Botulism: Medicine, Menace, and a Masterclass in Food Safety

Imagine a toxin so potent that a few nanograms can shut down a muscle—and yet, in the right hands, it eases migraines and calms spasms. We take you from the sausage-linked origins of botulism to the science of spores, food safety, infant risks, wound contamination, and the carefully controlled medical use of botulinum toxin. Along the way, we unpack how this anaerobic bacterium survives heat, why improperly canned foods can become dangerous, and what really happens at the neuromuscular junction when acetylcholine release is blocked.

We break down the top-down pattern of paralysis—double vision, drooping eyelids, trouble swallowing—and why sensation stays intact even as movement fades. You’ll hear practical prevention tips for home canning and fermentation, the reason honey is off-limits for infants, and what to do if you suspect exposure. We also explore diagnosis and treatment: toxin detection, antitoxin for adults, immune globulin for infants, and the crucial role of timely supportive care when breathing muscles weaken.

Then we shift to the paradox of Botox. Type A botulinum toxin is FDA-approved and widely used for migraines, dystonias, overactive bladder, and cosmetic goals, yet outcomes depend on expertise, dosing, and aftercare. We discuss diffusion risks, emerging research on toxin migration in animal models, and how to choose trained, licensed providers. Rounding out the story, we touch on botulism’s biosecurity history and why strong surveillance and sound public health systems matter just as much as good kitchen habits.

If this exploration helped you see botulism with fresh eyes, subscribe for more science you can use, share the episode with a friend who loves microbiology and medicine, and leave a quick review to help others find the show.

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Transcript

Framing One Health

SPEAKER_02 0:00

This is the podcast about one health. The idea that the health of humans, animals, plants, and the environment that we all share are intrinsically linked. Coming to you from a team of scientists, physicians, and veterinarians, this is infectious science. Where enthusiasm for science is contagious. Alright. Hello everyone. Welcome back to this episode of Infectious Science. We're going to talk about one of the most poisonous substances on Earth. It's been linked to everything from food poisoning to doomsday cults and cosmetic treatments. So pretty broad. So we're going to dive into the science behind a neurotoxin-producing bacteria known as Clostridium botulinum. This has caused unintentional food poisonings, has been used by humans intentionally as a bioweapon and also as a cosmetic treatment. And Clostridium botulinum causes the rare poisoning known as botulism. So to start off, I just want to start us off with some history. So let's get into that. The discovery of botulism is actually credited to a German physician. So that should make you very happy, Dr. Benza. So this German physician named Justinius Kerner, which I'm probably mispronouncing. I don't know if there's a German way to pronounce that. Is there? Kerner?

SPEAKER_00 1:14

That's close enough.

SPEAKER_02 1:15

Close enough. Okay. It's possible. This was back in 1793 and found botulism in spoiled sausages. So botulus, which is the root of the word botulism, is Latin for sausage. So I think that's just a fun anecdote.

SPEAKER_03 1:30

Wait, that's so funny. I didn't know that.

The Bacterium, Spores, and Conditions

SPEAKER_02 1:33

Yeah. But um, it's it comes from sausage. So I don't know. I think that it's a cool little I love to, I've been looking into the root roots of like words recently. So that's fine. And then a uh uh so then after it was discovered by a German physician, so he found botulism. But Emile Kahn Urban Gem is the one who identified the Clostridium botulinum toxic bacteria as the source of a Belgian botulism outbreak. And so then botulism outbreaks in 1919 and 1973 in the US are what led to basically federal regulation of food preservation that demanded high temperatures and then safe processing to protect consumers from the deadly toxins. So most people think of botulism these days as a foodborne illness, basically. So I just want to get into how exactly it causes illness. And I know, Christina, you probably have some to contribute here, but I'm gonna give an overview of the organism. And then if you want to jump in on more like symptoms and how we see this in people, so it's spore-forming bacteria. The spores are really commonly found in soil. They are super resistant to heat. They have a potential to survive a hundred degrees Celsius heat for several hours, which is very resistant. Oh my gosh. Most bacteria are long dead by then, I would say. It's also really resistant to light, desiccation, and radiation, which is interesting. So they can really, these spores can survive a great deal of time, particularly in the right conditions. And they wait until those right conditions that kind of, I don't know, humanizes them. They're not waiting, but when the conditions are right, they will terminate. And those conditions have to be warm, mildly alkaline, and anaerobic, which means it's lacking oxygen. So you can probably think that a great environment for them would then be in something like a can of preserved food where the oxygen has been removed, and also it's probably sitting at room temperature in your house. So this is the ideal conditions for them. So we'll talk about later, like how we now know that canned goods are safe or not from botulism. And what's also interesting is that people that can their own goods, a lot of that is based on making sure you are safe from botulism. Exposing the spores to moist 120 degrees Celsius heat for 30 minutes is effective at killing them. But as it's cooking food at 80 degrees Celsius for 30 minutes, which will destroy the toxin, but it won't destroy the spores. So ADC for 30 minutes, toxin is destroyed, the spores are still potentially there and could still potentially germinate. And once they germinate, that's when the neurotoxins that cause flaccid paralysis are released.

SPEAKER_03 4:09

Yeah, and just like a little bit of information on how that happens, the flaccid paralysis. So the toxin itself basically prevents the release of the signals in our body that allow us to move, right? And so by preventing the release, you can't move anymore. And so that's how it causes that flaccid paralysis in us. But the actual spores themselves don't really do anything, it's the toxin that they then release.

Toxin Action and Human Types

SPEAKER_02 4:32

Yes, absolutely. And it only takes a few nanograms to cause severe illness, which is really unique. That is a very small amount. Nanograms are minuscule amounts. So one human cell weighs about one nanogram. Or if you put that another way, if you like sliced a single grain of rice into 25 million parts, one of the 20 parts would weigh one nanogram. So it only takes a it's crazy. A body to make you incredibly sick or even to kill you. So that tells you how little it takes. I just thought when I was coming across those comparisons, I was like, wow, that is such a minuscule amount. So it's like there can be truly almost none of this in anything you eat, or you're risking plastic paralysis. And so these are incredibly small amounts, but they're very deadly. So just as you said, the deadly toxins, they cause paralysis by binding in near muscular junctions and they prevent the release of acetylcholine, which is a neurotransmitter that is incredibly crucial for muscle movement. If you want to be moving, you need acetylcholine. And there's different types of toxins too, but only A, B, and E are known to affect humans. So those are basically it usually is occurring because of ingestion, either because you ingested the bacterium itself, the neurotoxins, or the spores. So it might have already, spores might have already germinated uh germinated, and there's toxin in whatever you're eating or ingesting. The bacteria is in there, and then you're gonna have the kind of eventual release, or you have ingested the spores, and then they can actually germinate within you and release the toxin. So all kinds of not fun ways that it can affect us.

SPEAKER_03 6:04

Yes. That does not sound good.

SPEAKER_02 6:07

No, not at all. And I didn't realize that once they're ingested, the bacteria can incubate in the stomach and they can produce spores which release toxins. I can't think of anything else off the top of my head that can just handle the acidity and the how like severely our stomach is just is meant to get rid of things and not let something like this happen. So it's pretty unique that this can survive that and then germinate and release toxins. I think that's pretty wild. Yeah. But, anyways, the most rapid progression of disease is caused by ingesting food that's contaminated with the neurotoxin itself. So that would mean that a clercigen botuline was in it, the or the spores were, they germinated and the toxin was already produced. So if the toxin is in whatever's being ingested, that's the kind of the fastest way that we see paralysis happening. But there's other ways to get botulism. You can also get it from spore contamination of open wounds, which I didn't know until I was researching this episode. But what I think is really interesting is despite there being outbreaks of botulism, there's no secondary person-to-person transmission of botulism that has ever been documented. So someone around you could have botulism, and you're not going to get sick, but unless you were eating the same food or something. But like you can't get it from them, essentially, is what that means. And the incubation period really ranges for this once either the bacteria, the spores, or the toxin has been ingested. It can range from hours up to two weeks, depending on whether it was the bacterium, the spore, or the toxin that was introduced to the body. But yeah, I don't know, Christina, do you want to get into the symptoms of botulism besides flacid paralysis? I can also jump into them too.

SPEAKER_03 7:42

Yeah. So at least what we're taught in medical school is that botulism presents as like a head-to-toe, so top-down paralysis. So the first symptoms that we're taught about is myopia, which is double vision and also drooling, right? And so you have this kind of double vision, hard to keep your eyes open, start to drool for that you can't explain. And it's because all those tiny little muscles in your face to keep your eyes open, to keep your eyes centered and moving together and coordinated, and then the muscles in our throat and our mouth, everything like that, kind of provide that stabilization, I suppose, are the first to become affected, right? Because of the ones that we use so frequently as well. And so because those kind of go, we start to notice the symptoms that we normally take for granted. So the double vision, the drooling, and then it works its way down. But the thing that's really dangerous about botulism, as I'm sure a lot of us can imagine and understand, and the way that most people end up dying from this is once it gets to the muscles of your diaphragm. And so the diaphragm is a muscle, even though we don't really think about it as one, because we don't actively think about our lungs being opened and expanded and closed. But the diaphragm really does a lot of that heavy work. And if that muscle itself gets paralyzed, we can't breathe anymore. And so unfortunately, that is typically the most dangerous presentation of botulism and the one that presents as the most lethal symptom of infection.

Symptoms and Respiratory Risk

SPEAKER_02 9:09

Yeah, no, absolutely. Paralysis of respiratory muscles is absolutely what's gonna often lead to death in botulism. And besides the paralysis and what you talk about with like double vision, difficulty seeing and swallowing or speaking, there can also be like nausea, vomiting, diarrhea. In infants, it's usually lethargy and weakness, is how it's presenting. But I found something interesting that I actually was curious if you could clear up for me. I found evidence that suggests that the sensory nerves are not affected by botulism. So I would interpret that as you can feel things while paralyzed, but you can't move. Is that do you think a correct interpretation of that?

SPEAKER_03 9:43

Yeah, I definitely do. And it's because botulism itself isn't going to affect like the what's it called? The the sensations, because it inhibits acetylcholine, which for the most part plays the most active role in actual muscle movement and kinetic energy and stuff like that, but not so much in perpetuating or projecting sensory input and output through the body.

SPEAKER_02 10:04

Yeah, yeah. And that also just that sounds just like a my worst nightmare. I don't know.

SPEAKER_03 10:09

Sounds like a horror movie.

SPEAKER_02 10:11

I don't know if anyone listening has ever experienced sleep paralysis, but I used to experience sleep paralysis. And you're awake to some degree, you're awake, but you can't move because you are still paralyzed in your body's still interpreted as I'm paralyzed because I'm sleeping. And so it feels awful. Like it is the worst thing. And I feel like it seems to me like what botulism would feel like is that like you can feel things, like you can feel that there's the covers on you, or you can feel your pillow or whatever, but you can't even twitch your fingers. And so to me, that is the ultimate horror. I hate it.

SPEAKER_03 10:41

Yes. Oh my gosh. Yes.

SPEAKER_02 10:44

I think it's pretty common. Like it's just a little bit of a mismatch that your body is kind of awake, but not really awake. But yeah, I was like, oh, I'm awful.

SPEAKER_00 10:52

So yeah, I feel like a lot of those signs and symptoms sound so terrible. Tristina was saying like a horror movie, right? Like it's just crazy stuff. And one thing that that when I learned about botulism, I you hear these terrible stories of the terrible way we can die based on this, right? But I always wonder what's how often does this really occur. And I know it's fairly rare in the US, but it's consistent. I think that consistently like around 200 cases in the US, sometimes less, sometimes 150, sometimes 250, or something like that. Mostly around 200 cases per year. So it's a consistent case. And 70% of those cases are actually infant cases. 20% or 25%, maybe like wound contamination, like you said, Camille is for us. The rest, I think, is food poisoning. But can we talk a little bit more about the infants side of the clinical presentation?

Sensation Intact, Movement Lost

SPEAKER_02 11:46

Yeah, I have a little bit on this, and I know Christina and more about it, but I know that one unintentional botulism exposure is infant botulism, which really it occurs on average in two infants per 100,000 live births in the United States. And it occurs when botulism scores are digested. So usually that's from honey, corn syrup, food, or dust, from what I was reading. And this is why honey jars are labeled with do not feed to children less than one year old. But yeah, Christine, I don't know if you want to get more into that.

SPEAKER_03 12:13

Yeah, so when we're infants and when we're children, our immune systems are still developing. So they're not fully developed whatsoever. What we learned basically in school is that as infants are developing, they don't have as mature of a digestive tract or a digestive system as adults have. And as a result, the infant digestive system itself is a less acidic environment. And so infants themselves are more prone to having more serious GI infections. And if botulism, something that's so aggressive, is introduced to the digestive tract, it can result in much more devastating effects than it would be if it were introduced into the digestive tract of an adult. So that's just why we recommend not giving infants honey or anything like that. You know, honey is sticky, it's an anaerobic environment, it's like that niche environment for the spore to drive in. We really recommend not giving honey to children because historically it's been something that has shown to perpetuate this infection within infants and children. And so we have seen just a few cases of botulism infections and toxin exposure in infants who have been given honey.

How Common Is Botulism

Infant Botulism and Honey Risks

SPEAKER_02 13:24

Yeah. And I also want to talk a bit about what do we do when we suspect botulism. Usually a mouse neutralization test is used to detect. So if it's suspected, basically what's done is that serum or stool from a suspected case is injected into a mouse, and then that mouse is observed for signs of botulism. And once you confirm that it's botulism, there's an toxin that's available. But for infants, there's an immunoglobin. And that's a protein that's found in blood that contains antibodies, for those who don't know. And that's been approved for toxins A and G. So we can treat those, but as I mentioned earlier, there are other subtoxins like so A, B, and E all affect humans. Oh, and F also affects humans. But we only have something for toxins A and G, as far as I know, for that. But as you were mentioning, Dr. Mente, that there's a lot of other ways that people get botulism now. So usually the biggest risk factor for unintentional exposure is people canning their own goods like vegetables or fermented fish. You can easily be exposed to botulism there. 50% of US foodborne botch breaks are caused by type A toxins, which are usually found in canned goods. And then whereas like fermented fish products are usually associated with like type E toxins. And then wound botulism, I touched on earlier, but just to expand on it, it's when you have dirt or gravel that gets into a wound that is anaerobic, which means it's lacking oxygen. And it's often associated with use of what's known as like black tar heroin. And it's probably due to like contamination during like the drug prep process. But yeah, and so this is why also if you think about botulism, this is why if you've ever heard that you should discard food that's in dented cans, it's because of the risk of unintentional botulism poisoning. Basically, canning, if the stuff you're buying in the store, is safe because it removes the air from food and that it's heated and all that stuff. But if it's dented, that air has been removed. So it's an anaerobic environment. It's probably potentially more alkaline conditions and it's warm conditions. And so that creates a good environment for botulism to grow if it's dented or pierced and sheep botulinum is around. So that's a concern, is that cans themselves, there's high safety standards, but when they're dented or they're pierced, there's the potential for introducing it. Also, I did not know this until I started reading a bunch of botulism, that botulism has been used as a bioweapon, which I was not aware of at all. A large concern with it on the bioweapon front is that not only can food be contaminated, which can cause an outbreak, which we have seen food outbreaks, not intentional ones, but the neurotoxin can also be inhaled, and that makes it really dangerous. So in 1990, 1993, 1994, and 1995, a Japanese doomsday cult called Riki, it's now known as ELF, actually released botulism toxin aerosols in Tokyo. But very fortunately for everyone, these attempts failed. They did later attempt, I think it was sarin, and a lot of people got hurt or died. But if you want to learn about an instance of botulism being used as a voucher weapon with really deadly consequences, you should check out season one with the episode Poison and Poetry, where botulism was found to be the cause of death for a poet. And Dr. Mental Kurt, if I'm wrong, but I believe the government was trying to silence him, right?

SPEAKER_00 16:27

Yeah, that's correct. Yeah, we had Alfredo Torres on talking a little bit about the history of how the poet was killed for standing up to the government. So really interesting story. Go back to that episode for sure.

SPEAKER_02 16:39

Yeah, yeah. It's really wild. I do want to talk about one way that adults intentionally get exposed to botulinum toxin. Yes. Botox prevents muscles from moving for a limited time. So that can help prevent things like migraines. It treats overactive bladder, it also treats the neck spasms. It's also been used cosmetically to smooth facial wrinkles and really relax muscles that can cause frown lines. So Botox injections are made of FDA-approved purified botulinum toxin. While considered safe when use is directed by a licensed healthcare provider, it is worth mentioning that the toxin can spread to other parts of the body other than the injection site. That can lead to vision problems, trouble swallowing, difficulty breathing. If a patient lies down within two to four hours after getting the procedure, or if you rub the treated area after getting a Botox injection. And something that I found, which was really wild, is that a recent 2024 article from Science highlights that despite 25 years of use with few complications, Botox has recently been found to migrate from the skin to the central nerve system after injection in mice. So this is in mice. Doesn't necessarily mean that the exact same effect is happening in humans, but it's worth considering that you don't want bodulum toxin in your central nervous system. And you really don't want it anywhere in the body. But if you're getting Botox injections, you definitely don't want it outside of the area where it's being injected for whatever purpose, whether that's to prevent certain muscles from moving and prevent like spasms or for something cosmetic. So also just for reference, the toxin most commonly used in cosmetic Botox injections is type A toxin.

SPEAKER_03 18:14

Yeah. Yep. And I think that just points out why it's so important that if you are getting Botox injections to go to someone who is really well trained in this, uh licensed, has had years of practice giving this treatment because nothing comes without a risk, right? And the risk of some treatments is a lot higher than others. So when it comes to getting your Botox, just make sure you're doing your research and going to someone who has a lot of experience in what they're doing.

SPEAKER_02 18:40

Yeah, absolutely. And I think that's always a thing, right? When it comes to your health, that's not the place to ever cut corners.

SPEAKER_03 18:46

Yes, exactly.

unknown 18:48

Yeah.

SPEAKER_02 18:48

Cool. We went over a lot in this episode. So we hope that you enjoyed it. That's all I have on botulism. I don't know if either of you have some closing thoughts to add.

SPEAKER_03 18:57

I do remember one of the first episodes that I listened to of the podcast when deciding to join the podcast in the first place was that previous episode on botulism. So I really recommend whoever's listening to this episode to go back and listen to that one as well because it's a really fun episode.

SPEAKER_02 19:13

Yes. And that's season one, Poison and Poetry. All right, everyone.

Diagnosis and Treatments

SPEAKER_01 19:17

As always, thanks for listening. Thank you. Thanks for listening to the Infectious Science Podcast. Be sure to hit subscribe and visit infectious science.org to join the conversation, access the show notes, and to sign up for our newsletter and receive our free material.

SPEAKER_04 19:31

If you enjoyed this new episode of Infectious Science, please leave us a review on Apple Podcasts at Spotify. And go ahead and share this episode with some of your friends.

SPEAKER_01 19:40

Also, don't hesitate to ask questions entitled to what topics you'd like us to cover for future episodes. To get in touch, drop a line in the comments section or send us a message on social media.

SPEAKER_04 19:49

So we'll see you next time for a new episode. And in the meantime, stay happy, stay healthy, stay interested.

SPEAKER_02 19:56

This podcast is sponsored in part by the Institute for Collaboration and Health, an action-oriented nonprofit that partners with innovators in science and health, working with communities to develop nimble approaches to the world's most challenging health problems.