Speaker 1: On one occasion I spent the night with the brigade
Speaker 1: machine gun officer and the signals officer in one of
Speaker 1: the captured German dugouts. We tossed down for the night
Speaker 1: in the hopes of getting some sleep, but it was
Speaker 1: not to be. We no sooner lay down than hordes
Speaker 1: of lice got up. So we went round to the
Speaker 1: medical officer, who was also in the duckout with his equipment,
Speaker 1: and he gave us some ointment which he assured us
Speaker 1: would keep the little brutes away. We anointed ourselves all
Speaker 1: over with the stuff and again lay down in great hopes.
Speaker 1: But it was not to be, because instead of discouraging them,
Speaker 1: it seemed to act like a kind of ord'uv, and
Speaker 1: the little beggars went at their feast with renewed vigor.
Speaker 2: A full day's rest allowed us to clean up a
Speaker 2: bit and to launch a full scale attack on lice.
Speaker 2: I sat in a quiet corner of a barn for
Speaker 2: two hours, delapsing myself as best I could. We were
Speaker 2: all at it, for none of us escaped their vile attentions.
Speaker 2: The things lay in the seams of trousers and the
Speaker 2: deep furrows of long, thick wooly pants and seemed impregnable
Speaker 2: in their deep and trenchments. A lighted candle applied where
Speaker 2: they were thickest made them pop. After a session of this,
Speaker 2: my face would be covered with small blood spots from
Speaker 2: extra big fellows which had popped too vigorously. Lice hunting
Speaker 2: was called chatting. In parcels from home, it was usual
Speaker 2: to receive a tin of supposedly death dealing powder or palmade,
Speaker 2: but the lice thrived on the stuff.
Speaker 1: We had to sleep fully dressed. Of course, this was
Speaker 1: very uncomfortable, with the pressure of ammunition on one's chest
Speaker 1: restricted breathing. Furthermore, when a little warmth was obtained, the
Speaker 1: vermin used to get busy, and for some unexplained reason,
Speaker 1: they always seemed to get lively in the portion of
Speaker 1: one's back that lay underneath the belt and was the
Speaker 1: most inaccessible spot. The only way to obtain relief was
Speaker 1: to get out of the duckout, put a rifle barrel
Speaker 1: between the belt and rub up and down like a
Speaker 1: donkey at a gate post. This stopped it for a bit,
Speaker 1: but as soon as one got back into the dugout
Speaker 1: and was getting reasonably warm, so would the little brutes
Speaker 1: get going again. That's really funny.
Speaker 2: So those were all accounts of lice during trench warfare
Speaker 2: during World War One.
Speaker 1: It sounds truly awful.
Speaker 2: Erin, I just can't imagine. And I also have some
Speaker 2: numbers that I'll share later on just to kind of
Speaker 2: like put an even more horrific spin to this.
Speaker 1: Yeah, I lice, fleas, all the little things that just
Speaker 1: don't stop biting you.
Speaker 2: I know, I know.
Speaker 1: Yeah.
Speaker 2: By the way, those were from various soldiers from World
Speaker 2: War One and we will post the full names and
Speaker 2: links and whatever on our website. And also, Hi, I'm
Speaker 2: Erin Welsh and I'm Erin alman Updyke and this is
Speaker 2: this podcast We'll kill.
Speaker 1: You, And welcome to a very weird episode today.
Speaker 2: Yeah, we did not intend for this episode to be.
Speaker 2: We had no idea what we were getting into. We
Speaker 2: thought this was going to be a run of the
Speaker 2: mill episode. Yeah, and it's not. But that's okay.
Speaker 1: We were very wrong, but that means we learned something new.
Speaker 2: Yeah, of new things. Yeah, so what are we covering today, Aaron.
Speaker 1: Well, it's a good question. We're covering the genus Bartonella,
Speaker 1: which causes a whole bunch of diseases, some of which
Speaker 1: listeners you may have heard of, like cat scratch disease
Speaker 1: for example, also trench fever hence the lice in trenches,
Speaker 1: firs stand accounts, and also carry On's disease, Yeah, which
Speaker 1: you may not have heard of because I hadn't.
Speaker 2: Really I hadn't either, but I learned a lot about it,
Speaker 2: and I think it's actually going to be fun to do.
Speaker 1: I'm excited about it. I think it's going to be
Speaker 1: it's going to be at least I don't know something new.
Speaker 2: Yeah, yeah, And so this episode is going to be
Speaker 2: formatted a little bit differently, just as an explanation. What
Speaker 2: we're going to do is we'll go through the biology history,
Speaker 2: biology history, biology history in sort of like three mini
Speaker 2: episodes almost, and then we'll wrap it up with a
Speaker 2: current status. And that's kind of how it'll be.
Speaker 1: It's like three episodes for the price so one.
Speaker 2: Yeah, I'm saying, yeah, look at it that way. Certainly
Speaker 2: the work felt like three episodes for the price of one. Yep.
Speaker 1: So, speaking of which, I think it's about quarantine Hede.
Speaker 2: It is of what are we drinking this week?
Speaker 1: We're drinking a game of Cat and Laos.
Speaker 2: I love this name.
Speaker 1: I also do too, even though the cat scratches really
Speaker 1: flees more than lace, but I know it's still really good.
Speaker 2: Yeah.
Speaker 1: What's in a game of Cat and Laus? Aaron?
Speaker 2: In a game of Cat and Laos is gin peach nectar,
Speaker 2: sparkling water, some lemon juice, and then garnish it with
Speaker 2: a little fresh sprig of rosemary. Yum.
Speaker 1: Yeah, and we'll post the full recipe for that quarantini
Speaker 1: as well as our non alcoholic place Bareta, on our website,
Speaker 1: this podcast We Kill You dot com, and on all
Speaker 1: of our social media channels as always.
Speaker 2: As always, and business our website, you can find lots
Speaker 2: of things. You can find transcripts, you can find our
Speaker 2: references to all of the episodes. You can find a
Speaker 2: good Reads list, a bookshop dot Org affiliate account, a
Speaker 2: link to all of our promo codes that we talk
Speaker 2: about in the ads Patreon. I mean, I'm probably missing
Speaker 2: many things, merch but if I've missed it, just go
Speaker 2: to our website and you'll be able to find it there.
Speaker 1: It's true, there's a lot there.
Speaker 2: Yeah. All right, Well, should we get started on this
Speaker 2: very unusual episode?
Speaker 1: I yeah, I'm excited about it. Let's take a break
Speaker 1: and then dive into the first of three minisodes. Yeah,
Speaker 1: so suffice to say, I severely underestimated the genus Bartanella.
Speaker 2: Oh, same, same, same, So just.
Speaker 1: Upfront, what I'm going to do in this biology section
Speaker 1: is kind of go over the genus and all of
Speaker 1: the general things that we know about the genus Bartanella
Speaker 1: and the many species of bacteria that cause disease in
Speaker 1: humans and other animals, and just sort of go over
Speaker 1: the similarities and then focus on one specific species, and
Speaker 1: that is Bartanella bacilliformis, and that's aaron what you're going
Speaker 1: to then cover, et cetera, et cetera. Okay, And what
Speaker 1: makes this even more confusing is that even though we're
Speaker 1: going to focus on three specific bacterial species, there's like
Speaker 1: five or six or maybe seven, depending on how you
Speaker 1: count them, different diseases that they cause.
Speaker 2: Yeah, and there are some species that are not human
Speaker 2: specific or like not commonly human pathogens, but do infect humans.
Speaker 2: But we're not gonna go into those, yep.
Speaker 1: So let's talk about them all in general, shall we. Yes, So,
Speaker 1: in general, the genus Bartanella are small, fastidious, which we
Speaker 1: know means difficult to grow in culture.
Speaker 2: I love that word.
Speaker 1: I know it's such a good word. Gram negative rod
Speaker 1: shaped bacteria. There are dozens of species over thirty that
Speaker 1: we've identified so far, but again we're gonna focus on
Speaker 1: three today. But know that there are others that can
Speaker 1: cause some of these same diseases, and there's probably more
Speaker 1: that we just don't know about yet. I think that aarin,
Speaker 1: you're gonna talk a little bit more about the overarching
Speaker 1: evolutionary history. But it does seem that there are a
Speaker 1: lot of species that are relatively specific to certain mammals,
Speaker 1: like there are some species mostly found in rats, and
Speaker 1: others mostly found in cows or cats, et cetera. Yeap,
Speaker 1: and there's two species that will focus on today that
Speaker 1: are specific to humans, and then another species that commonly
Speaker 1: infects humans even though it's a feline species. Simple, simple,
Speaker 1: no problem, No one's confused yet. In general, these bacteria
Speaker 1: are transmitted to these mammalian usually mammalian hosts, by blood
Speaker 1: feeding arthropod vectors. But of course they're not simple, so
Speaker 1: it's not like just one type. Sometimes it's sandflies, sometimes
Speaker 1: it's lice, sometimes it's fleas. Maybe it could even be ticks.
Speaker 1: Some people are saying mm oh goodness, and if anyone
Speaker 1: listening has heard of cat scratch disease, you might already
Speaker 1: be scratching your head, scratching like I'm sorry, I thought
Speaker 1: the cat scratch disease was from cat scratches. And we'll
Speaker 1: get there. People will get there. But for the most part,
Speaker 1: these are vector born pathogens. But to make it even
Speaker 1: more confusing, unlike many vector born pathogens that we've covered
Speaker 1: on this podcast that are picked up in the blood
Speaker 1: stream and then spit out in their next blood meal
Speaker 1: to infect another host, these ones are sometimes transmitted that way,
Speaker 1: like when it's sandflies, but sometimes they are picked up
Speaker 1: in a blood meal and then replicate in the guts
Speaker 1: and then are pooped onto the mammal and then have
Speaker 1: to be scratched into a bite wound. So these are
Speaker 1: complicated bacteria, yeah, And then once they get inside their
Speaker 1: mammalian host to be even more complex. Bartnella exists as
Speaker 1: intracellular bacteria, so they don't just live inside us and
Speaker 1: replicate like say staff or strep or many other bacterial species.
Speaker 1: But they're more like Legionella that we just talked about,
Speaker 1: or chlamydia, gonorrhea, et cetera. They enter ricketsia, they go
Speaker 1: inside of our cells and replicate the way that viruses
Speaker 1: do in mammals, not in the arthropod vector.
Speaker 2: It's kind of impressive.
Speaker 1: I know, it's very cool. They're facultatively intracellular. Yeah, it's
Speaker 1: very very awesome. So that was all the really complex part.
Speaker 1: Let's talk about what they all have in common once
Speaker 1: they're in mammalian hosts, because it's actually kind of simple
Speaker 1: and tells us a lot about the diseases that they
Speaker 1: tend to cause. So, in mammals, Bartanella tend to infect
Speaker 1: two different cell types, two different kind of tissue types,
Speaker 1: red blood cells, erythrocytes and endothelial cells, which are the
Speaker 1: cells that line our blood vessels and can also be
Speaker 1: found in places like lymph nodes. They can also infect
Speaker 1: white blood cells and those two cell types. Infecting and
Speaker 1: causing damage to those two cell types actually explains a
Speaker 1: lot of what we see in terms of the actual
Speaker 1: symptoms of disease. Right, So at least that's one thing
Speaker 1: that they tend to have in common. Asterisk cat scratch
Speaker 1: disease is weird, all right, So that was all of
Speaker 1: the general details. Let's focus now on one species, Bartonella bacilliformis. Listeners,
Speaker 1: you may have never heard of this, because I had
Speaker 1: never even heard of it. This is a particular species
Speaker 1: that is human specific, so it doesn't infect, as far
Speaker 1: as we can tell, other mammals, at least not naturally,
Speaker 1: and it causes a disease no known as Carrion's disease.
Speaker 1: My accent is probably terrible on that, but also sometimes
Speaker 1: Carrion's disease is called two different diseases because this is
Speaker 1: a bi phasic illness, so there's an acute stage and
Speaker 1: then a potential chronic stage. And these two phases are
Speaker 1: completely different.
Speaker 2: That is fascinating, and I don't understand it, and I
Speaker 2: kept confusing the two phases, and.
Speaker 1: Yeah, well, hopefully when I explain it, the two phases
Speaker 1: will make at least a little bit more sense.
Speaker 2: Okay.
Speaker 1: So this particular species is vectored by sandflies in the
Speaker 1: same genus that we talked about with leshmaniasis of all things,
Speaker 1: Lutzomia sand flies.
Speaker 2: Yep.
Speaker 1: And part of the reason that many listeners may have
Speaker 1: never heard of it is that it's very geographically limited
Speaker 1: to certain parts of the Andean valleys in South America,
Speaker 1: so Peru, Ecuador, and Colombia, and only parts of those countries.
Speaker 2: It's like a really narrow altitudinal range, right, Yes, and
Speaker 2: it's where this particular sandfly species is found.
Speaker 1: Yeah. Yeah. So let's go over the symptoms of this
Speaker 1: one disease, Carrion's disease, which is sometimes called two different diseases.
Speaker 1: In the acute stage, which happens the first time that
Speaker 1: somebody gets infected, and the symptoms start usually about sixty
Speaker 1: days after infection, so it's a really long incubation period.
Speaker 2: WHOA, I did not know it was so long.
Speaker 1: Yeah, And some estimates that I saw ranged from ten
Speaker 1: to two hundred days. And I wonder how much of
Speaker 1: that variability just has to do with how little we
Speaker 1: really know about this disease quite honestly.
Speaker 2: Yeah, this was like, this was the one that was
Speaker 2: the most difficult to get information on.
Speaker 1: I think absolutely.
Speaker 2: So.
Speaker 1: The acute stage of Carrion's disease is sometimes called auroya fever.
Speaker 1: What it looks like is a headache, some general feeling
Speaker 1: cruddy like malaise, maybe some joint pain, bone pain, and
Speaker 1: that will progress to chills and a fever. But then
Speaker 1: over the course of one to four weeks, this becomes
Speaker 1: much much worse. People infected become pale, jaundiced, they might
Speaker 1: have difficulty breathing, they might become confused, and this can
Speaker 1: progress to multi organ failure and death. And some reports
Speaker 1: say that the mortality rate is anywhere from forty to
Speaker 1: eighty eight percent if untreated.
Speaker 2: Yeah, which blew me away.
Speaker 1: Yeah. Same, And I'm going to talk about it in
Speaker 1: a little bit more detail in a second, but first
Speaker 1: I want to talk about what's happening in this acute
Speaker 1: phase of the disease because it goes back to what
Speaker 1: we already know about this genus of bacteria. What's happening
Speaker 1: in this acute phase is that these bacteria are multiplying
Speaker 1: inside of our red blood cells. We know that that's
Speaker 1: one of the cells they like to infect, but in
Speaker 1: the case of this particular species, Bartnella bacilliformis these bacteria
Speaker 1: replicate rapidly and enormously into like huge numbers, and then
Speaker 1: they end up bursting open those red blood cells. So
Speaker 1: this can cause a severe hemolytic anemia that combined with
Speaker 1: secondary bacterial infection, is what often causes death.
Speaker 2: Why is there secondary bacterial infection.
Speaker 1: I'm not entirely clear, but likely it's just how overwhelmed
Speaker 1: the immune system is already makes you more susceptible to
Speaker 1: secondary infection. You have an overwhelming bacteremia, so so much
Speaker 1: bacteria in your blood already, your immune systems probably just
Speaker 1: not able to fight off other organisms.
Speaker 2: And so in that very why incubation period, once symptoms
Speaker 2: do start to appear, what's sort of the timeline there.
Speaker 1: From what I could gather a number of weeks, So
Speaker 1: one to four weeks is when these symptoms sort of
Speaker 1: start and then progress. Okay, but I want to get
Speaker 1: into it a little bit more because there's actually some
Speaker 1: evidence from some more recent outbreaks that have happened in
Speaker 1: non endemic areas that the mortality rate might actually be
Speaker 1: a lot lower, not just because of good treatment, which
Speaker 1: can certainly help, but it's likely the case that there's
Speaker 1: actually a lot more subacute or subclinical like not symptoms
Speaker 1: or barely any symptoms where people get infected but they
Speaker 1: don't even really know that they're sick. That happens that
Speaker 1: we didn't know about when it was just the people
Speaker 1: coming in really really sick, and then dying. Does that
Speaker 1: make sense?
Speaker 2: Yeah, No, I saw that also, and it maybe wonder
Speaker 2: why does that happen, Like why are there certain people
Speaker 2: because like from the history, so it doesn't seem to
Speaker 2: be like people who are already like immunocompromise. It doesn't
Speaker 2: seem to be like people who are in advanced age
Speaker 2: that are more likely to die. It just seems sort
Speaker 2: of random, almost.
Speaker 1: Right, Yeah, I honestly don't know. This was a disease
Speaker 1: that was really difficult to get like super clear information
Speaker 1: on likely because it is pretty rare.
Speaker 2: And then those non endemic areas, that is where it
Speaker 2: might be a different species of sand fly.
Speaker 1: Or potentially different species of sandfly, which could mean like
Speaker 1: a variant of the pathogen itself, So who really knows,
Speaker 1: quite honestly.
Speaker 2: Yeah.
Speaker 1: But in those outbreaks, though, what they found is that
Speaker 1: over seventy five percent of a population had antibodies, so
Speaker 1: lots of people were getting infected, but only about fourteen
Speaker 1: percent had symptoms of or ruya fever this initial infection,
Speaker 1: and then about seventeen percent went on to develop the
Speaker 1: chronic form. And what's even more interesting is that only
Speaker 1: five percent had this biphasic illness where they first had
Speaker 1: to arroya fever and then they went on to develop
Speaker 1: chronic form. But a lot of people had the chronic
Speaker 1: form quote unquote chronic without ever having symptoms of a
Speaker 1: royal fever.
Speaker 2: Okay, that is very interesting. So one of the questions
Speaker 2: that came up while I was reading was that, you know,
Speaker 2: it seems that this is human specific, and so that
Speaker 2: means that there would be no reservoir animal that we've
Speaker 2: found yet, and so are people just like reinfecting the
Speaker 2: flies forever? Like, how has this not burned through unless
Speaker 2: it is this high rate of subclinical cases that lead
Speaker 2: to just persistent like pathogen presence exactly.
Speaker 1: And honestly that that probably is what it is based
Speaker 1: on how Bartonella exists in so many other reservoir species. Right,
Speaker 1: it's very common to have a chronic bloodstream infection that
Speaker 1: kind of you'll have a lot of bacteria in the
Speaker 1: bloodstream and then you know, the numbers will decrease and
Speaker 1: it'll sort of cycle like that, even without having any symptoms.
Speaker 2: Yeah.
Speaker 1: So, but speaking of symptoms, the chron quote unquote chronic
Speaker 1: disorder that you can get which can happen I didn't
Speaker 1: get a timeline on how long after initial infection this
Speaker 1: tends to happen. But what can happen over a course
Speaker 1: of time is a disorder known as viruga peruana. And
Speaker 1: this is a cutaneous so a skin disease, and you
Speaker 1: get these little vascular tumors. Really, these little lumps or
Speaker 1: bumps or nodules. They look like little red or sometimes
Speaker 1: purple almost black, raised moles, like not quite wordy looking,
Speaker 1: but almost like a very red or per purple lumpy
Speaker 1: lump just stuck onto your skin, right, yeah, And they
Speaker 1: can actually have quite a lot of different appearances. Sometimes
Speaker 1: that's what they look like. And they're little and tiny,
Speaker 1: like less than three millimeters and just all over your body,
Speaker 1: especially on your arms and legs. Sometimes they can be
Speaker 1: a bit larger or even have like multiple little nubbins
Speaker 1: all in one, or sometimes it can manifest with deeper
Speaker 1: kind of subdermal nodules. And when those are present near
Speaker 1: a bone, like say right on top of your shin,
Speaker 1: for example, those can be kind of painful. But the
Speaker 1: reason that these are red to purple to dark black
Speaker 1: in color is because they're actually derived from vascular tissue.
Speaker 1: So these little lesions are made from blood vessels that proliferate.
Speaker 2: That's wild, uh huh, But.
Speaker 1: It's not that wild when you know that this bacteria
Speaker 1: infects the lining of our blood vessels. So it's basically
Speaker 1: just the bacteria causing peration of blood vessels in which
Speaker 1: it lives.
Speaker 2: That is ridiculous.
Speaker 1: Uh huh, wow, I know. And so these continue to
Speaker 1: develop often over the course of three to six months.
Speaker 1: You can imagine that because these are literally like made
Speaker 1: from blood vessels, it's very easy if you scratch them
Speaker 1: for them to open and bleed pretty profusely, more than
Speaker 1: like a normal mole would bleed if you scratched it,
Speaker 1: especially on the arms and legs. But in general, they
Speaker 1: tend to heal on their own, even without antibiotic treatment.
Speaker 2: Huh okay.
Speaker 1: Yeah, it's a very interesting and I think that a
Speaker 1: large part of the reason that they are able to
Speaker 1: heal on their own is because in general, with this
Speaker 1: disorder Veruga peruana, or the chronic form of carrion disease,
Speaker 1: these nodules tend to be limited to the skin and
Speaker 1: maybe a little bit deeper into like the subcutaneous tissue
Speaker 1: or maybe rarely the muscle, but they don't go any
Speaker 1: deeper than that. That's an important for a different disease
Speaker 1: that we'll talk about later. Okay, who was that enough?
Speaker 2: That was a lot, Aarin, No, I feel like I
Speaker 2: feel like this is going to be instead of three minisods,
Speaker 2: this is going to be three full maxi sense full maxisos.
Speaker 1: But so that kind of sums up the genus that
Speaker 1: is Bartonella and then Bartonella bacilliformis in specific. I think
Speaker 1: that that particular species is a good example of not
Speaker 1: only how severe this disease can get, but also why
Speaker 1: it's able to cause the diseases that it causes. Right,
Speaker 1: we'll go over the other two species that most commonly
Speaker 1: cause disease in humans later. But Aarin, first off, can
Speaker 1: you walk us through the history of this disease.
Speaker 2: I can, and we don't even have to take a
Speaker 2: break first. Yes, So, like you, Aaron, I wanted to
Speaker 2: start out with a general overview of the group of
Speaker 2: bacteria that we're talking about today, because even though the
Speaker 2: human histories of each of the three species we're talking
Speaker 2: about are very distinct from one another, being in the
Speaker 2: same genus of course means that they share an evolutionary
Speaker 2: history and it turns out that evolutionary history is actually
Speaker 2: pretty interesting.
Speaker 1: Of course.
Speaker 2: Uh so, the genus Bartanella is a fairly like you mentioned,
Speaker 2: diverse group of bacteria that tends to, though not always
Speaker 2: show high host specificity for its mammalian host or arthropod vector.
Speaker 2: And side note, it wasn't always known to be diverse.
Speaker 2: Until nineteen ninety three, the genus consisted I think of
Speaker 2: just Bartanella bacilliformis.
Speaker 1: Yeah, which is so fascinating to me. I didn't realize
Speaker 1: how recent it was that we even knew that like
Speaker 1: cat scratch fever or cat scratch disease and trench fever
Speaker 1: were caused by bacteria in the same genus, Like it's
Speaker 1: super recent.
Speaker 2: Yeah, it is really, and part of that recency, like
Speaker 2: we knew about some of those pathogens before, but this
Speaker 2: was just like merging with another genus and so it
Speaker 2: was sort of just like this restructuring of naming and grouping,
Speaker 2: and it does make looking at old papers more difficult
Speaker 2: and whatever, but it makes sense, and so here they
Speaker 2: all are together. Yeah. So anyway, even though we're only
Speaker 2: focusing on a few Bartnella species, there are a whole
Speaker 2: lot more where those came from with bartnella species infecting
Speaker 2: many other mammal species, but they didn't start out that way.
Speaker 2: This group, the Bartonellaca, is nested within the rhizobils, which
Speaker 2: is a group of nitrogen fixing soil bacteria.
Speaker 1: Oh fun.
Speaker 2: Yeah, And so researchers think that Bartonella probably started out
Speaker 2: as an environmental pathogen, and Bartonella bacteria are closely related
Speaker 2: to some plant pathogens and symbiants. And then that environmental
Speaker 2: pathogen turned into an insect gut symbiont, which then turned
Speaker 2: into a vertebrate pathogen.
Speaker 1: Oh my goodness. Yeah.
Speaker 2: And this last transition from insect gut symbiont to vertebrate
Speaker 2: pathogen is believed to have happened around the Cretaceous Paleogene
Speaker 2: boundary previously known as the KT boundary, just about sixty
Speaker 2: six million years ago, so like you know, when all
Speaker 2: the dinosaurs died in the big extinction event, and also
Speaker 2: around the time when there was like a big beginnings
Speaker 2: of mammal diversification as well, right right, Okay, And so
Speaker 2: what might have happened is that these arthropods that were
Speaker 2: hosting Bartonella began to evolve to be able to feed
Speaker 2: on the blood of these mammals, and then the Bartanella
Speaker 2: species inside them began to evolve to be able to
Speaker 2: infect those blood feeding arthropods, and then through that the
Speaker 2: blood of mammals.
Speaker 1: I love this so much erin, I had no idea,
Speaker 1: I know what.
Speaker 2: It is so cool. It is so cool. And so
Speaker 2: then after that it was like, all right, let's I
Speaker 2: found my vector, I found my mammal. I'm good to go.
Speaker 2: Let's just follow this evolutionary train right down the line.
Speaker 1: Yeah.
Speaker 2: And so that's when like a lot of these fairly
Speaker 2: tight vector host pathogen relationships began to form.
Speaker 1: Oh my gosh, that is so cool erin.
Speaker 2: Yeah, I really like that. There was a recent paper
Speaker 2: looking at the patterns of diversity within Bartonella that suggested
Speaker 2: that bats were among the first mammals to be infected,
Speaker 2: and that both bats and rodents were key in Bartonella
Speaker 2: both diversifying and spreading like millions of years ago, and
Speaker 2: then more recently though in terms of evolutionary history, there
Speaker 2: was another paper that talks about the role that humans
Speaker 2: have had in this like recent spread of Bartnella species
Speaker 2: through the movement of domestic or human associated animals, so
Speaker 2: like dogs, cats, cows, rats, etc. And that's fairly unsurprising.
Speaker 2: But what is cool is that we've seen not necessarily
Speaker 2: like we've seen some spillover events, and we've seen kind
Speaker 2: of like these not quite host switching events, but more
Speaker 2: like Bartanella species that are fairly host specific being able
Speaker 2: to infect other mammals that occupy the same ecological niche
Speaker 2: or geographic area. I mean like cats and people exactly.
Speaker 2: Oh okay, But Bartanella, I think is a cool group
Speaker 2: of bacteria because, in addition to telling us how different
Speaker 2: animals migrated and spread geographically, it's very long history and
Speaker 2: broad host and vector diversity. It makes it a great
Speaker 2: group to study things like vector host pathogen coevolution or
Speaker 2: the evolution of host specificity, or especially something that I
Speaker 2: was thinking a lot about during this episode was the
Speaker 2: trade offs between being a generalist pathogen and one that
Speaker 2: is specialist. Yeah. Yeah, because if you're a species of
Speaker 2: pathogenic bacteria, it may seem like on the surface that
Speaker 2: you know, if someone gave you the choice, do you
Speaker 2: want to be able to infect as many host species
Speaker 2: as possible, or do you want to just put all
Speaker 2: of your eggs in one basket. You would probably be like, eh,
Speaker 2: I think you know, I'm going to diversify here, that's
Speaker 2: going to be the best way to go. But that's
Speaker 2: not necessarily the case. We all know, like in life,
Speaker 2: you can't make everyone happy, and along those same lines,
Speaker 2: you can't infect everyone successfully either, because being well adapted
Speaker 2: to one species may make you more visible to the
Speaker 2: immune system of another. And there's a lot of other
Speaker 2: like trade offs that you can go into in terms
Speaker 2: of specificity versus generalist. And I've also seen it predicted,
Speaker 2: like overall that single host pathogens will be more successful
Speaker 2: than multi host pathogens. But it's also not necessarily as
Speaker 2: clear cut as that, especially in light of like widespread
Speaker 2: land use change and climate change, Like having the ability
Speaker 2: to exist in multiple different species might make you a
Speaker 2: little bit more resilient to change, for instance. So but anyway,
Speaker 2: and so this is why these these trade offs and
Speaker 2: the fact that there isn't a clear answer is why
Speaker 2: we do see some pathogens putting all their eggs in
Speaker 2: one host and others are spreading their eggs across many
Speaker 2: hosts literally and figuratively. Yeah, and so the same goes
Speaker 2: for Bartonella. Right, You'll find ones that are generalists, especially
Speaker 2: those whose vector species tend to be more generalist biers
Speaker 2: as well, like many of the rodent ectoparasites, and some
Speaker 2: that are very host specific, infecting only one mammal species,
Speaker 2: or just ones that are closely related, which brings me
Speaker 2: to Bartnella bacilliformis this Bartnella species, despite being the deadliest
Speaker 2: in humans by far and the first one to be
Speaker 2: described in general, not just on this podcast but in history,
Speaker 2: actually has quite a small history. And that kind of
Speaker 2: makes sense based on what you said. It's very localized,
Speaker 2: it's fairly rare occurrence wise. Yeah, and so let's go
Speaker 2: into the biggest outbreak that we know about to date.
Speaker 2: In the eighteen seventies, construction on a railway linking Lima
Speaker 2: and la Arroya began and a good number of the
Speaker 2: laborers that were working on the lines weren't actually from
Speaker 2: the area. They had come in from elsewhere, and they,
Speaker 2: during this construction began dying by the thousands, like whoah,
Speaker 2: absolutely astonishing numbers. It was estimated that more than seven
Speaker 2: thousand of the ten thousand workers building this railroad died
Speaker 2: of this unknown disease.
Speaker 1: Okay, that's just a straight up mortality rate of seventy percent.
Speaker 2: Yeah. Yeah, so that's I just was blown away. I
Speaker 2: was like, are you sure, Are you sure? Ye?
Speaker 1: Yeah, Oh my goodness.
Speaker 2: Yeah. And so, like you said, this disease sort of
Speaker 2: took this typical course, or I guess it's not so
Speaker 2: typical now that I've heard the biology. But of first
Speaker 2: this febrile hemolytic anemia, which was often the fatal part
Speaker 2: of it, and then if they survived, skin nodules. But
Speaker 2: it turns out that this unknown disease wasn't quite as
Speaker 2: unknown as people thought. Later, you know, looking back in
Speaker 2: history showed that there was some pottery from ancient Peru,
Speaker 2: like two thousand years years old that seems to depict
Speaker 2: some of the symptoms that the workers were having, like
Speaker 2: the skin nodules, and it was also probably described in
Speaker 2: some of the journals written during the Spanish invasion of
Speaker 2: South America. But this large outbreak, which gave rise to
Speaker 2: the name Roya fever, brought a lot of attention to
Speaker 2: the disease, and in eighteen eighty five, a Peruvian medical
Speaker 2: student named Danielle Carrion gave it its other name, Carrion's
Speaker 2: disease when he inoculated himself. I see you frowning already.
Speaker 2: You know what happens.
Speaker 1: I know, I usually am so good, but it was
Speaker 1: like in the front of every paper.
Speaker 2: Every paper. Yeah, that's just how it is. Yeah, well,
Speaker 2: we'll share with the group. Danielle Carrion inoculated himself with
Speaker 2: some I put juice from an infected skin lesion. I
Speaker 2: don't know if it was blood or pus or what juice,
Speaker 2: something from someone who had that second phase of the disease.
Speaker 2: And then he died of this febrile anemia, so like
Speaker 2: the first phase, his death through this very tragic experiment
Speaker 2: also showed that the two diseases were linked and likely
Speaker 2: caused by the same thing, which up until that point
Speaker 2: had not been known for sure. And then in nineteen
Speaker 2: oh nine, Alberto Barton hence Bartonella Barton, Yeah, a physician
Speaker 2: from Peru, published a paper describing bacteria in the blood
Speaker 2: cells of people with Arroya fever. But this on its
Speaker 2: own apparently wasn't good enough. This I found bacteria in
Speaker 2: the blood cells of people who had this disease. And
Speaker 2: also Danielle Carrion dying that wasn't good enough, and so
Speaker 2: a group of researchers from Harvard University went down in
Speaker 2: nineteen thirteen to conduct some experiments involving human quote volunteers
Speaker 2: oh uh huh, in which they basically repeated Carrion's fatal experiment,
Speaker 2: only the person didn't die, and so the researchers were like, eh,
Speaker 2: I mean, are they really related?
Speaker 1: Then?
Speaker 2: Like, are these really the same disease?
Speaker 1: Oh?
Speaker 2: My, yeah? And so eventually, however, it was accepted that
Speaker 2: both Arroya fever and Carrion's disease or verruga were caused
Speaker 2: by the same bacterial species. Still, though many questions remain.
Speaker 2: Like we talked about, right, we have no non human
Speaker 2: vertebrate reservoir. It historically was thought to be really restricted
Speaker 2: to just that like verruga zone, but as you mentioned,
Speaker 2: there have been outbreaks, like sporadic outbreaks of cases outside
Speaker 2: of that zone. So like, is it a new species,
Speaker 2: are there new strains, et cetera. We're going to need
Speaker 2: some updates on this if you have any, but.
Speaker 1: We'll see erin.
Speaker 2: Well, for now, let's just head to the next on
Speaker 2: the list.
Speaker 1: Okay, Oh, that was a good history Arin.
Speaker 2: Oh thanks.
Speaker 1: I really truly had had no clue what we were
Speaker 1: getting into.
Speaker 2: I know, I know, we'll take a we'll take a
Speaker 2: quick break before we get into the next one.
Speaker 1: I think that's a good plan. So our second species
Speaker 1: of Bartnella of the day is Bartanella quintana, and this
Speaker 1: causes the disease that many more people have probably heard of,
Speaker 1: and that is trench fever. So this particular species is
Speaker 1: transmitted not by sanfis, but by the human body lause
Speaker 1: pendiculous humanus corporus. You like that, I do. I love
Speaker 1: I mean, I don't love body lice, but I find
Speaker 1: lice to be really truly fascinating, talk about a species specific.
Speaker 1: There's a body louse and a head louse, and they
Speaker 1: are different.
Speaker 2: I was I did not know that until this episode.
Speaker 1: Yeah, uh huh. So this is transmitted by the body louse,
Speaker 1: not the head louse, so don't freak out when your
Speaker 1: kid brings home lice. They're different.
Speaker 2: Although it can be transmitted through head lice.
Speaker 1: Yeah, it probably can canmute.
Speaker 2: Anyways, but it's rare. That's not what usually happens.
Speaker 1: Oh, but like with Bartonella bacilliformis, there is no known
Speaker 1: natural animal reservoir for Bartnella quintana. So as far as
Speaker 1: we can tell, this is a human specific disease, which
Speaker 1: makes sense if it's being transmitted by the human body
Speaker 1: lous and like Auroya fever, the acute stage of carrion disease,
Speaker 1: trench fever is a bloodstream infection. So this is a
Speaker 1: disease that happens when these bacteria replicate and proliferate inside
Speaker 1: of our red blood cells. The symptoms, though, look a
Speaker 1: little bit different. The symptoms are a periodic relapsing fever
Speaker 1: most often, and this can range from fairly mild to
Speaker 1: pretty severe in terms of symptoms, but in general, the
Speaker 1: onset is sudden and starts about a week after infection,
Speaker 1: although the incubation period can be up to twenty five days,
Speaker 1: and starts with a fever that tends to last classically
Speaker 1: five days, but I saw some papers that said like
Speaker 1: one to three days. So everything in medicine that's called
Speaker 1: classic is probably not one hundred percent true. I'm going
Speaker 1: to make someone angry, but that's the case. But this
Speaker 1: fever is associated with severe headache, often dizziness, and for
Speaker 1: some reason that Aaron do not ask me why shin pain?
Speaker 2: Okay, So I do have a question about shins.
Speaker 1: Though, Okay, Aerin, what's your question?
Speaker 2: That is in the quote unquote classic description of the disease,
Speaker 2: which you know spoilers was first described in World War One,
Speaker 2: and so I was wondering if it was something about
Speaker 2: the conditions of the trenches or what it was like
Speaker 2: to be in the trenches, like do people who have
Speaker 2: trench fever today still describe severe shin pain?
Speaker 1: Good question, that's a very good question. In most of
Speaker 1: the descriptions that I I read, they likely go off
Speaker 1: of some of those more classic descriptions rather than I
Speaker 1: didn't read a lot of individual case reports to know
Speaker 1: what specific people's symptoms were today. But other papers that
Speaker 1: I read said more generally bone pain so and joint
Speaker 1: pain is also really common, which makes sense because you
Speaker 1: have blood cells. That's where your blood cells are coming from.
Speaker 1: So it does make sense that there would be bone pain.
Speaker 1: But maybe it's not always specific to your shins, and
Speaker 1: maybe in World War One it was something to do
Speaker 1: with that rather than specifically just this. Yeah, okay, in
Speaker 1: a good question. So, in general, this is a disease
Speaker 1: where these fever episodes often recur, and when they recur,
Speaker 1: it might be every four to six days or so.
Speaker 1: And so, because some people say the fever last five
Speaker 1: days or sometimes these episodes recur every five ish days,
Speaker 1: trench fever is often sometimes called five day fever or
Speaker 1: quinton fever. Right side note. You know, it's interesting arin
Speaker 1: trench fever recurrent febrile illness where bacteria is infecting your
Speaker 1: red blood cells. Malaria recurrent febrile illness where parasites are
Speaker 1: infecting your red blood cells.
Speaker 2: Yeah, yeah, and only so this is what that's what
Speaker 2: they noticed during World War One, and they tried to
Speaker 2: treat them with quinine, but that didn't work avail.
Speaker 1: Yeah. I just thought that was an interesting little side note.
Speaker 2: Which also brings me to another question. Okay, why is
Speaker 2: it relapsing?
Speaker 1: It's a really good question. There's a number of There's
Speaker 1: another disease that is lousborne relapsing fever that's caused by
Speaker 1: a different species of bacteria. It's a Burellia species, right.
Speaker 1: I'm not entirely sure why. And and this comes back
Speaker 1: to the fact that we don't have good animal models
Speaker 1: for these illnesses. So the specifics of a lot of
Speaker 1: this path of physiology, I just don't have answers to huh. Yeah.
Speaker 1: But unlike Bartnella bacilliformis the cause of Carrion's disease trench fever,
Speaker 1: Bartnella quintana does not cause a severe hemolytic anemia, so
Speaker 1: it's generally self limited, doesn't have a huge mortality rate.
Speaker 1: Certainly people have died from it, but it can also
Speaker 1: cause a chronic infection like we've seen with bacilliformis. It
Speaker 1: can also cause an asymptomatic infection entirely, and it can
Speaker 1: go on to cause some pretty severe infections, much more
Speaker 1: severe than trench fever. So there's a whole nother disease
Speaker 1: called bacilliary angiomatosis.
Speaker 2: H huh.
Speaker 1: Yeah. Vacilliary just refers to involving a rod shaped bacterium,
Speaker 1: so that's the bacterium in this case. And an angioma
Speaker 1: is an abnormal growth either on the skin or internal
Speaker 1: organs that is due to the formation of new blood
Speaker 1: vessels or the dilation of existing ones. Does that sound familiar, Uh.
Speaker 2: Huh, it certainly does. Yeah.
Speaker 1: So bacilliary angiomatosis was discovered in HIV positive patients. So primarily,
Speaker 1: it's a disease of immunal compromise, and it has been
Speaker 1: found to be caused often by Bartnella quintana and other
Speaker 1: species of Bartonella. Uh huh oh yeah, we'll get to
Speaker 1: you a little bit more later. So what is it exactly?
Speaker 1: What does it look like? It's lesions, not so dissimilar
Speaker 1: to Vruga peruana, but dissimilar enough that bacilliary angiomatosis is
Speaker 1: a very severe illness. These lesions are most often and
Speaker 1: most obviously on the skin, but unlike with Viruga peruana,
Speaker 1: they're not limited to the skin. The damaging part is
Speaker 1: that these same lesions, these like tumors made from blood vessels,
Speaker 1: essentially can be found on any other internal organs. And
Speaker 1: you can imagine these are blood vessels, they can bleed
Speaker 1: quite intensely, and so that bleeding itself can be life
Speaker 1: threatening as well as just having these growths that can
Speaker 1: get large on other internal organs. So basilier androomatosis is
Speaker 1: a much more severe disease that can also be fatal.
Speaker 2: How often does that occur? I guess, like, if you
Speaker 2: are immunal compromised, how often does it occur?
Speaker 1: It's a good question. I don't have solid numbers on it.
Speaker 1: The numbers that I saw in people living with HIV.
Speaker 1: The prevalence of Bartnella associated infection is still quite low,
Speaker 1: like one in a thousand in some studies in Germany
Speaker 1: and Spain. Okay, yeah, so it's still a very very
Speaker 1: rare disease. It's not only associated with HIV. It's also
Speaker 1: has been found in people who are organ transplant recipients
Speaker 1: and other cases of immuno compromise. In rare cases, it
Speaker 1: has happened as well in people who are otherwise immuno competent.
Speaker 1: Why great question, right, Yeah, we don't know. And then finally,
Speaker 1: because that's not quite all, Bartonella quintana has also come
Speaker 1: very recently, within the last couple of decades to be
Speaker 1: recognized as an important cause of what used to be
Speaker 1: called culture negative endocarditis. Endocarditis we've talked about a lot.
Speaker 1: This is an infection of the heart tissue itself, which
Speaker 1: again unsurprising considering this bacteria likes our endothelial cells, and
Speaker 1: so endocarditis associated with Bartonella, as well as trench fever
Speaker 1: have both become important causes of disease today, not just
Speaker 1: in world wars, but today among people experiencing homelessness, and
Speaker 1: so that's the majority of where we see Bartnella quintana
Speaker 1: infections today.
Speaker 2: I actually have a bit of trivia too about endocarditis
Speaker 2: that I didn't include in like my little history section.
Speaker 1: Tell me it.
Speaker 2: So, during World War One there was a condition that
Speaker 2: was called either disorderly action of the heart or soldier's heart,
Speaker 2: which was a variety of shell shock. Like it was
Speaker 2: just sort of this no one knew what was causing it,
Speaker 2: and one paper I read suggested that at least some
Speaker 2: of these cases might have been caused by this endocarditis
Speaker 2: caused by quintana.
Speaker 1: Fascinating. Oh that's really interesting. Yeah, Aaron, tell me more
Speaker 1: interesting things. What's up with this particular species of Bartnella?
Speaker 1: Where did trench fever come from?
Speaker 2: I'll get right into it. Okay, this is fun.
Speaker 1: Yeah, I'm really learning a lot.
Speaker 2: Yeah, Okay. On July twenty eighth, nineteen fourteen, World War
Speaker 2: One began, and this episode I looked it up. I'm
Speaker 2: pretty sure will actually be released on July twenty seventh,
Speaker 2: and so that'll be the day before the one hundred
Speaker 2: and seventh anniversary of the start of the Great War.
Speaker 1: Wow, Yeah, tinally totally planned.
Speaker 2: Yeah. Sure. By September of nineteen fourteen, trench warfare had
Speaker 2: begun on the Western Front, starting with a battle in France.
Speaker 2: And when I say trench warfare had begun, I mean
Speaker 2: it had begun. Within a few months of this battle,
Speaker 2: four thousand miles of trenches were dug and maintained from
Speaker 2: the English Channel to Switzerland. WHOA trench warfare was brutal,
Speaker 2: it was deadly, it was horrific. And in these trenches
Speaker 2: soldiers would live, they would fight, they would die, and
Speaker 2: many of them would get infected with trench fever. By
Speaker 2: June nineteen fifteen, an unusual febrile infection was running rampant
Speaker 2: through the troops that spent a lot of the time
Speaker 2: in the trenches, and it drew enough attention to end
Speaker 2: up in a report by British medical officer Major John
Speaker 2: Graham quote, a private from an infantry regiment was admitted
Speaker 2: to a casualty clearing station suffering from a febrile illness
Speaker 2: of three days duration, headache, dizziness, severe lumbago, a feeling
Speaker 2: of stiffness down the front of the thighs and severe
Speaker 2: pains in the legs referred chiefly to the shins. I
Speaker 2: have been receiving cases in considerable numbers, presenting clinical features
Speaker 2: which do not differ from those given above. And this
Speaker 2: was the first description of what would become known as
Speaker 2: trench fever, an illness that didn't often kill you, like
Speaker 2: rarely killed you, but it would take a lot out
Speaker 2: of you, leaving you as a soldier unable to fight
Speaker 2: for up to two months at a time.
Speaker 1: Wow, that's a long time.
Speaker 2: It is a long time. Yeah. After this first report,
Speaker 2: military physicians all over began recognizing it in the troops
Speaker 2: that they treated, and after first being seen in British soldiers,
Speaker 2: it popped up in French troops, then in Greece, Italy
Speaker 2: and all across the Eastern Front. And it wasn't just limited,
Speaker 2: of course, to the Allied forces. Regardless of where you
Speaker 2: were from or who you were fighting for, if you
Speaker 2: found yourself in the trenches, you were likely to find
Speaker 2: yourself with trench fever at some point, or at least
Speaker 2: you're the person standing next to you or digging the
Speaker 2: trench next to you was likely to have trench fever. Yeah.
Speaker 2: And while some soldiers viewed trench fever as a welcome
Speaker 2: relief because it took you off the front lines for
Speaker 2: like sixty to seventy days to recover. And actually one
Speaker 2: paper pointed out that it probably saved a lot of
Speaker 2: lives that way.
Speaker 1: Yeah, that makes sense.
Speaker 2: Yeah, those higher up in the armed forces sought as
Speaker 2: a massive problem in reducing like the sheer numbers of
Speaker 2: available troops. This was like a lot of this was
Speaker 2: just a numbers game, and it certainly did reduce these numbers.
Speaker 2: Official records were not kept on the overall incidents of
Speaker 2: the disease, but I did see one estimate of about
Speaker 2: one million cases among the Allied troops alone, which is
Speaker 2: quite a lot. Yeah, there were actually a lot of
Speaker 2: famous people with trench fever.
Speaker 1: Oh, I feel like we haven't done famous people with
Speaker 1: this disease in a while.
Speaker 2: We really haven't. And this there's a really funny These
Speaker 2: are all. I'm sure there are more that are out there,
Speaker 2: but I just came across an article that mentioned the
Speaker 2: names AA Milne, so Winnie the pooh Oh, the pooh Okay, J. R. R. Tolkien,
Speaker 2: oh uh huh, and C. S. Lewis. Oh Wow, all
Speaker 2: got trench fever. I think Milne was actually taken off
Speaker 2: of the lines and highly because of trench fever.
Speaker 1: Oh my gosh. And yeah, we can probably thank trench
Speaker 1: fever for Whinney the poo.
Speaker 2: And Lord of the rings and Lord of the rings
Speaker 2: and the language.
Speaker 1: We know things.
Speaker 2: Yeah, trench fever caused one fifth to one third of
Speaker 2: all illnesses in the British army and one fifth in
Speaker 2: the Central Powers.
Speaker 1: Wow a lot.
Speaker 2: And even once the war was over and the disease
Speaker 2: had run its long course, many people were still impacted
Speaker 2: by it. For instance, six thousand men in Britain attributed
Speaker 2: their war disability to trench fever in nineteen twenty, so,
Speaker 2: a couple of years after the war ended. And while
Speaker 2: trench fever could not hold a candle to the morbidity
Speaker 2: and mortality caused by influenza or typhoid or cholera or
Speaker 2: dysentery or all of the other diseases that were flourishing
Speaker 2: under these war conditions, the sheer number of soldiers it
Speaker 2: took out of commission made it somewhat of a priority
Speaker 2: to figure out what was causing this disease and how
Speaker 2: it was being transmitted.
Speaker 1: That's very interesting.
Speaker 2: Preliminary research had already put forth body lice as the
Speaker 2: main suspect for transmission, that disease could be transmitted through
Speaker 2: the inoculation of blood from an infected person, but not
Speaker 2: plasma alone. Infections continued to occur throughout the winter, which
Speaker 2: ruled out flies or midges or mosquitoes which wouldn't be
Speaker 2: able to overwinter as well as the body louse, and
Speaker 2: units that had more body lice had more trench fever
Speaker 2: or unexplained pyrexia, which is what it was often put
Speaker 2: down as before like trench fever became a more popular term, okay,
Speaker 2: and efforts to control lice had led in a few
Speaker 2: instances to a reduction in the incidence of this pyrexia
Speaker 2: of an unknown origin. And by the way, control efforts
Speaker 2: were like next to impossible. There would be like a
Speaker 2: steam disinfestor or something that it was like rarely operational.
Speaker 2: If you were in the trenches, you were there dug
Speaker 2: in for a long time, and so it was like, okay,
Speaker 2: the goal was to shower at least once every two weeks,
Speaker 2: like that was the standard, and that is just not
Speaker 2: frequent enough to completely rid yourself of lice. Yeah, and
Speaker 2: so there was a study in nineteen fifteen that found
Speaker 2: that ninety five percent of soldiers were infested with body lice,
Speaker 2: with an average of twenty LIFs per soldier, with five
Speaker 2: percent of soldiers having one hundred to three hundred lice each.
Speaker 1: Oh my god.
Speaker 2: Can you imagine how itchy?
Speaker 1: No, that sounds terrible.
Speaker 2: Yes. And so despite this evidence, though in support of
Speaker 2: the body louse, there was still debate over the root
Speaker 2: of transmission, and so a couple of research commissions were
Speaker 2: set up by the British and the Americans in a
Speaker 2: very bureaucratic fashion, which meant that the studies themselves didn't
Speaker 2: start until closer to the end of the war, and
Speaker 2: the results would be published too late to do much
Speaker 2: to stop the spread of the disease. But still the
Speaker 2: commissions made a few important and in my opinion like
Speaker 2: impressive observations during a time when there were a lot
Speaker 2: of other deadly things going around, and when medical and
Speaker 2: microbiological knowledge and technology isn't anywhere close to what it
Speaker 2: is today. I should also note that this was done
Speaker 2: through the use of human volunteers quote unquote, because, like
Speaker 2: you mentioned, human body lice don't feed on non primates
Speaker 2: and lab animals aren't susceptible to trench fever, So these
Speaker 2: studies found that it was indeed the body louse responsible
Speaker 2: for transmission, or more accurately, louse poop. Yeah, it wasn't
Speaker 2: carried in the serum, but in the blood itself. All
Speaker 2: it took was one louse who became infectious five days
Speaker 2: after feeding on an infected person and could remain infectious
Speaker 2: for at least four months. Wow, even though I don't
Speaker 2: know how long, I thought the average lifespan of a
Speaker 2: body louse was like one month.
Speaker 1: That was I was just about to ask you, how
Speaker 1: long does a body louse live? I don't know the
Speaker 1: answer to that.
Speaker 2: I thought I saw in one paper it was comparing
Speaker 2: the different life spans of the vectors of different Bartonella species,
Speaker 2: and I thought a body louse was pretty short. But
Speaker 2: maybe maybe if you keep them, if you maintain them,
Speaker 2: maybe the location. Yeah, four months is like your pet louse.
Speaker 2: One month is like, yeah.
Speaker 1: Your trench louse.
Speaker 2: Yeah. And they also found that a person with trench
Speaker 2: fever could infect lice for at least four hundred and
Speaker 2: forty three days after first showing signs of illness whoa yeah,
Speaker 2: and that the pathogen, which was still unknown, did not
Speaker 2: seem to be able to be transmitted vertically from parent
Speaker 2: louse to offspring I.
Speaker 1: Mean four hundred and forty three days. I feel like
Speaker 1: that explains why the Commission took so long to get
Speaker 1: these results published. They were just like still infectious, Still
Speaker 1: infectious for sure.
Speaker 2: Yeah. They're like, well we're still going like a least
Speaker 2: still forty three days. Yeah. And so while this info
Speaker 2: would have been, you know, nice to know during World
Speaker 2: War One, at least it would be useful in the
Speaker 2: next war, not that people knew there was going to
Speaker 2: be a next war, but World War two didn't have
Speaker 2: as much trench warfare as World War One. And also
Speaker 2: the use of DDT had substantially reduced the infestation rates
Speaker 2: with lice, and so it just wasn't much of a
Speaker 2: problem at all trench fever, Okay. And even though a
Speaker 2: lot was known about the disease and its transmission, the
Speaker 2: causative agent of trench fever was still unknown and wouldn't
Speaker 2: be described until nineteen sixty one.
Speaker 1: Wow, Yeah by J. W.
Speaker 2: Vincent, which I think gave his last name to another
Speaker 2: species of Bartnella Vinsonia. Maybe I think that infects dogs.
Speaker 1: I might be wrong, and it's familiar.
Speaker 2: Yeah, who initially named it Ricketzia quintana. So quintana, like
Speaker 2: you mentioned, is from five day fever, But later studies
Speaker 2: showed that it wasn't a Ricketsia even though it seemed
Speaker 2: like one, because it could be cultured, meaning it wasn't
Speaker 2: obligately intracellular, and so it was put in the genus Rochelimea,
Speaker 2: which was changed to Bartonella when the two genera were
Speaker 2: merged like I mentioned earlier in nineteen ninety three, And
Speaker 2: once the organism could be cultured, different antibiotics could be
Speaker 2: tested to see which were effective, and sporadic outbreaks became
Speaker 2: more manageable. But the bacterium didn't disappear just because there
Speaker 2: were no just because there was no more trench warfare.
Speaker 2: Starting in the nineteen nineties, trench fever has made a
Speaker 2: substantial comeback, as I'm sure that you will talk about him,
Speaker 2: and already have touched on a bit. But before we
Speaker 2: get to that, I need to go back a little
Speaker 2: bit or a lot bit, because I started trench fever
Speaker 2: in kind of the middle of the story. Although the
Speaker 2: conditions during World War One trench warfare were pretty perfect
Speaker 2: for the proliferation of Bartnella quintana. The relationship between the
Speaker 2: bacterium and humans goes way back.
Speaker 1: Okay, we already.
Speaker 2: Know that Bartnella in general evolved with their vertebrate hosts,
Speaker 2: but in the case of Bartnella quintana, we also have
Speaker 2: hard proof of this. Researchers found Bartnella quintana DNA in
Speaker 2: the dental pulp of someone who died four thousand years
Speaker 2: ago in southeastern France. Very cool dental pulp. Dental pathogen
Speaker 2: DNA is the best.
Speaker 1: It is almost as good as copper lights.
Speaker 2: It Oh God, do I love a copper light? Yeah.
Speaker 2: And then there was also a study showing evidence of
Speaker 2: infection in Napoleonic soldiers from around eighteen twelve, and those
Speaker 2: soldiers there was actually a twenty percent prevalence with this pathogen.
Speaker 1: Man, so four thousand years minimum.
Speaker 2: Uh huh, oh, it's gonna get even cooler. Stop how Okay.
Speaker 2: So there's been other archaeological research that has like found
Speaker 2: evidence of infection all across Europe and in some other places.
Speaker 2: And so the fact that like it was first described
Speaker 2: during World War One was probably just because of like
Speaker 2: the conditions right previously, it was probably grouped in with
Speaker 2: just fever, like general fever in the pre germ theory days.
Speaker 2: And actually one paper made a note that like this
Speaker 2: lack of distinction among fevers may have been why in
Speaker 2: some years mortality from fever was really low. So like
Speaker 2: if there was a lot of trench fever going around.
Speaker 1: Then everyone had a fever, but nobody was dying. Yeah, fascinating, Okay.
Speaker 2: Okay, So Bartonella Quintana and humans have been cozy with
Speaker 2: one another for probably as long as the human body
Speaker 2: louse has been with humans. But how long is that?
Speaker 1: Boo tell me?
Speaker 2: Apparently around seventy two thousand years, which is when it
Speaker 2: diverged from the head louse. And that's also around the
Speaker 2: same time Aaron that the use of clothing increased and
Speaker 2: as humans began their out of Africa migration, so it
Speaker 2: kind of spread with humans as humans moved and started
Speaker 2: wearing clothing. Oh m g isn't that very cool?
Speaker 1: Dude, lice? I'm telling you, I very cool.
Speaker 2: So Bartnella became specialized on humans and the human body
Speaker 2: louse for the most part. More recently, though it has
Speaker 2: been detected that Bartnella quintana in a couple of monkey species,
Speaker 2: including the caqs. Yeah, and researchers were actually able to
Speaker 2: inoculate macaques and produced chronic bacteremia. Okay, so it's unclear
Speaker 2: how prevalent natural infection is with this bacterial species in
Speaker 2: different species of monkeys, but it's possible that the bacteria
Speaker 2: spilled over into humans from non human primates, either more
Speaker 2: recently or a long time ago. It seems like it
Speaker 2: would be a long time ago. I don't know for sure,
Speaker 2: but regardless of how exactly Quintana came to be, this
Speaker 2: pretty specialist bacterial species is a contrast to our next
Speaker 2: and last Bartanella species, Bartonella Hensley.
Speaker 1: Oh, I'm excited about this one. Do you do we
Speaker 1: need a break first or should we just just go there?
Speaker 2: I think let's take a break and then wrap it up.
Speaker 1: Great, okay, quick break. Okay, So now it's not where
Speaker 1: we go off the rails, but like we are, I
Speaker 1: think we're on a different train on the same rails.
Speaker 1: Oh yeah right, yeah.
Speaker 2: Okay, we've hopped in a new car.
Speaker 1: Definitely a new car. Definitely, Yeah, new car. So Bartonella
Speaker 1: hensley aka cat scratch disease. So this is a species
Speaker 1: of Bartnella that commonly infects cats, feral and domestic, and
Speaker 1: between cats it seems to be transmitted by the cat
Speaker 1: flea tino Cephalides felis, which makes sense based on what
Speaker 1: we know so far about Bartonella. Right, these are tend
Speaker 1: to be vector born species. Mm hmm. But humans, for
Speaker 1: the most part, become infected from contact with a cat directly,
Speaker 1: specifically from scratches or bites. Wait a second, uh huh,
Speaker 1: but how in many parts of the world, like fifty
Speaker 1: percent of cats have evidence of infection with Bartnella hensley
Speaker 1: currently past infection. Sure, and just like Bartnella species that
Speaker 1: we've talked about that are specific to humans can maintain
Speaker 1: chronic bacteremia without any symptoms of disease. Potentially, that's what
Speaker 1: happens in cats. So in cats, they get infected from
Speaker 1: fleas like cats have fleas, and in general they don't
Speaker 1: have any symptoms of disease, but they can maintain a
Speaker 1: chronic state of having these bacteria in their bloodstream that
Speaker 1: can then somehow arin be present in their claws or
Speaker 1: in their mouth.
Speaker 2: Yeah, that's that's the part that I'm struggling with.
Speaker 1: I mean, I don't have a great answer to it.
Speaker 2: Is it in their saliva?
Speaker 1: I think it maybe perhaps it could be in saliva,
Speaker 1: but also like cat's gums bleed a lot. Have you
Speaker 1: ever looked inside a cat's mouth?
Speaker 2: I mean, but I just the claws and the mouth
Speaker 2: like it. Cat fleas don't bite humans.
Speaker 1: No, in general, and that is not how people get infected.
Speaker 1: It is possible, like it is physically possible to get
Speaker 1: infected through a vector with Bartonella hensley, but in general,
Speaker 1: people get infected from cat scratches and bites.
Speaker 2: I need more info on this, struggling.
Speaker 1: Oh that's all I got for you, Aaron. I mean,
Speaker 1: that's not all I got for the biology.
Speaker 2: But I was like, this is that is a really
Speaker 2: short one? Wow? Yeah?
Speaker 1: No, yeah, I mean it is very interesting, right because
Speaker 1: in general, it's a bacteria that's found inside of cells,
Speaker 1: mostly in red blood cells and endothelial cells, but it
Speaker 1: finds its way into the saliva and claw of cats.
Speaker 2: I'm baffled.
Speaker 1: I mean, maybe it's like when cats scratch or bite people,
Speaker 1: maybe that there tends to be you know, action more
Speaker 1: than just a little little kitty scratch.
Speaker 2: I'm gonna think about this as I'm trying to sleep tonight.
Speaker 1: I don't have a great nothing that I read talked
Speaker 1: about it not weird, that's so strange, so off the top.
Speaker 1: Clearly this is a weird one, right, different than other
Speaker 1: species we've covered. It's also a very different illness that
Speaker 1: is cat scratch disease. Okay. In general, it is fairly
Speaker 1: mild and self limited. It most often occurs in kids,
Speaker 1: but that's probably more likely due to exposure than susceptibility.
Speaker 1: It also can happen in older people as well, and
Speaker 1: anyone any age. And it looks like this. First, about
Speaker 1: three to ten days after a bite or scratch, you'll
Speaker 1: get a little lesion on the skin, usually quite close
Speaker 1: to the wound, just like a pushtual or maybe a
Speaker 1: little scab. This will crust over, and then usually over
Speaker 1: the course of a few weeks, you'll start to develop
Speaker 1: swollen lymph nodes, just a few, like one, two, et cetera,
Speaker 1: just on one side, the side near wherever the bite was.
Speaker 1: So if you got bit on your arm, then maybe
Speaker 1: the lymph nodes in your armpits. If you got bit
Speaker 1: on the cheek, maybe under your neck, behind your ear, wherever.
Speaker 1: And then maybe around that time, as your lymph nodes
Speaker 1: start to swell, you might have some mild symptoms like
Speaker 1: a fever or body aches or joint aches, just feeling cruddy.
Speaker 1: But really it's just these swollen lymph nodes, and they
Speaker 1: can stay swollen for quite some time. It can often
Speaker 1: take about seven weeks or more before they completely resolve.
Speaker 1: In some cases, like twenty percent of the time, they
Speaker 1: can persist for six months to two years. Whoa, oh yeah,
Speaker 1: and about ten percent of the time this swollen node
Speaker 1: will kind of burst out to the surface a bit,
Speaker 1: so you'll have like puss draining from it.
Speaker 2: But bikes, that sounds uncomfortable.
Speaker 1: Yeah, it's definitely uncomfortable, but that's rare. That's like ten
Speaker 1: percent or less. Usually it's some swollen lymph nodes self
Speaker 1: limiting and it goes away. So it's already a lot
Speaker 1: of weird things. In humans, this bacteria for some reason
Speaker 1: is infecting tissues in our lymph nodes rather than directly
Speaker 1: infecting our red blood cells.
Speaker 2: Where does it go?
Speaker 1: In cats, it goes into their red blood cells, but
Speaker 1: it doesn't cause disease and it doesn't cause any of
Speaker 1: the angioproliferative or the like skin disorders that we've seen
Speaker 1: with other Bartanella. That doesn't happen in cats. Usually they
Speaker 1: have no symptoms whatsoever.
Speaker 2: And it doesn't go into their lymph nodes.
Speaker 1: Not enough to cause them to swell. Okay, But it
Speaker 1: gets even weirder because in people who are immunocompromised, Bartnella
Speaker 1: Hensley is a very important cause of bacilliary angiomatosis, that
Speaker 1: disorder that we already talked about caused by Bartnella Quintana, right,
Speaker 1: and with Bartnella Hensley it can actually be even worse
Speaker 1: because these vascular tumors can be found on the liver.
Speaker 1: This is sometimes called an entirely different disease pelosis hepatis
Speaker 1: or bacilliary pelosis. That just means these tumors on your liver. Okay,
Speaker 1: And in both immunocompromised as well as immunocompetent people, very rarely,
Speaker 1: Bartnella Hensley can infect the nervous system and cause things
Speaker 1: like encephalopathy. There's a few cases of it causing like
Speaker 1: neuropsychiatric disorders potential. It's very bizarre.
Speaker 2: I this yeah, This one is definitely the weirdest.
Speaker 1: It is definitely the weirdest, and it's a zoonotic disease.
Speaker 2: Right.
Speaker 1: This is a species of bacteria that's closely associated with cats.
Speaker 1: It can also infect dogs, and in dogs it can
Speaker 1: actually cause endocarditis.
Speaker 2: Okay, but in cats it.
Speaker 1: Doesn't tend to cause any disease. None of these symptoms
Speaker 1: seem to happen whatsoever. And so all of this is
Speaker 1: to say that that's part of why we really don't
Speaker 1: understand a lot about the pathogenesis of Bartonella in general,
Speaker 1: this species or otherwise, because even here where we have
Speaker 1: a zoonotic species, you would think, well, at least we
Speaker 1: have an animal model. It's in cats. Fifty percent of
Speaker 1: cats are infected, but they don't manifest the same disease,
Speaker 1: so we can't study this human disease in cats or
Speaker 1: in other animals.
Speaker 2: Bartinella is like this is tip of the iceberg type
Speaker 2: thing where you're like, oh, I see what's on the surface.
Speaker 2: This is going to be very straightforward, and then it's
Speaker 2: like just kidding.
Speaker 1: Right, we severely underestimated them. Yeah, So for the last
Speaker 1: and final time, Aaron, can you tell me how we
Speaker 1: got here? Where Bartnella Hensley came from, Like, what's up
Speaker 1: with cat scratch disease?
Speaker 2: I'll just dive right in yet again, please. So I
Speaker 2: was trying to think of, like, what is the take
Speaker 2: home for all of us? Is there any sort of
Speaker 2: like unifying theme, And the only thing that I could
Speaker 2: really think of was that the growth of knowledge doesn't
Speaker 2: happen in a predictable way, or rarely happens in a
Speaker 2: predictable way, and that we may only recognize how things
Speaker 2: are connected in retrospect and like rarely, if ever, at
Speaker 2: the time when we're examining them. And I think this
Speaker 2: can definitely be said for the two Bartnellas We've already
Speaker 2: talked about Basilliformis and Quintana, but I think it's especially
Speaker 2: true for our last Barnella Hensley. So not only did
Speaker 2: it take until nineteen ninety three for this bacterium to
Speaker 2: be put in the Bartonella genus along with Quintana during
Speaker 2: that reshuffle thing or merge, it was only ten years
Speaker 2: before that that it was seen for the first time.
Speaker 2: Despite the disease itself, cat scratch fever, being known for
Speaker 2: one hundred years and clinically described for fifty years.
Speaker 1: Goodness gracious.
Speaker 2: Yeah, So let's get into it. First off, there is
Speaker 2: most definitely evidence of ancient infection with this bacterium. Again
Speaker 2: using dental pole researchers found Bartnella hensley DNA in eight
Speaker 2: hundred year old French cats from the thirteenth, fourteenth, and
Speaker 2: sixteenth centuries, and it's likely that cats have been infected
Speaker 2: with the bacterium since cats have been cats, or at
Speaker 2: least since the cat flea began biting cats, and since
Speaker 2: Bartonella hensley is also able to infect humans, it seems
Speaker 2: also likely that humans have probably been prey to this
Speaker 2: pathogen since humans and cats began associating with one another,
Speaker 2: which was around seventy five hundred BCE. But the earliest
Speaker 2: description we have of anything resembling cat scratch disease or
Speaker 2: cat scratch fever is from eighteen ninety eight, when a
Speaker 2: physician described a condition similar to and thought to be
Speaker 2: in retrospect of course, cat scratch fever in the context
Speaker 2: of oculoglandular syndrome. That's all. I don't really know, and
Speaker 2: the disease got its official clinical description only in nineteen
Speaker 2: fifty by Robert Debray, professor of pediatrics at the University
Speaker 2: of Paris. Doctor Debray was no stranger to this disease,
Speaker 2: having treated a ten year old boy in nineteen thirty
Speaker 2: one who had a cold fistillated adnitis that healed quite
Speaker 2: nicely on its own, and the doctor, though, was struck
Speaker 2: in particular by the severe and numerous cat scratches on
Speaker 2: the same hand as the same side as the adonitis.
Speaker 1: Oh gosh, I know.
Speaker 2: The boy's mother said that although her son had been
Speaker 2: told not to play with the cats, she found him
Speaker 2: like in his room with a bunch of the kittens
Speaker 2: and they were all hanging out together and just couldn't resist,
Speaker 2: which I think is really cute.
Speaker 1: I hope he had fun. I hope it was worth it.
Speaker 2: Yeah. Yeah, it healed nicely, Yeah, exactly.
Speaker 1: So.
Speaker 2: Initially doctor Debray was convinced that this was like a
Speaker 2: form of tuberculosis, but he was unable to isolate the
Speaker 2: tuberculosis bacterium, so then he figured, Okay, it must be
Speaker 2: some sort of bacterial infection from the cats. But again,
Speaker 2: none of these bacterial assays or investigations turned up anything.
Speaker 2: The wound healed, the kid recovered that the case stuck
Speaker 2: out in the doctor's mind. Over the next years, doctor
Speaker 2: Debray saw additional cases of adnopathy that cleared up on
Speaker 2: their own, all of them with cat associations, and he
Speaker 2: took to calling it cat scratch disease. But despite a
Speaker 2: regular influx of cases, he was never able to find
Speaker 2: or isolate a causative agent. And Debray wasn't the only
Speaker 2: one to recognize this strange illness. Lee Fouchet, a professor
Speaker 2: of microbiology at the University of Cincinnati in Ohio, had
Speaker 2: also noticed it, and when Debray visited Cincinnati in nineteen
Speaker 2: forty seven for I Believe a conference, they struck up
Speaker 2: a conversation when they realized they both had a special
Speaker 2: interest in and experience dealing with this cat associated illness.
Speaker 2: How fun, I know, right, And they had even come
Speaker 2: up with baby basically the same name for it, so
Speaker 2: Debray called it cat scratch disease while Fauchet called it
Speaker 2: cat scratch fever. Debray was super excited to find another
Speaker 2: person interested in it, and especially so when he learned
Speaker 2: that Fauchet had developed a diagnostic antigen test, and he suggested, like, oh,
Speaker 2: you know, let's put our minds together. We'll publish two
Speaker 2: articles about this disease. Yours will be about the diagnostic test,
Speaker 2: mine will be about the clinical disease. But Fauchet was like, no, no,
Speaker 2: I'm not a clinician or pediatrician. I'm a bacteriologist and
Speaker 2: a virologist, and I won't publish anything until I find
Speaker 2: the causative agent. So Debray was like, oh, man, like bummer,
Speaker 2: the stinks. And it took him a few years to
Speaker 2: get up the nerve to publish anything on cat scratch disease,
Speaker 2: which he finally did in January of nineteen fifty. The
Speaker 2: publication of his description got the wheels turning for other people,
Speaker 2: and additional work on the disease continued, with the more
Speaker 2: antigen diagnostic tests being developed and experiments infecting cats and humans.
Speaker 2: But like Bartnella Quintana, much of the progress had to
Speaker 2: do with describing the disease itself rather than isolating the
Speaker 2: causative agent. But that changed when in nineteen eighty three,
Speaker 2: the Bacillis was discovered in lymph nodes of patients with
Speaker 2: cat scratch disease. I know, nineteen eighty.
Speaker 1: Three, eighty three, My goodness, so.
Speaker 2: Recent Yeah, and even then in nineteen eighty three the
Speaker 2: researcher was just able to say that this was a
Speaker 2: small gram negative bacillis. It took five years for the
Speaker 2: bacterium to be successfully isolated and cultured, and then it
Speaker 2: was named first Roschalimia Hensley and then changed to Bartonella
Speaker 2: Hensley Hensley after Diane M. Hens who isolated many of
Speaker 2: the original strains. Okay, this species, like Bartnella quintana, has
Speaker 2: made headlines over the past few decades, as you mentioned,
Speaker 2: due to its emergence as a threat for people who
Speaker 2: are immunocompromised, and also, as I saw in one paper,
Speaker 2: as a possible occupational hazard for people who routinely work
Speaker 2: with cats like veterinarians.
Speaker 1: Uh huh, definitely.
Speaker 2: So Erin, let's wrap this very interesting and all over
Speaker 2: the place episode up by talking about where we stand
Speaker 2: with all of these Bartnella today.
Speaker 1: Oh, let's try. But here's the problem, aren It was
Speaker 1: very difficult to find any kind of numbers in terms
Speaker 1: of overall infections, which is what I usually try and find,
Speaker 1: like current status, et cetera.
Speaker 2: To be honest, I'm not surprised by that, I know,
Speaker 2: and the other thing is that a lot of the
Speaker 2: papers that I FO that did cite some.
Speaker 1: Numbers were like ten years old. So we'll just go
Speaker 1: with what we've got, which is I'm not gonna lie.
Speaker 1: It's not great. Okay, Yeah, we'll start back at the
Speaker 1: beginning with Bartnella bacilliformis from a two thousand and nine
Speaker 1: paper that cited data from the Peruvian National Institutes of
Speaker 1: Health that was congregated from two thousand and four to
Speaker 1: two thousand and six, So this is old data, y'all.
Speaker 1: But they cited over that two year period in the
Speaker 1: early two thousands, more than twenty six thousand cases of bartnellosis.
Speaker 2: Wow.
Speaker 1: Yeah, it's more than I thought. And because the mortality
Speaker 1: rate can be high, this paper was saying that it
Speaker 1: can be estimated that just in Peru, and remember this
Speaker 1: is in at least three different countries, hundreds of people
Speaker 1: are likely dying every year from this disease.
Speaker 2: And how effective is antibiotic treatment if you get it
Speaker 2: early enough.
Speaker 1: It's a good question. It seems like it is effective,
Speaker 1: especially because a lot of the mortality is from secondary infections,
Speaker 1: so if you're able to tamp down the primary infection.
Speaker 1: But again, I don't have numbers on that, Okay, some
Speaker 1: other stats just to kind of get an overall sense
Speaker 1: of this, people have reported that in some endemic areas
Speaker 1: in Peru, up to forty five percent of people that
Speaker 1: live in those areas under twenty one show exposure, so
Speaker 1: they show evidence of having been infected at some point.
Speaker 1: So that kind of not only says this is a
Speaker 1: prevalent disease, but also maybe there's more asymptomatic or mild
Speaker 1: infections than we thought. Okay, right, so that's Bartnella bacilliformis
Speaker 1: Bartnella quintana. So difficult to get numbers on. We know
Speaker 1: that it's a big problem for people experiencing homelessness, both
Speaker 1: trench fever as well as endocarditis. The best I could
Speaker 1: find is that in studies where they have tested people
Speaker 1: that have been found to be infected with lice, anywhere
Speaker 1: from eight to fifty percent of people where SARAH positive
Speaker 1: for Bartnella quintana. So that doesn't tell us that much
Speaker 1: as far as actual numbers go, but I think it
Speaker 1: does tell us that this is probably far more prevalent
Speaker 1: than we think.
Speaker 2: Yeah, I mean absolutely, And like trench fever, I think
Speaker 2: people think oh, it must be a disease of the past,
Speaker 2: but is exactly not the case.
Speaker 1: And like I said, in terms of bacilliary angiomatosis, that
Speaker 1: is very low prevalence, like one in a thousand of
Speaker 1: people living with HIV, though it can happen in other
Speaker 1: people as well. And then we get all the way
Speaker 1: back around to BARTNELLA Hensley. What's the prevalence of this?
Speaker 2: Who knows?
Speaker 1: The CDC estimates about twenty two thousand cases every year,
Speaker 1: with about two thousand requiring hospitalization.
Speaker 2: Wow, okay, that's more than A thought to be more than.
Speaker 1: I thought as well. So we know that in a
Speaker 1: lot of places where they've tested cats, Sarah, prevalence and
Speaker 1: cats can be quite high. But even in some places
Speaker 1: where they've tested people, they have found that anywhere from
Speaker 1: five to thirty percent of people are sero positive for
Speaker 1: Bartonella Hensley. Lots of people around cats. Also, only about
Speaker 1: twenty five percent of infections are actually strictly associated with cats.
Speaker 1: So what like a known source like here's my cat bite,
Speaker 1: here's my infection, Aaron.
Speaker 2: Yeah, Hensley is by far the most.
Speaker 1: It's a different car, yeah, yeah, yeah. And then the
Speaker 1: really tough thing is quite honestly, there are so many
Speaker 1: more species of Bartnella, and there are so many case
Speaker 1: reports out there of cats scratch disease caused by this
Speaker 1: new specia, or trench fever caused by this other species,
Speaker 1: et cetera, et cetera. There are species of Bartnella associated
Speaker 1: with so many different mammals. Many of these can potentially
Speaker 1: cause zoonotic disease. They can spill over into humans, whether
Speaker 1: from whatever vector potentially right, and so I think in
Speaker 1: terms of like where is the research going, one of
Speaker 1: the biggest things we have to get a handle on
Speaker 1: is really just the breadth and depth of this genus
Speaker 1: of bacteria worldwide, What is its true distribution, What the
Speaker 1: heck are the details of how it causes disease. We
Speaker 1: really don't know a lot for people who are interested.
Speaker 1: We do have more detail on how it causes neoantiogenesis,
Speaker 1: like the formation of new blood vessels and things, so
Speaker 1: we'll cite those papers, but we still don't know a
Speaker 1: ton vaccines, we don't have any. I will link on
Speaker 1: our website to a paper that was interesting that found
Speaker 1: potential targets, because there's at least a theoretical possibility that
Speaker 1: people do mount a protective immune response to infection if
Speaker 1: they don't just become chronically infected. Okay, but you know
Speaker 1: it just it comes down to both, do we have
Speaker 1: the baseline knowledge that would be necessary first of all,
Speaker 1: and is there any funding for it? And I don't know. Yeah,
Speaker 1: So that's a bunch of different diseases, are different bacteria.
Speaker 2: Probably more than anyone bargained for.
Speaker 1: Definitely, I mean we did try and warn them three episodes.
Speaker 2: Yeah, Max eisodes. I like that. Yeah, should we do sources?
Speaker 1: We should definitely.
Speaker 2: Okay, I have a ton, but I'm going to shout
Speaker 2: out for that I found really helpful. One by and
Speaker 2: ste from twenty sixteen, The Centenary of the discovery of
Speaker 2: Trench Fever and Emerging Infectious Disease. One by Carrillas from
Speaker 2: nineteen seventy cat scratch disease notes on its history. One
Speaker 2: by Eiler from nineteen ninety six, Bartnella bacilliformis dangerous pathogens
Speaker 2: slowly emerging from deep background. And finally one from twenty
Speaker 2: twenty one by McKey. At all bat's our key host
Speaker 2: in the radiation of mammal associated Bartonella bacteria excellent.
Speaker 1: I had a lot of papers for this one. I
Speaker 1: think my favorite of just an overview of all of
Speaker 1: the different species of Bartnella was just called Bartonellosis. It
Speaker 1: was by Manguina at All and I'll post that. And
Speaker 1: then there were a couple of others like Bartonella species
Speaker 1: throwing light on uncommon human infections. There was one that
Speaker 1: was all of the different Bartnella species called Historical Pathogens
Speaker 1: of Emerging Significance. There's a bunch of good papers and
Speaker 1: we'll post every single paper on our website. This podcast
Speaker 1: will kill You dot com under the episodes tab we
Speaker 1: sure will.
Speaker 2: Thank you to Bloodmobile for providing the music for this
Speaker 2: episode and all of our episodes.
Speaker 1: Thank you to the Exactly Right Network, of whom we
Speaker 1: are very proud to be a part.
Speaker 2: And thank you to you listeners. We really appreciate you listening.
Speaker 2: Let us know how you liked this one.
Speaker 1: Yeah, was it fun for you? It was fun for.
Speaker 2: Us, It was fun actually.
Speaker 1: And thank you also to our patrons. We love you
Speaker 1: all so much, so much.
Speaker 2: Yes we do. Well.
Speaker 1: Okay, until next time, wash your hands, you filthy animals.
Speaker 1: M