Ep 94 Chlamydia: Double Trouble

had happened. I felt ashamed and dirty, angry both at myself and my partner. Thoughts like I'll never have sex again and my life is over flashed through my head. I even blamed the person my ex contracted it from. I felt betrayed by my partner, thinking how could you do this to me? But after a conversation with my doctor, who was very familiar with these cases, my assumptions about the disease were thrown out the window and replaced with a new understanding. A simple round of antibiotics and we'd

both be fine. I felt the stigma had dropped, and I wasn't shy to tell my story to let others in the same boat know that it isn't the end of the world, and that you are not defined by a diagnosis. I was proud to handle it the way I did. Then college came, and it followed me. I hooked up with a person who turned cold towards me. Days later, I knew something was off, and I asked them about it. They told me they heard about my past. They said that they had heard quote something about chlamydia

and it scared them. They were ashamed for being intimate with me as someone who was once diagnosed with this infection. They thought I was dirty and that it made them dirty too. The feeling of rejection cut deep, and I begged him to keep his voice down. Doing what I could, I told him some of the facts. I knew how men are usually asymptomatic, how antibiotics are used to treat it, condoms are one method of prevention, and how it can

increase the risk of pelvic inflammatory disease in women. Still, I was so angry and shocked that this had happened. Of course they didn't know better, but maybe they should have. I was upset both for the judgments they made about me, but also anyone who had been diagnosed with an STI. I thought to myself, why am I to blame? Why not my male partners? Why not the disease itself? What

blame is there to be had? Anyway? I have learned my lesson that what matters in sexual intimacy is not rumors and history, but who someone is at their core, and whether or not their values and understanding of the world aligns with yours. What's important is mutual respect and open and healthy communication. STIs can happen to you virtually anyone, and your value as a person has nothing to do

with your sexual health. You are not a diagnosis. I feel like that is just such an important message, right like you are not a die diagnosis.

that's difficult to do. And I just want to acknowledge that and say thank you, and also that it's so wonderful and impactful, because I feel like it really drives home that like, these diseases do happen, These things happen to people who are living their everyday lives. And yeah, I think it just sort of reinforces once again, you are not a diagnosis. Yeah. Yeah, Hi, I'm Erin Welsh and I'm Erin on an updike and this is this podcast will Kill You.

that infect humans. Primarily, that is Chlamydia pneumonia, which causes pneumonia so it infects our respiratory tract, and Chlamydia trachomitis, which is really the subject of today's episode. But other species can cause respiratory or eurogenital or chloacal or conjunctival infections in mice, birds, cats, pigs, marsupial snakes, turtles, guinea pigs, koalas, and probably other animals that I didn't mention, and some of these other species just as like a fun side note.

For example, Chlamydia citassi, if I'm saying that right, is often a zoonotic pathogen that can cause disease in humans. It causes a disease called cydycosis, but it's primarily a bacteria of I believe birds. Anyways, all of that to say that today we're focusing on one species of chlamydia, and that is Chlymydia trachomitis. This is a human specific bacterium. But there are at least thirteen, maybe nineteen different erra VARs, and these seri VARs cause different diseases kind of a

number of them. Let's get into it. Err of rs A, B, and C cause an infection of the eyes that's called trachoma, which can lead to scarring and blindness and is a really important major cause of blindness in many parts of the world. Cerr of rs D through K cause what most of our listeners are probably familiar with as chlamydia, the sexually transmitted infection, and then the L SERR of rs, of which there are several cause another sexually transmitted infection

called Lymphogranuloma veneerum. Oh, so it's like three different seer of R groups that cause three different types of diseases. More or less there's some nuance there. So what I'm going to do here is take a pretty big picture view and talk about what all Chlamydia trachomatis has in common, and then will go over the kind of different presentations

of those diseases. Because it turns out, even though each ser of R like infects different tissues and maybe causes slightly different diseases, there's a lot of similarities in terms of the basic biology of how this pathogen works.

and that probably is based on some specifics of their genetics. Okay, but as we'll see, especially the classically sexually transmitted zero vrs D through K actually have a fairly wide tropism. So it's also differences in just the kind of epidemiology of where you find them and who tends to be infected and things like that.

active form that replicates prolifically. And then we'll transition back into the infectious elementary body to leave our cells and go on and infect more cells.

vulnerable epithelial cells, you could get infected. That means eyes, nose, throat, penis, vagina anus primarily, and associated structures and like I kind of touched on a lot. The different err of rs have different tissue tropisms. So cerr vrs A, B, and C tend to like the epithelial cells of our eyes and our nose. That's their preferred tissue tropism. That's where they do the best d through K most often infect our genital tract, but can also absolutely cause infection in

eyes or throat. And then the l zer of rs, the ones that I think we think of the least often. They also tend to be sexually transmitted, so primarily infect the anogenital region. But what's really different about the l serra rs is they have a tendency to invade past just that epithelial cell layer and cause a much deeper infection, which I think is fascinating and really does set them apart from the other seer.

reaction from us. And so what we'll see when we talk about the different symptoms is that while those symptoms are going to vary, of course depend on what tissues infected, depending on which mucous membrane is exposed, the inflammatory reaction itself is universal, and as we talked about in our endometriosis episode, that inflammatory reaction that our body generates can often result in scarring, and this scarring can have chronic

or long term consequences. And that's across the board regardless of tissue type. So when we talk about chlamydia, there's always the acute initial infection, but then there's also the potential for this inflammation to cause scarring that can cause more permanent or progressive damage.

just kill it. And instead, what chlamydia tends to do is modulate progression through the cell cycle in a way to try and promote chlamydia's own growth and survival for as long as possible. So I suspect that the inflammatory response is more of a like a last ditch, like, let's do what we can. So it's this constant battle between this bacteria that's inside of our cells and our body trying as best it can to fight it off, but then causing damage in the process.

nose secretions. So think rub your eye on your hand and then touch somebody else, or you know, you're nuzzling with your baby, snuggling with your kid and you get their goopy eyes and nose all over you, or you're sharing a towel. It can also be transmitted by I seeking flies. Although the relative importance of I seeking flies and all of these various modes of transmission, it's a little bit like we don't know which is the most important.

But anyways, as an acute infection, an initial infection these err rs are of Chlamydia trachomatis cause a mucopurulent conjunctivitis, so an infection of the eye and the conjunctiva, and it generally is self limited, like you asked aaron, it usually resolves. However, reinfection, especially in children, is incredibly common

in endemic areas, and so trichoma. The disease that results is the result of either longitudinal, continued active infection, which can also occur if you don't completely clear it, or chronic inflammation that results because of repeated infection, and this inflammation can actually persist even after infection is resolved. And in either case, whether it's a you know, continual infection or continual reinfection with inflammation, it results in significant scarring

to the eye and to the cornea. So it tends to be young children who are infected frequently and recurrently, but this scarring takes place over the course of decades, and what really happens is that the scarring it causes the upper eyelid to kind of turn inward, which then eventually progresses to something called trichiasis, which is when the eyelashes in turn and begin rubbing against the eye like sorry, I know, eyes are difficult.

is what leads to blindness, gotcha. And so the prevalence of scarring and blindness in adults relates to their exposure as children, which is kind of an important like public health concept because it's an acute infection that then causes this chronic disease in chronic scarring.

SERI VARs that tend to cause anogenital infections. So in people with a penis, chlamydia loves to infect the cells that line the urethra. Inflammation in this area is going to cause a urethritis, inflammation of the urethra. Often it's called non gonococcal urethritis, which I think is just so silly because it just means like, well, it's not gonorrhea.

have infection in someone with a CERFX. In a sexually transmitted chlamydia infection, the cervix is pretty high up in the vagina, and so even if you do have that mucopurulent discharge, which is what you may have, you might

not notice. It might not be painful, you might not have any other symptoms, and so you can have things like a little bit of bleeding after intercourse or if you did like a speculum exam, you might see the cervix look a little bit swollen or have a little bit of bleeding if you did a swab, but you might not feel that necessarily or notice it in terms of symptoms. That makes sense.

Phillipian tubes. So it can cause an endometritis, which is inflammation of the endometrium the cells that line the uterus, or a salpingitis, which is inflammation of those Filipian tubes. And if an infection ascends into the uterus and the Philippian tubes, that can become a persistent infection known as

pelvic inflammatory disease. And that inflammation, just like it can happen in the eyes with the trichoma serre of ours, can cause a lot of scarring over time, and this scarring is a big risk factor for both infertility as well as ectopic pregnancy, which can be a life threatening emergency.

to our lymph nodes and cause a more systemic infection. Now, what's interesting about this especially is that it used to be considered a relatively rare disease in high income countries and classically was described as like a painless ulcer followed by lymph node swelling, et cetera. But over the last few decades has become a much more common pathogen that more predominantly affects the anogenital region and can cause significant

inflammation in the rectum. In people that are having receptive anal sex.

spasm and be really painful. So the symptoms can actually be confused with inflammatory bowel disease because these symptoms really overlap. Huh h.

I don't know the answer to that. We don't know the answer to that. It's really unclear if this reactive arthritis is caused by a persistent chlamidial infection or if it's caused by just our immune response causing this inflammation that that becomes more widespread. Chlamydia is not the only cause of reactive arthritis. Salmonella, Camplobacter your senia, a lot

of other bacteria are also associated with reactive arthritis. But one of the pepers that I read said that up to four percent of people with an acute Chlamydia trichomitis infection go on to develop reactive arthritis, which is way higher than I thought.

really up for debate right now. So it's unclear. It's one of these areas that, much like so many you know, chronic and autoimmune inflammatory conditions, again, is ripe for research because we just don't really understand this reaction.

one time dose of az atherrmycin. But now there's more data that shows that actually curates are better with doxycycling, even though it's a longer course it's seven days. So yeah, antibiotic resistance is definitely a thing. I think it's not yet as severe as say, with gonorrhea, but let's hope we don't get there.

And then there's the trachomatis or trachoma part of the story, So the bacteria as the cause of this ie infection, the severe chronic eye infection. Yeah, and that's kind of how I decided to approach this history, except for the fact that I am going to be giving trachoma more airtime than chlamydia as an STI, partly because and I was a bit surprised to find this that trachoma has a much deeper and a much more extensive history than Chlmytia as an STI, because that was really only recognized

as an STI fairly recently. Really yeah, which, of course it doesn't mean that it only emerged as an STI recently, but in terms of like clinical recognition, yes, huh yeah, so kind of like you did. I'm gonna start with the evolutionary history overall, and then I'm going to go into tracoma and then talk a bit at the end about chlamydia. So I'm going to call this the trachomitus

chlamydia approach. I love it, thank you. For quite a while, people thought that chlamydia were mainly mammalian pathogens, infecting mammals and a few other animals intracellularly. But then in the late nineteen nineties, some researchers observed chlamydia acting as endosymbions inside free living amibe. They're not in the same genus like, for instance, one is called parachlamydia, but they are related

to these intracellular pathogens. Okay, okay, yeah, And this showed that not only are chlamydia way more diverse than people previously thought, but also much older, like seven hundred million years old. Oh that's yeah, But we're not going to

go through all seven hundred million years of history. Let's kind of get to where the human chlamydia specific strains or species that were interested in, right, So chlamydia trichomitis, essentially the strains of chlamydia that cause eye infections apparently diverged from the strains that caused genital infections around two million to five million years ago, which is around the

time that Homo habilis and Homo erectus evolved. So these guys have been with us for you know, like we said, as long as we've been human, yeah, forever, And ancient writings further confirmed that. So now is where I switched to focus on tricoma. Okay, So, even though tracoma has probably always impacted humans, the transition to larger settlements and decreased mobility would have provided more opportunities for the infection to spread to more people, both within communities and also

along trade routes. And its widespread prevalence is it's evident in the fact that trachoma is described in so many ancient texts, like so many really, Yeah, let's go through a few of these early mentions, starting with the more vague mentions and then getting more specific. There's a description from sometime during twenty six hundred to twenty seven hundred BCE about an emperor in China undergoing surgery for trachiasis.

And there are inscriptions of eye disorders found on animal bones and tortoise shells from around eleven hundred to sixteen hundred BCE. And there are also bronze age appellation forceps used for removing eyelashes found in Sumeria from around twenty six hundred BCE.

the eyelids was a commonly recommended treatment. Then we have writings from Sushruda from the seven hundreds BCE, who is an ancient Indian physician and surgeon that I've mentioned on the podcast at least a few times, like I think many times. Specifically, actually look this up in our diabetes, rabies, and organ transplantation episodes.

followed by the application of lizard or bat blood okay. Interestingly, both Plato and Aristotle suggested that tracoma was contagious, with Aristotle going so far as to suggest that you could get it just by looking at someone who had it. Oh yes, but it would take it quite a long time, of course, before they were vindicated in this belief. And we have another friend yet who is joining us, which

is Hippocrates and the Hippocratic texts. Yep. And in these texts there are descriptions of the fig like appearance of the upper lid and intern lashes, and also some suggestions that the condition could be prevented by avoiding the cold winds from the north and the warm winds from the south, which like, what winds are you left with?

the four stages of trachoma. I mean I could, honestly, I could go on and on this entire episode, just like listing these other ancient texts that have references to tracoma, like those by Avicenna and Alcohol the Ophthalmologist, among others. And also like you know that I would love to get into some of these, you know, these incredibly varied treatments used egg, white mouse, ear, frog's blood, the bile

of a goat, et cetera. But even without doing that, even without going further down this like rabbit hole of like ancient texts and tracoma, I feel like it has given us a pretty good sense of how widespread and devastating a problem this was.

mobility increase, and so on. Yeah, so I'm going to mention one more thing and kind of like olden times before jumping all the way ahead to the eighteen hundreds. Okay, So, during the Crusades in like eleven hundred to twelve hundred CE, a ton of crusaders and pilgrims that were venturing to the Holy Lands, and many of them came back with tracoma, one of them possibly being Saint Francis of Assisi, who was actually blind at his death in twelve twenty six.

sporadically or studied very intensively. But all of that would change around the early eighteen hundreds, and the reason for that change is, of course, war, specifically the Napoleonic Wars. Poor Napoleon has been featured on this podcast for way like so many times, for all of the disastrous campaigns where he was just basically his army was wiped out by various diseases. Right all the way back in season one,

we're talked about him in yellow Fever. In our Typhus episode, we talked about how an unbelievably huge number of his soldiers died from Typhus while trying to march up to Russia. But with Trachoma and Napoleon, we find ourselves not in Russia or Hispaniola, but rather in Egypt. From seventeen ninety eight to eighteen fifteen, Napoleon decided to wage a series of campaigns basically all over the place to try to gain more control over the European continent, largely by disrupting

British colonial and Econo rule. That was his aim. In July seventeen ninety eight, Napoleon landed near Alexandria Egypt, and then he and around forty thousand French troops marched to Cairo. And the purpose of the Egypt invasion, from what I can tell, was essentially to establish a foothold in the region so that they could try to disrupt one of the main sources of British economic power, India, by driving

the British out of that subcontinent. So they were like, all right, we're going to set up shop in Egypt and then from here we're going to just get like we're going to defeat the British. Okay, it also came with the plus of establishing French trade in the region. Not long after they arrived in Egypt, however, Napoleon's troops began to experience many of the illnesses you'd expect a traveling army to dysentery, excessive dehydration, and also eye infections.

By late September, the prevalence of eye infections or inflammation had grown enormously. For example, in one battalion of three hundred soldiers, one hundred and twenty five had ie inflammation severe enough that they were effectively blind wow and had to rely on their unaffected comrades to point their guns in the right direction from the trenches.

against the British. So everyone was affected essentially, is what I'm trying to say. And the British army seemed especially affected by eye inflammation after around March of eighteen oh one. One report from the time described how out of an eight thousand person division, sixteen hundred soldiers developed ophthalmia in September and October, and one hundred and fifty eight became blind just like a lot. That's a lot of people.

Napoleon's invasion of Egypt marked a turning point in the history of tracoma because it led to huge amount of interest in the disease, especially from military physicians, and it also led to the infection spreading much more widely. When these British and French troops returned to Europe from Egypt, many of them brought tracoma back with them, and basically

everywhere they traveled on their journey home, tracoma followed. For instance, French troops landing in Sicily in eighteen oh one on their way back from Egypt kicked off an epidemic of trachoma that didn't peak until twelve years later. Just rose and rose and rose. Yeah, oh my gosh. This time of the Napoleonic Wars and really in the years after was a period of great upheaval and mobility across huge parts of Europe, and trachoma was, you know, was not

alone in this. It was just one of the diseases that took advantage of this disruption and widespread travel. Tracoma moved from Sicily to Hungary, France, the Netherlands, Germany, Russia and on and on and on essentially everywhere, and it especially became a fixture in armies. Ophthalmia first showed up in the Russian army in eighteen eighteen, and within twenty years nearly eighty thousand Russian soldiers had been affected. Thousands of soldiers in the Dutch and Belgian armies became blind

or partially blind. And during the Crimean War, so like eighteen sixty one to eighteen sixty seven or so quote, four percent of all disability in the army was due to ophthalmia and five percent of the total discharges were because of blindness, although these rates were approximately half what they had been in the eighteen thirties. Wow yeah, So ten percent of the discharges being due to blindness in

the army, Wow yeah. And so you know, doctors, military doctors and also civilian doctors had plenty on their hands in terms of trachoma, And as you might expect, one of the things in the front of everyone's mind was how to control or prevent this disease, which, in the years before germ theory was tangled up with a debate

on whether tracoma was contagious or not. Was it warm rains or cool nights, was it a dusty atmosphere or a cold wind that led to outbreaks, or was it the sharing of hand basins, not washing regularly, sharing towels, not cleaning bedding, or not using pillowcases, etc. And in reality, it was kind of a little bit of both, because you know, having access to clean your face or not sharing towels one big part of it, and some environmental

factors playing another part through seasonal changes in fly prevalence, for instance. While some doctors continued to work on the control aspects of trachoma, others began to concentrate and specialize on how to treat the condition. The author of the book that I read for this compared tracoma to Helen of Troy, but rather than ships, tracoma was the disease that launched a thousand hospitals. I loved that by the mid to late eighteen hundreds, tracoma was a pervasive problem

everywhere and it wasn't limited to just the military. Entire hospitals and medical visions were created to treat it. And trachoma also played a big role in making ophthalmology a specialization and profession in itself, rather than it being just a part of generalist care. Like generalists who have an interest in ophthalmology.

until in nineteen oh seven. But knowing that trachoma was caused by an intracellular bacterium didn't stop people from characterizing the epidemiology of the disease. Familial transmission was common, children under seven had the highest prevalence, seemed to be strongly correlated with access to sanitation and clean water, and it

seemed to be most prevalent among low income households. And of course these last two characteristics, so low income households plus lack of access to sanitation or hygiene practices, these marked the disease as a social status indicator, similar to many other diseases that we've talked about on the podcast before, tuberculosis, hookworm, trachoma. These were the diseases that the poor brought upon themselves

just by being poor. That was like the narrative, right, These diagnoses became wrapped up in a person's identity, labeling them unclean.

was blamed on immigration. Throughout this time and into the early nineteen hundreds, millions of people were leaving their homeland, which was often somewhere in Europe, to travel to the US and try to find more opportunities, or be with their family, or escape some of the horrible situations that

were happening, like famine, many many, many different reasons. And I'm not going to go in depth about the immigration politics of this time because I don't know enough about it and there's probably better podcasts and resources out there, but I will say that as immigration increased in the late decades of the eighteen hundreds, so did resentment and anti immigration sentiments, which eventually led to policies aimed at reducing immigration by especially targeting people that they didn't want

to admit into the country, for instance the Chinese Exclusion Act of eighteen eighty two, or other laws or acts that prevented people from being admitted if they had certain disease, including but not limited to, epilepsy, quote insanity, tuberculosis, cholera, typhus, ringworm, and trichoma. In eighteen ninety seven, the US Surgeon General called trachoma quote a dangerous contagious disease, and instructed medical

officers to examine all immigrants. The examination process itself was painful and not at all sanitary, which probably led to further spread of trachoma. You're like, let me check your eyes. Okay, next, let me check your eyes. Oh you have tracoma. Oh let me check the next person's eyes.

took about six months. Whoa huh, because remember this is all pre any sort of effective right antibiotics? Antibiotics. Yeah. In nineteen oh two, the US ramped up their restrictions against tracoma by placing a one hundred dollars fine on every shipping company per tracoma case brought to the US. So then these companies started to do like port of origin screening sites, and these additional restrictions led to tracoma becoming one of the main reasons that prospective immigrants were rejected.

Let me read you some numbers to give you a sense of just how much tracoma played a role in immigration. Quote, between eighteen ninety seven and nineteen twenty four, some twenty one million, seven hundred and fifty eight thousand, eight hundred and seventy five immigrants were examined and thirty three thousand, eight hundred and forty seven were debarred because of tracoma. So it would be zero point sixteen percent. Wow. Another quote, it was common to have two to five percent of

prospective immigrations rejected. Eighty five percent of those rejections were due to tracoma.

were emigrating. For instance, Native Americans were among those most impacted, with an average prevalence rate of twenty three percent, but it gets worse. In some Native American boarding schools in Oklahoma, that number would shoot up to a horrific ninety two percent.

Ninety two percent, yeah, oh my. This report did kind of awaken public health officials to the tremendous issue that tracoma already posed in parts of the US, and so they created tricoma hospitals and state specific control programs, and over the early nineteen hundreds, especially the nineteen thirties and the nineteen forties, trachoma did sharply decline in the US and in many countries in Europe where it had been prevalent essentially countries that were like higher income countries, And

I think it's not the easiest thing to tease out exactly why this decline occurred and how much these treatment centers contributed versus infrastructural improvements in things like sanitation and clean water that made it possible for people to regularly practice like these hygiene practices that would help them keep

their face clean, et cetera. Based on the timing of the declines, it's possible that antibiotics like sulfonamides played a role, but if they did, I have to feel like it was a fairly minor one, since the decrease seemed to happen in many places long before the widespread introduction of these antibiotics.

which I know you'll talk more about, Aaron. Wasn't really until the mid nineteen hundreds that international organizations like the WHO started tracoma control programs for some low and middle income countries, and they set an elimination goal only in the mid nineteen nineties, which, honestly, it really surprised me after reading about this history, where I was like, wait, it's preventable, it's treatable, and it also has an absolutely enormous impact on quality of life.

But what the identification of chlamydia trachomatists did was allow people to distinguish trachoma from other acute types of eye inflammation, enabled them to see which treatments might work best, and also let them look for other ways that this bacterium could infect humans, such as genitally genitals. So let's go back in time to one chlamydia trichomitis was first identified. The late decades of the eighteen hundreds could be considered

the heyday of germ theory. People were identifying bacterial or parasitic causes of diseases left and right. I mean really, like, can you imagine the dissertation would be like I looked in this person's boogers and I found this boom give me a science or nature of paper. I don't think they existed back then, but in theory, in theory, yeah. And so when a disease existed that a bacterium or parasite wasn't easily like or readily identified, it wasn't like, oh,

this must not be infectious. It was often assumed that it was a transmissible, filterable agent aka a virus, and trichoma fell into this category at first, of course, until nineteen o seven, when Halberstetter and von Prowseek used a special stain to visualize the bacteria in trichoma, but they didn't realize at that time that it was bacteria they

were seeing. They thought it was intracellular protozoa that appeared to cloak the nucleus of the cells they infected, which gave rise to the name climytozoa, after the Greek word for cloak.

Gonerhea bacteria. It's hard to tease a part which historical descriptions of genital infections are actually gonerrhea versus something else based on symptoms alone, and the identification of Nicia Gonereea allowed people to finally say this is definitely gonerreea, which also meant that they could say, well, I don't know what this is, but it's certainly not gonereea, and we can't treat it with the same things as we do gonoreea. And so this is how non gonococcal urethritis or non

specific urethritis became a diagnosis. It was this diagnosis of exclusion that makes sense. People did look for the cause of non ganacoccal urethritis, which I'm just gonna call n GU moving forward, But one problem was that it wasn't just one thing causing it. Right later research has shown that it can be caused by chamydia trichomitus, mycoplasma, genitalium trichomonas, among others, but people didn't know it was like all

of these things could cause it at that time. Yeah, So if you're a researcher, let's say you're like digging in some secretions and trying to find out what the cause of this infection was, and you're like, I think I found it. I got it, And then you go over to a friend, take your little horse and buggy, go over to your friend and you say, I think I found it. Do you see it in your secretions? And he goes, no, I don't, this is something totally different. So you didn't get the right one right.

And I don't know how you pronounce this name, but I'm very excited about it because it is spelled wae lscch, which is very close to Welsh, and so I'm just going to call him Ludwig Welsh. And he described a quote rare form of NGU that had an incubation period of ten to fourteen days. The course of the disease was mild but long, and it was difficult to treat

using the antibiotics of the day. Additional work also showed that the mucous membrane in cases of Welsh erythritis, as it would be called, was reddened with soft multiple infiltrates quote like the nodules in tracoma. Interesting, people had made a possible connection with the tracoma agent and genital infections before this. One gruesome experiment even involved taking material from people's genitals who had NGU and then applying that to the eyes of monkeys, and sure enough they developed an

eye infection. There's definitely no io Cook approval on that one, for sure, no. But it seems like the tracoma agent was just a tricky bug to work with, and it was hard to know what it was or what it wasn't responsible for, including trachoma because there was still some debate about that, and also there was no ability at

the time to culture it. And even with well scheerithritis, sometimes people saw chlamydia in the scrapings of infected tissue under the scope and other times they didn't, but the link seemed strong enough for at least one researcher to suggest that this well scheerythritis was quote a genital tricoma.

The debate continued for decades, but in the nineteen thirties, American ophthalmologist Philip Thiguson drew a link between neonatal ocular infection and being exposed to genital infection during birth, and later that decade he also showed that trachoma could be treated with sulfonamides, which was actually a pretty huge, pretty

huge deal at the time. After the introduction of penicillin in the nineteen forties, which could be used to treat gonorrhea but not ngus, interest in NGU and the possible link between trachoma and genital infection increased even more. But the real turning point for both trachoma and chlamydia would come about in nineteen fifty seven. Earlier, when I said that scientists thought that trachoma could be caused by a virus,

they weren't actually that far off right. Chlamydia trichomatis acts like a virus in many ways, and this similarity to viruses, where they have to basically hijack a host sales machinery to replicate it kept researchers from being able to culture them for fifty years after their initial identification.

and so on. And two years after chlamydia could finally be cultured, it was isolated after delivery from both the cervix as well as the eyes of the infant who had inclusion conjunctivitis. People were finding more and more chlamydia in genital infections, and by nineteen sixty five, the number of cases of NGU, many of which were chlamydia, possibly most of which finally surpassed that of gonorrhea in the US, really illustrating how important it was to be able to

distinguish among these NGU infections right. It was no longer enough to just say there ngu, that's NGU. Finally, chlamydia as an STI became a clinical entity in the nineteen seventies w I no and even then it would be another ten or more years before it became a notifiable

disease in some places. In the nineteen eighties is when people started to discuss the possible ties between chlamydia and public inflammatory disease and infertility, and it seems like around the time of that research is when chlamydia began to be labeled as a disease of promiscuity, especially promiscuous women, which is really no different from how women were viewed historically as the sources of STIs, but not people who needed to be treated themselves, right.

that happen. Yeah. So Aaron, I would love for you to tell me more about where we stand with chlamydia and trachoma today.

for like global elimination, which sounds so great. But the initial target date was twenty TWENTYMWOMPOM, so the new target is twenty thirty.

so mass antibiotic campaigns and then also surgical correction to be able to reduce the progression of disease in people who already had it as children.

cases every year. That's a lot of cases, a lot of humans, with an estimated global prevalence of around four percent or so three point eight to four point two of people with a cervix so a cervical infections and anywhere from just under three percent to about seven percent were the estimates that I saw of people with a penis.

Surprisingly to no one, we don't have as good of data on penile urethral infections because most countries do not universally screen people with a penis for infection the way that they do screen young adult people with a cervix universally, which is again something that I hope will change in the next coming years. And importantly, it does tend to be young adults age eighteen to twenty six tend to

have the highest prevalence. So overall it's probably close to three to four percent of the population adult population infected at any given time. Got that's a lot of humans. And in the US as of twenty nineteen, there were over one point eight million cases reported annually. And if you look just at the highest risk group that we screen that we have good data on, that is people age fifteen to twenty four with a cervix, the annual incidence is over three thousand, seven hundred cases per one

hundred thousand people. Okay, that is incredibly common.

at risk for. When we're talking about sexually transmitted bacterial infection as common as this, anyone having sexual contact of any kind is going to be at some risk of infection. People having multiple different kinds of sex or sex with multiple people, of course, are going to have a higher risk. But whether you're having any type of sex with one person or multiple people, things like using condoms can decrease

our risk getting tested, getting treated. Talking about this infection and making it less shameful so that we have an awareness about it is the way that we reduce this infection. Because it's not that it's inherently bad or shameful to get a sexually transmitted infection, but they can be really serious, and we have ways to reduce the risk and to be able to treat these infections. So I think that's really important.

a spoiler. So far, still no vaccine, but of course lots of people doing fantastic research to get us closer.

We'll be talking about how these infections have led to declines in certain animal populations, as well as the latest news regarding a chlamythia vaccine for koalas. So make sure you don't miss it, because it's going to be great.