that we live in the tear drop of a giant.
I feel like it.
I mean, this is not as extreme, but I feel like it was how I felt the first time I ever went scuba diving. Mmm, I like sitting at the bottom of a kelp forest and looking up you realize just how like it's an entirely different world. And I feel like it's a similar. Look if you have no concept that things this small exist and then you look in a drop of water and you see this, it's like, what like it's yeah, yeah, that's the closest I can come.
I've read before that people who go to space astronauts and then they look down at the Earth, that their perception of world, of life, human of humanity is forever changed by that in a way that's yeah, that you can't imitate or mimic. And I kind of wonder whether that was it was similar to that being some of the first people to say, oh, like, there's a whole new world here and not just being told or seeing pictures of it.
I can't stop singing a whole new.
World every time it, by the way, every single time.
It's amazing. Yeah, but yeah, these microscopes could could reveal the tiny, tiny, little intricacy of a flea's leg, and how beautiful it could be to look at a spider's eye. Oh, it's amazing.
It's incredible.
Robert Hook was one of the first people to develop or to use the microscope in observation, and he had this groundbreaking book called Micrographia micro Graphia that displayed the exteriors of these tiny creatures or of everyday objects magnified to sizes never before seen. And think he had a fold out of a flea, for instance.
Oh, yeah, I've seen that. I've seen that. It's incredible.
Yeah, I want to get that coffee table book. Yes, I wonder if they make it. But the simple description of these things soon wasn't seen as enough. Some people were like, Okay, these microscopes are incredibly powerful tools that should be used to explore the inner workings of both living and non living things. How do things work? Yeah, just to use them only on making pretty drawings seemed
like a waste to a lot of people. Okay. So Laven Hook would not have been unfamiliar with microscopes or at least magnification using lenses, because as a cloth merchant, he had to inspect his fabric for thread count, So it makes sense that he would have maybe tried experimenting with lenses, especially considering the trend that had swept society because people were obsessed, fascinated by lenses.
Oh that is so funny.
They wanted to look at the mites crawling in their bread, the fleas and their dogs, anything and everything. By the mid sixteen hundreds, you could find lens stores in every marketplace, and wearing glasses even if you didn't need them, could be considered fashionable.
Okay, that's still fashionable today, isn't it. So nothing has changed.
Lens crafting varied in technique and quality, and imperfections in the glass led many people, including laven Hook, to experiment with making lenses of their own. After retiring from the cloth trade, laven Hook started to venture into lens crafting, first with bead lenses, which is where you melt the end of a glass rod over a flame and then you draw out a thread of glass, cutting off the
end when it becomes a bubble. What yep. And so from these bead glasses you could make powerful lenses, but with very short focal lengths.
Huh.
And because you were using flame to create them, you were going to make a lot of duds before getting a new one.
Okay.
So after bead lenses, laven Hook moved onto grinding and blowing glass. His obsession or patients maybe or maybe it was both rewarded him and his microscopes ended up being some of the best known during this time in his life. He made loads of microscopes of varying magnification and construction and quality, and estimated five hundred and sixty six total wow, of which sadly only nine survive, eight with lenses.
I thought, I remembered you saying that, like, he's got a whole cabinet full of somewhere that just disappeared from Yep.
It disappeared like he left it to the Royal Society after his death and somebody went to look at it in the mid eighteen hundreds and then the Royal Society was like, uh, we don't know where it is.
That's the most depressing.
Anyone who's thrifting or antique hunting in England. I think is where the is where the cabinet was last seen. Keep an eye, yeah, man, I think a lot of the other ones to the glass tubes were melted down, not the glass tubes, the gold tubes melted down for gold.
Ugh.
Yeah. But of those surviving lenses, of the eight ones that have lenses, the magnification range from sixty nine times to two hundred and sixty six times. What but he may have achieved even higher magnification up to five hundred times.
That's bananas.
He was probably the first person to see bacteria. He saw some on peppercorns.
Wow, I had no idea that he Wow.
Yeah, two twenty five is a lot already, I know, it's amazing.
That is very cool.
So Hook had shown the world this beauty and intricacy of things that humans already knew to exist, like the fold out flea. But Leaven Hook would reveal a whole new world, a brand new world. I'm just gonna keep saying, whole new world new. There we go that previously had been completely unknown. And he started out like Hook observing
visible things in miniature. But when he stuck some lake water under his scope is when he discovered that this microscopic teeming life that was present in not just lakewater, but rainwater and everything else.
Yeah.
It's hard to say whether even Laven Hook realized at first the magnitude of his discovery. He published his observations, but they were buried around twenty pages in his manuscript on other microscopic observations of things like the working of the eye, and so his description of this new unseen world wasn't met with much acclaim, and he kept sort of writing in with new observations, saying, oh, remember when I found this, like tons of microscopic life and rainwater.
They were very small. They were very small. And finally he was like, did no one read this? Probably not, No.
One makes it twenty pages in Anthony.
Uh uh, come on man. After his repeated writings, people finally did start to take notice of what he had said, and they were like, eh, really, come on. It was there was a little bit of disbelief happening because Lavean Hook was describing a world that was unimaginably small. He was describing living creatures ten thousand times smaller than the smallest thing perceivable by the naked eye. Jeez, it sounded like a fanciful story made up by a very creative
and bored person and retired du Yeah. The credibility of his findings also wasn't helped by his extreme possessiveness of his instruments. He was famous for jealously guarding the secrets of how he made his powerful microscopes, and this was super frustrating to the Royal society, who had no patience for people obscuring the methods behind their discoveries acting like magicians.
And that's I think reasonable, yecause how can you take someone at their word who claims that the water you drink, the rain that falls contains billions trillions of small animals invisible.
To the naked eye, right when it sounds absurd and they won't tell you how they made the thing in order to look at it, like that's right, yeah, yeah.
And he, you know, he recognized that this was standing in the way of the world accepting his immense discovery, but he was too stubborn to do anything about it. So what he did was he was like, all right, now you all can come here to look through the lens for yourselves. And they were like, we're not going to do that, man, we're in England. We're not going to go all the way to Delft. That's not that far. But and then so he was like, okay, fine, stay there,
don't come here. He got people to write, like to sign affidavits saying that they had seen this in his scopes, like okay, it's a little bit better, but we're still not content. So then the Royal Society was like, all right, we just need somebody else to do this. So then they pulled Robert Hook away from his workings of circulatory systems and respiratory systems because Hook had by now moved on from microscopy. And they were like, okay, Bob, will you try to replicate these findings?
Bob, can you help us out here?
And Bob did so he did eventually after a little bit of trying, find these animal cools that leaven Hook had supposedly seen. So that was pretty big step. His world was confirmed, and this discovery caused this major shift. Once it was confirmed by Hook, this it was reported, and it causes major shift in human perception because suddenly the world both grew and shrank. Some people were comforted by it, taking it as evidence of a divinely created world,
while others took a more nihilistic view. Yeah. For his part, laven Hook didn't stop at examining lake water or rain water. Once he had gotten a glimpse of those microscopic worlds teeming with life, there was no substance off limits. He looked at his own blood yours toothplaque pus gunk from between his toes after not taking off his stockings for two weeks.
Pretty gross.
Made that gross. He also looked at earwax semen, and of course his own feces, which is of course where he first spotted his sweet little Giaradia. One of the things that I think is really fascinating about the development of microscopy is how long it seemed to take for people to make the connection between the little microscopic animal cooles seen in sources of drinking water and diarrheal disease.
Even Lavenhok was so fond of his little animal cools that he would never have accused them of causing the diarrhea in which he found Giardia.
That's very adorable.
He loved them.
They really found them in his poop, Yes.
He loved I mean he loved the ones in rainwater. He loved the ones he missed them when he went away.
That's very adorable.
Yeah, okay, So going into Giardia a little bit now. It took almost two hundred years after laven Hook first observed Giardia in sixteen eighty one for it to get an official name, and even then it would be another one hundred years or so before it was officially recognized as actually causing disease in humans.
Does that mean we're talking about the nineteen hundreds, yes?
What Yeah? So in eighteen fifty nine, villain Duson lambole I probably said that wrong. Was a Czech scientist and he was examining the stool of a child found it teaming with Giardia protozoa. He called them circomonas in testinalis, but the name eventually was changed to Giardia Lamblia to honor Lambele and Alfred Gillard, who also described the parasite.
So to put the official discovery of Giardia in eighteen fifty nine into our history of disease timeline, that happened just a few years after the infamous Broad Street cholera epidemic in London, and as we remember from that cholera episode, the theory of mi asthma was in full swing at
that time. Of course, over the next few decades people would use microscopes to develop the field of germ theory linking a parasite or pathogen to the site of infection, and microscopes were also used to develop so many other fields, both in biology and chemistry, in physics and everything. It's they're been amazing.
I don't know why.
I was expecting that since it's a parasite, it somehow would have been earlier. But I mean, it's it's still I mean, it's still a microscopic. It's still you know, it's like malaria.
It's like, yeah, well it's still microscopic. But even when it was recorded and given a name in eighteen fifty nine, it was still just seen as an organism, right, not necessarily a parasite.
Yeah.
God, which is so interesting.
And I think so I yeah, I was thinking about this and I'm like, Okay, that seems like one of the easiest links to uncover between microbe and disease. Yeah, but it didn't seem like it got a lot of focus. And maybe that's because it was almost ever present and didn't necessarily cause a lot of obvious mortality or epidemics, even though it did cause occasional epidemics.
Yeah.
And if you can have just i mean, probably everyone was infected with it, so you're testing everyone's poop and not everyone is having diarrhea, you're still going to see giardia in everyone's poop, So you wouldn't think, Yeah, yeah, that makes sense.
So it's a little bit of a harder Yeah. And there were some researchers in the early nineteen hundreds that claimed that giardia was a common cause of diarrhea, and they had conducted experiments on both humans and animals to observe the effects of the infection, and they also had recorded their observations of gardioceis and English soldiers in like World War One, I think, but interest in the parasite
seemed to wane throughout the twentieth century. So the WJO officially declared it a human pathogen or parasite in nineteen eighty one, but it wasn't officially recognized as fulfilling all the pastas until nineteen eighty seven, and even after that it was still debated whether whether some some cases of disease could be attributed to the parasite.
Yeah, are surprised even yeah. Wow.
And this decline and interest I think was possibly maybe due to the massive reduction in waterborne infections throughout the developed world as water filtration increased. So I couldn't really find any good numbers for global prevalence of giardia throughout history. And that's maybe because it was only recently recognized as a human parasite, and possibly because it dropped off in
places that had the highest amounts of research funding. But even though I can't give you hard numbers, I can make some guesses, which is a statement that the seventeenth century Dutch society would have hated. It's very non empirical. Giardia has probably infected humans for Lena, as is evidenced by its global distribution and prevalence likely increased as humans settled and population density increased as water treatment and filtration
became more widespread. In the first half of the twentieth century, cases of intestinal diseases declined in many places, as did mortality from water borne diseases. So, for instance, in nineteen hundred, if you lived in the US, you had a one in twenty chance of dying of a gastrointestinal infection before you were seventy years old.
WHOA, yeah, a lot.
By nineteen forty that was a one in three thousand, three hundred and thirty three chance, and in nineteen ninety a one in two million.
Chants wow.
But for much of the world, the risk of dying of a waterborne disease remains staggeringly high, and giardia remains one of the most common infections and causes of morbidity out there. So Aarin, tell me exactly what we're dealing with in Gardi.
It's ada.
I'd love to.
We'll take one more quick break. It's funny that you said you couldn't find good numbers on giardia throughout history, because I couldn't find good numbers on girardia today.
What's the deal?
End of our episode? Just kidding.
This is the most slept on parasite out there.
So this is a disease that is so widespread that on the World Health Organization website page about grdiasis, it just says distribution colon worldwide. Wow, like legit, that's what it says. Somm. According to the CDC, nearly two percent of adults and six to eight percent of children in developed countries will be infected at some point in their lives with giardia, and nearly thirty three percent of people living in developing countries will have been infected at some point in their lives.
And we still don't exactly know how it causes disease.
Well, apparently it was like thirty years ago that we decided we'll call it a human pathogen. So when you hear that, it's not that surprising.
That's yeah, that is that's true. Yeah. Wow.
So it's by a long shot the most common human intestinal parasite diagnosed in the US. I did find a few numbers in one of the papers that I read reported at least a few numbers, so I'll give those to you. Between two thousand and six and two thousand and eight, in the US there were at least twenty thousand cases reported annually, and the estimated actual number was
closer to two million. And that's US, okay, And for you in Finland, In Finland, Norway and Sweden again in like the mid two thousands, they estimated that for every single case that was reported, there were likely between two hundred and fifty and eight hundred and fifty actual cases that went unreported.
Wow. Yeah.
And then throughout Europe the numbers really vary, like hundreds, two thousands to tens of thousands reported every year. It's so we just absolutely do not have a good handle on how many people are actually infected at all.
It's a real tip of the Iceberg situation.
And here's where it gets even more fun and even more tip of such a large iceberg erin this was thrilling to get to read. One of the biggest things that we absolutely do not have a handle on that we're still trying to figure out is in regards to how much overlap there is between cycles of this disease.
Between cycles, Oh, let's.
Talk about it.
So yes, As it turns out, there are several distinct cycles in which we can identify that Giardia circulates. There's wildlife cycles, so wildlife poop in the wild and infect other wildlife. Okay, that's a wildlife cycle of disease. There's livestock cycles where live stock on a farm poop on that farm and infect all the live stock on that farm. That's a livestock cycle. There's domestic animal cycles like dogs and cats infecting each other. And then there's human cycles
where humans poop and infect each other. The question that we don't know is how much overlap is there between these cycles and what kind of overlap is it. Are things being directly transmitted between wildlife and humans. Is it all waterborne transmission between wildlife and humans, Is it more cycling between livestock and humans, or between humans and livestock. Which direction do these spillovers occur?
And are there distinct.
Species or subspecies of Giardia being transmitted between these different groups or is it all the same parasite.
We have no idea, Aaron, but I imagine that there's work being done on geographical variants or subspecies or whatever.
Yeah, there's very very cool work being done on the molecular epidemiology of giardia.
It's very cool.
A couple of questions real quick, because you mentioned wildlife and livestock, What do we know about the prevalence in I know that this is a huge question, but like in general, is there much known about the prevalence of giardia in wildlife or different wildlife species? Everyone calls it beaver fever. We can't get through the episode without saying beaver fever? Yeah, and so what is the actual prevalence in beaver's And then the second question or fifteenth question, what about live stock?
Yeah?
Are pigs more likely than cows? Are chickens more likely than goats?
Where, Aaron, you're asking all the right questions, You're one hundred percent asking all the right questions.
I don't have the answers to all of them.
Aaron, Livestock are affected at very high rates in general, and a lot of times, if you end up with one, for example, infected cow on a farm, then you're likely to have every single cow infected on that farm.
So that's livestock.
It's very very common among livestock. How common it is among wildlife totally varies into depends on what type of wildlife you're talking about and where they are. I mean, because again, this is a disease. This is a parasite that's found across the entire globe.
Are there any species that don't get infected when exposed?
Oh?
Good question? Don't know? Okay, yeah, I don't have no idea.
The other thing is we have no we don't have a good grasp on whether it's distinct species or subspecies of Girardi, a parasite being transmitted among wildlife and livestock and humans. I know, I keep saying it with two arts, Just leave it.
I just keep thinking Girardi above.
Every time I see your face, I know I've said it wrong.
I'm tried to poker face this, but I can't.
You're failing at a poker face.
But there is a lot of molecular epidemiology work being done to try and figure this out, because who has classified this as a zoonotic pathogen, which means that you would expect that most of the transmission happens in a zoonotic pathogen between wildlife or other animals and humans. But in many cases that doesn't seem to be the case, and it might even be more likely that humans are actually infecting wildlife at just as high, if not higher rates than wildlife end up infecting humans.
Mm hmmmmmm mm hmm.
It's so cool.
So while there's no doubt that giardia can be a zoonotic disease, we don't know how frequently it's actually zoonotic versus just a human disease that circulates among human populations.
Also, quick question, what's the opposite of zoonotic?
Is it anth anthroponotic? Anthroponotic?
Fact checked me, I'm doing it, thank you anthroponosis, Yeah, anthroponoses Yep, there we go.
Perfect.
So cool, we don't know fully. I will post a link on our website to two very great reviews, one from two thousand and four another from twenty eleven that dive really deeply into this Don we don't have time in this episode to dive into all the different subgroups and subspecies and whether there should be multiple species of Girardia Giardia duat analyis or not, et cetera, et cetera.
But what I do want to say is it seems as though at this point a lot of the transmission and a lot of the outbreaks that we see in humans happen between humans human to human transmission. So while things like drinking surface groundwater from a mountain stream is absolutely a risk factor forgetting grdiasis, it's not like we can just blame it on the beavers.
Don't blame it on the beavers.
It's equally possible that that the water has been contaminated by humans or domestic or livestock animals.
Isn't that just so cool?
That's very interesting.
It makes so much more sense to me knowing that it's been so recent that people have even been recognizing this as a disease, because I was like, how do we know so little about the molecular epidemiology and like the distribution of this disease among wildlife and livestock and what species or subspecies are affecting humans versus wildlife, Like, it's bananas to me that we know so little, but there's very very cool research being done on it.
Yeah.
Good.
The other big field of research right now is in vaccines. So there does exist already a licensed vaccine for dogs and cats, but it's not great. It doesn't work very well. As it turns out. It decreases the shedding of cysts in the stool of dogs, but it doesn't actually prevent infection or reduce symptoms of the disease. So it's kind of if you're talking about giving it to your pet dog, it doesn't seem to actually be that helpful.
Hmm.
Okay, but that just means that there's room for new research. I found a very cool study that was published in twenty sixteen. It was a massive, massive study. Sometimes I look at these and I'm like, good lord, you put like six years worth of work into one paper. Whoof Yeah, but it was nature, so you know.
Yeah.
So this group developed a vaccine, a component vaccine that was actually a vaccine against the human genotypes that are more common among humans than dogs and cats. Okay, And it was a component vaccine, so just the surface proteins, not an entire killed parasite, which is what the vaccine
that's for dogs is today. So in this paper, they showed that this vaccine could both stimulate an immune response in puppies and kittens, so actually stimulated their immune system to develop antibodies, that this immune response was actually protective against infection with Giardia. So they exposed the puppies and kittens to gerardia, and then they vaccinated dogs and cats in a community and they found that it protected the puppies and kittens, the dogs and cats in that community
from infection. So over time, infection was less in the dogs and cats that were vaccinated. In fact, none of the dogs and cats that were vaccinated ended up getting infected.
After two years. WHOA, that's great.
Yeah.
On top of that, they tested children in that community, and infection in children in that area decreased over that time period as well. So in this paper they were suggesting that vaccinating dogs and cats against this specific species or subspecies, this specific genotype of Gerardia could actually help potentially prevent the spread of disease in humans.
Even huh.
Based on a lot of the other molecular epidemiology studies, it seems like that's very context dependent because in a lot of communities there's actually very little overlap between the genotypes of Giardia that circulate among dogs and those that circulate among humans. So it would really depend on so where they did this study in Argentina that happened to be true, but in another community it very well may not be. But it's still very cool, huh So, and again I'll post.
The link to that study as well.
Of course, So about the widespread prevalence of giardia and how problematic it is for nutrition and just overall health, what are the kind of secondary outcomes associated and like in terms of dalis or anything else like that.
So I couldn't find.
Numbers on that. A lot of the studies on Gerardia that look more at that Giardia becomes more important in cases.
Of co infection.
So when you have areas where you have really high rates of coinfection with Gerardia and things like hookworm or other intestinal worms, that's when you see worse outcomes for people in terms of nutrition and malnutrition and things like that. But just looking at Gerardia alone, there's not a ton of great EPI data that I that I was able to find.
Okay, interesting.
Yeah, yeah, so yeah, that's pretty much jarediasis.
And Lasha how about it?
How about it? Don't swim in a pool if you have diarrhea?
Please.
Yeah, that's what I gleaned from all.
I have one more question for you. Okay, how scared should we be of Jaredia?
I think we should be scared that we know so little about it?
God, Okay, maybe it's other h Pylori.
Yeah, it could be.
It really could be, like who knows what this thing has been doing in our guts for so long?
Clearly causing lactose intolerance and all kinds of people.
And all kinds of things, ibs et cetera. Cool. That was fun sources, fun, okay, sources.
I'm gonna mention a couple of books that I read. One is called Drinking Water, a history by James Salzman, and the other one is called I of the Beholder Johannes vermir Anthony von Lavenhook and the Reinvention of Seeing. But that's by Laura Snyder. So if you just google Ie of the Beholder, you're going to get a lot of like bodice ripping romance novels. You have to put
in laven Hook or Vermiir. But this book was really interesting because it dove into both art history and the history of microscopes, and it was just a really sort of big picture history book. I really enjoyed it.
So, Melissa allman, if you're listening, you should read it.
You'll love this, Melissa. And then I've read some articles that I'll post the links to on our website.
Yep. As always, we'll post the links to all of our sources on our website. This podcast will Kill You dot com. You can find our sources from this and all of our episodes.
Thank you all for listening. Yeah, I really appreciate it.
Thank you also to Bloodmobile for the music in this episode and all of our episodes.
And stay tuned because you are going to get a wonderful song that if you listen to the Hookworm episode you've heard before, Parasite Love Song is gonna play us out. It's the best. Thank you so much to Merrimac Valley Girl for letting us play it again. And you can find her website at Merrimackvalleygirl dot com and she also has an Instagram m E r amec Valley Girl. All Right, until next time, Wash your hands, you filthy animals.
I cannot live without you, naughty, even for a day. Please don't try to push me out. Please just let me stay. It's a miracle I've found you. Introductions were not forced. They'd brought us together. Let nature take her course. You tried to avoid me, but my instincts were too good. Your defense is now arising, but I knew that they would. I never want to hurt you.
I don't want to make you.
Please do you understand me?
Do you know that I have needs?
Have you ever felt so wanted? I may be a fluke, our support may not be mutual, but please do not rebuke your giver. I'm a taker, but relations can evolve. I'll adapt to stay with you. Our problems can be solved. Oh what do I love about you? You're such a lovely host, your beautiful and rich inside where.
It counts the most.
I promise I won't cheat on you.
Please just let me stay.
I cannot live without you, not even for a day.
I want you out your magne sick.
I want you out your magne sick. I want you out your magnie sick. You're lousy and your magnie sick.
Also I just want to say you are my mother because you managed to fit in art history and microscope history in like the same sentence.
Listen, I read a great book. I'll shout it out at the end. Okay, I'll say, Melissa, you should listen to this, or you should read this.
She'll be like Aaron, I've already read it, just kidding.
Probs, we're friends on Goodreads, so maybe she's already seen that I've read it, and then she'll add it to her good Reads.
I love it.