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In episode 37 of the OFID podcast, OFID Editor in Chief Paul Sax, MD, and Jeanne Marrazzo, MD, professor of medicine and director of the Division of Infectious Diseases at the University of Alabama at Birmingham, square off in a spirited draft of the top animal-related infections.
Hello, this is Paul Sax [MD], I’m editor in chief of Open Form Infectious Diseases (OFID) and this is the OFID podcast. And as a reminder, that’s O-F-I-D and not “Oh-fid.”
Today I’m delighted, thrilled to host a long-time friend and ID colleague, Dr. Jeanne Marrazzo. She’s the C Glenn Cobbs professor of medicine at the University of Alabama, where she is also director of the Division of Infectious Diseases. She’s also a passionate animal lover, which should prove highly relevant to today’s discussion. Jeanne, welcome.
Paul, it’s so good to be here. And as I’ve told you, it’s so incredibly exciting to be able to have entire devoted time to talk about things that I love instead of COVID-19.
Excellent point. We could all use a break. So as she alluded to, today we’re going to draft our top animal-related infections. Importantly, I did not specifically define what I meant by “top” when I talked to Jeanne. It can qualify by being very serious, or having a cool life cycle, or just an amazing name or having a great clinical anecdote, or some combination of all of the above. And you can change the criteria between each selection. Now to get full credit though, we each have to say what animal is most strongly associated with this infection, and also why we chose it. And also importantly, SARS-CoV-2 is excluded, both because of the controversy over its origins and the fact that it’s just too depressing. So, ready to go?
I’m ready to go.
All right, Jeanne. As is customary for important people who appear on these drafts, who take time out of their busy schedule to do this, you can pick first. Go right ahead.
Well, let me tell you my criteria starting off. I picked things that are the sort of cases that if you were a medical student, you would get so excited about these infections that you would think, “Wow, infectious diseases is the coolest thing I’ve ever heard of.” And you get to see young people, you get to see older people and you get to see healthy people. And very importantly, for some of the infections I’m going to talk about, you can treat them. Which is another reason I’m glad we’re not talking about some of the other things that we’re talking about.
Okay. Excellent.
I will start with one of my all-time favorites, and I have a couple of clinical anecdotes with this, and a couple of them are recent. And that is Pasteurella multocida.
Oh, excellent pick. Not surprisingly, it’s on my list too.
Excellent. Not only does it have about the ultimate provenance of a name, Louis Pasteur, which is of course you should respect it just on that basis. But it’s kind of a cosmopolitan oral cavity bacteria, right? We think about it mostly with dogs and cats. And the reason I like it, first of all, it’s a little bit of an imposter. On Gram stain it can be very difficult to definitively identify. It’s often confused with the Gram-negative diplococci. And so people often think about a whole other cast of characters. And I guess we mostly think about it sort of being injected, into joints in particular. And I like that because you think of those little nasty, sharp cat bites. I think by the end of the podcast, it will be clear whether I’m a cat or a dog person.
Well, I’m a cat and a dog person. I’m mostly a dog person, but I’m married to a person who loves cats, has always had cats. So I think that’s a great choice, and it was going to be one of my choices too. And I’m just going to tell you that one of my clinical mentors, Dr. Arnie Weinberg used to teach about zoonoses. And he used to say that all cats, up and down the entire feline line, have Pasteurella multocida in the front of their mouths in those sharp teeth. So that means that if you get mauled by a lion or a tiger, you actually can die of Pasteurella multocida as well as die of hemorrhage. So I never went to the primary literature to confirm that, but it was definitely one thing I heard him say multiple times.
That’s the stuff of nightmares, actually.
Absolutely. And then as far as clinical anecdotes go, even though it’s most strongly associated with cats, I do distinctly remember a man who every day would read The Boston Globe with his shoes and socks off. And his German shepherd would lick between his toes. And he of course developed a prosthetic joint infection of his knee due to Pasteurella multocida. So that’s a great choice. I think it’s fabulous. I’ll cross it off my list.
My first choice is actually something that I’ve never seen, and hope never to see, and that’s rabies.
That was on my list too. Go ahead.
And when you contemplate serious animal-related infections, this one’s got to be the champ. It’s most strongly associated with dogs, of course, but here in the United States it’s a bat-related problem. And fortunately we only have a few cases a year, sometimes zero. And when they do happen, they’re almost always bat-related, and it leads to this challenging quandary of how we manage bats flying around inside a person’s house.
It’s interesting. We give rabies vaccine and immune globulin to people who wake up and see a bat flying around. Whereas the Canadians, they’ve decided that’s just too ridiculous because they estimated that the number needed to treat to prevent a case of rabies was something like one in 500,000 to a million. So they’re not doing it anymore. And they haven’t had a rabies epidemic because of it.
The last thing I’m going to say about rabies, and one reason why I really think it’s so cool is that it’s just one word. It’s kind of like Madonna or Prince, it’s that important. Rabies. That’s my number one pick.
My next pick is going to challenge you on that. But let me say something about rabies, speaking of anecdotes. So I saw a case when I was in Seattle, and it was a little girl who woke up in her bedroom and there was a dead bat. And the family didn’t really think anything of it. And at that point it was very early on in our recognition. This was probably about 20, maybe about 15 years ago. I mean, we knew that bats were a reservoir, but I don’t know that we had actually seen deaths. Or if not, this was among the first. Anyway, she died, delayed recognition.
Once you’ve seen that, it’s a little hard to ignore the bat thing. So we do it, also because people have no risk tolerance, right, for anything like this.
And then I guess the last thing is, so you haven’t used the medication regimen that was published in The New England Journal [of Medicine] several years ago, where they actually have the video of a young woman getting better after being treated. Which is worth pointing out for readers, just because it’s probably the only time you’ll ever get to see a video of somebody who survived rabies after being treated.
Sure, I completely agree with all those statements. I do think it says more about the United States personality versus the Canadian personality, that they don’t give the prophylaxis and we do. But nonetheless it is a real risk. What’s your second choice?
My second choice is also a single word. Plague.
Plague. Oh, that is a great single word.
It’s obviously Francisella tularensis, which has a fantastic name, right? I mean, something you should name your first born or something. So part of the reason I love plague is because it has many different forms. Classically the bubonic plague, but you can see pneumonic plague, which is of course a potential agent of bio terrorism. So it’s got this wide spectrum, but the animal cycles are so interesting.
I know you’re an avid reader, and I just finished a book called “Hamnet,” which if you haven’t read is a fictionalized take on Shakespeare’s son, who is thought to have died of plague. And the whole book describes the situation with plague at the time of this occurring.
And there is the best passage about the flea that ultimately came from the Middle East all the way to this little village in England to infect the kid. And if you are at all interested in life cycles, epidemiology, animals, I mean, it basically came from a street monkey someplace in Asia, got onto the boat, of course, millions of rats. And then the cats started dying. I mean, it’s like a horror movie. And so you got to respect that infection. It’s too cool. And we have it obviously, especially in the Southwest.
Yeah. We do have plague here. It’s treatable with antibiotics, which shows some progress.
So far both of mine have been, which I like.
Yeah, very good choice. I will say that it wasn’t on my list, but as I mentioned, Pasteurella multocida was so my original number two is now being replaced by my number three, which is toxoplasmosis. I do think that this is the single best name of all of the animal-related infections, Toxoplasmosis gondii. In fact, my son was very precocious with his verbal skills and it’s one of the first things I taught him to say, because he could say anything. And I said, “Joseph, say toxoplasmosis.” And he could say “toxoplasmosis.”
Maybe a child protective services call.
Yes, exactly. But anyway, it sounds like something from science fiction and it’s obviously a cat-related infection – they’re the definitive hosts. But little-known fact that we, of course ID doctors know, but not everyone knows is that most people who get toxoplasmosis get it from dietary habits – not from changing the kitty litter, but from eating undercooked lamb, pork and beef, and another little-known fact, shellfish. So even though it’s associated with cats most strongly, you get it from eating those foods.
A couple of other reasons I chose it is that it’s an HIV [human immunodeficiency virus] disease among the opportunistic infections. It’s the one that looks so terrible on scans when it causes cerebral infection, but it’s actually very responsive to therapy. And even before we had effective ART [antiretroviral therapy] people responded beautifully. And then the last thing I want to mention, I’m just sort of curious. In your opinion, there’s this weird literature about toxoplasmosis and psychiatric disease. Do you think that’s true or is that just nuttiness?
I think it’s probably association by true, true and unrelated. That said there could be subtle changes in brain function that we just don’t mean. When we think about toxins in the brain, there are insistent organisms. And so maybe there are some subtle things going on in people who have completely asymptomatic [infection]. I don’t know. You can never say never with this stuff, especially with brain stuff. I just don’t know.
Good point.
Let me ask you a quick question about this. Do you still get toxo serologies in your newly diagnosed HIV- infected patients?
The answer is yes, because old habits are hard to break.
That’s what I thought. That’s a lot how I feel. I feel like I probably don’t need to do that anymore. Although here we see people diagnosed so late here in Alabama, that...
Yeah, for a person newly diagnosed with low CD4 cell count, absolutely. But if you were thinking about it and you saw someone who didn’t have a low CD4 cell count and put them on ART, it would not be necessary. But it’s not expensive and yes, we do get it. All right. What’s your third choice, Dr. Marrazzo?
All right. Well, it’s getting a little hard, because I love them all so much. But I am going to have to say that I love Francisella tularensis. I’m in the Francisella mode right now so I’m on a streak. Tularemia I think is really, really interesting for a couple of reasons. And then I want to tell you an anecdote that I really love. I think it’s interesting because of course it’s associated with very specific exposures. You pretty much need to be outdoors of course, but the way you get it from outdoors is very interesting. The classic outbreak occurred in Martha’s Vineyard, with the people who were mowing the lawn, who basically were pulverizing and chopping up baby rabbits without knowing it, inhaled the particles from the baby rabbit as they were churning under their lawn mower. And they all got tularemia pneumonia.
So it can cause a really bad pneumonia. In fact, the best case of tularemia I ever saw, which was my other epidemiologic anecdote, is that in Fairbanks, Alaska, they actually have a summer pneumonia season and it’s caused by tularemia. It’s a classic infection. I saw a young man from Fairbanks, who was admitted to our ICU [Intensive Care Unit] in Seattle who had a very, very significant atypical pneumonia. It’s related to cycles in the snowshoe hare population. So the dogs eat the snowshoe hares, usually the sled dogs. See, this is why, if you do this stuff, how can you not do ID? The dogs eat the snowshoe hares. They bring it home, they get infected and then people can get infected from that. And then it causes, of course the famous nodular lymphangitis as well, which I love. And a few other things, Parinaud oculoglandular disease.
Yeah, very good choice. And also, it speaks to the beauty of the language of our field, both Francisella tularensis, and then the name of the disease, tularemia. What a beautiful word.
It’s a really cool word. And it’s really all about lagomorphs. So rodents are really the big issue here.
Good choice.
And treatable.
My next choice is a really common one, but an important one. And I’m going with malaria. And malaria, which has obviously multiple different plasmodium species. And I chose it because of that quiz question you can give to people and say, “What’s the most deadly animal in the world?” And you can show them pictures of the grizzly bear and the great white shark, etcetera. But most people would estimate, aside from us humans, of course, that it’s the mosquito, and that this tiny little thing can kill so many people. And the vast number of these deaths are malaria deaths, and they’re malaria deaths in really little children, so huge years of life lost.
Also for those of us who practice in places like Boston, Massachusetts, every case of malaria is exciting. I hate to say that because it almost implies that we’re taking pleasure in someone’s illness, but it’s exciting because you can make the diagnosis and you can treat it. And most of the time the outcome is excellent.
And there are days even in Boston where I recall that this was actually an endemic infection in the United States until very recently, because it gets so hot and humid here. But I don’t need to say that to someone from Alabama, because you probably have malaria-like weather the whole summer long.
Yeah. Well, luckily we don’t have malaria. Thank goodness.
So that was my next choice. Going down to number four now.
Well, I’m going to have to do echinococcus.
Oh, great one.
I’ll say Echinococcus multilocularis, although you could do granulosis. Again, because of this relationship to anecdotally having seen one, and so a little-known reservoir of Echinococcus multilocularis, if you haven’t lived in the Pacific Northwest, are rodents endemic to the Arctic circle. So in the Yukon, so lemmings and all these other things. Again, sled dogs are out there, dogs are out there, they’re eating wild rodents, they can get infected, and then they can infect their human hosts.
And the other thing about multilocularis is, and this is not a very common disease as far as we know, it can actually be confused with a hepatocellular carcinoma because you get very rapid increase in your hepatic mass and can get biliary obstruction pretty quickly. So I think it’s got a really cool life cycle. And again, it’s just one of those things that once you see a case, you are not going to forget it.
Yeah. It’s really challenging to treat. I’m not a parasitology specialist by any stretch of the imagination, but have come across a couple of these cases and wow. Talk about time to phone a friend. I fortunately work with Dr. Jamie Maguire who’s a real expert in parasitology, but I’m sure that most ID doctors don’t feel like they have the expertise to manage cases of echinococcus.
Especially if you’re talking about surgical removal, what you do with cysts. And you also need a surgeon, somebody who’s actually done it before, so that you avoid the intra-abdominal catastrophe of cyst rupture.
Yes, absolutely. Good choice. Wasn’t on my list.
It’s a good dog one.
Oh yeah, very good dog one. Remember, you and I love dogs anyway. Right?
Yes.
It doesn’t matter that they have all these diseases.
Seriously. I was reviewing the list of dog-associated diseases, just to remind myself, and I’m thinking, “How can I even have a dog? This is terrible.”
Wait, you have two dogs. Don’t you?
I have two dogs, yeah.
Okay. My next one is a little bit off the board. I’m going a little bit far afield because I just want to say it. Okay? My next choice is Erysipelothrix rhusiopathiae.
Oh, I love that. I was going to say that too, because how often do you get to say that?
Not very often. And the thing is, by living here in New England, anything so strongly associated with fish and lobsters just has to be chosen. I will now say most commonly, we don’t diagnose this because Fish Handler’s Disease, which is caused by either this bug and it causes a cellulitis-like issue, or it’s caused by M. [Mycobacterium] marinum, with the cellulitis-like issue, you hardly ever culture it. But every so often you will see an invasive case, and then it grows in blood cultures.
And the most memorable one I’ve ever seen was with somebody who had kept a fish in his downstairs freezer and he let it defrost. And then when he was handling that fish, the spine broke through his skin. And he shortly after developed cellulitis, bacteremia, and endocarditis. And it was a tremendously exciting little piece of history to piece that all together. Not obtained by me, of course, but by the astute ID fellow. And it was a really remarkable case. So I’m going with Erysipelothrix rhusiopathiae. I think it’s not common. And the fact that I can just say it, I’m just proud of that. So that’s why I chose it.
You should be extremely proud of it. That is amazing. I’m going to have to reserve a few if we get short on time that I can list just because I like to say their names.
Okay. No, absolutely. One of the great things about these podcasts is that we have an unlimited amount of time to nerd out as much as we like on ID facts.
That’s a little scary, actually.
But I did ask you to choose your top five, and you’ve come now to your fifth one. So go ahead.
Fifth one, my top five? I thought I had 10.
Nope, top five. You can give the honorable mentions in rapid fire.
Oh, crap. Okay. Well, I’m going to have to go with, it’s kind of a humdrum thing, but I have a new respect for it since I’ve moved to Alabama. I hope people aren’t offended who love this organism, Cryptococcus neoformans. First of all, I feel like I have grown up with Cryptococcus as it’s evolved. My first patient that I ever saw with Cryptococcus was a patient who had a history of lymphoma, who then several years later presented with cryptococcal meningitis, not HIV, it was when I was very early on. And then of course so much of it being seen with HIV, but here in Alabama because we have so much endemic mycosis because of the climate, really it’s sub-tropical here, we see a ton of crypto and about 25 percent of people are “normal hosts.” And I have just grown to respect the spectrum of clinical presentations with this organism in a way that I had not appreciated before. So how is it linked to animals? Birds.
Yeah it’s probably a bird reservoir – I agree with you. Clinical presentation is so wide. And sometimes it’s very indolent, very hard to diagnose the hosts who I think most of the cases we see now are people who have liver disease. It seems to be very common and it’s really hard to manage. So that’s a very, very good choice. It’s not one I think that most people think of as a zoonosis, but you made the point that the birds are the likely source.
Exactly.
Okay. So my last choice in my top five, I decided to go with schistosomiasis, and I went for schistosomiasis because I wanted to have at least one of those crazy CDC [U.S. Centers for Disease Control and Prevention] life cycles. And I’ve always thought that the life cycle of schistosomiasis is so bizarre and who figured this one out? And obviously the animal it’s linked to is snails, right? So you’ve got these snails swimming around fresh water, and then they release these free living things called cercariae that penetrate into the bather’s skin, which is why you never want to swim in freshwater lakes in Africa. And then they go in, change their form in your body, and then they release the male and the female who then get into your portal veins and reproduce right there in your portal veins and release all these eggs, which is really staggering. And those eggs then get released obviously in the GI [gastrointestinal] tract or in the urine, or both. So I’m going with schistosomiasis based solely on the truly bizarre life cycle and the amazing respect I have for the people who discovered it.
I could not agree more. A little-known fact, you can get avian schistosomiasis from swimming in Lake Washington in Seattle. It’s very common any place where there’s not good-moving water in temperate regions. So it’s around in the United States. So the old timers who used to swim in the lake always used to immediately take a shower after you get out. So that’s how you can prevent it, because basically you just don’t give the organism time to penetrate into your skin.
Yeah. I think avian schisto doesn’t cause the severe disease that the other schistos do, but it still is very annoying. Right?
And a great differential for common rash in summer, especially in kids.
Yeah, absolutely. All right. So now you get to do rapid fire, your honorable mentions. Why don’t you choose three?
Okay. I can’t wait to say this one. I know you will know what it causes, but it’s just too cool. Mycoplasma phocacerebrale.
And enlighten me. I have no idea what that is.
Well, good. It’s a mycoplasma, it’s P-H-O-C-A-C-E-R-E-B-R-A-L-E. It causes something called seal finger, which I have seen. And so it is a mycoplasma and only described pretty recently because people knew that you get this very specific infection if you are bitten by a seal or handle a seal. Again, it got to my Arctic interests. I know this is not that rapid-fire, but bottom line, it usually didn’t respond to any of the typical antibiotics used for cellulitis, probably because it was a mycoplasma. It doesn’t have a cell wall so you have to use a tetracycline. So anyway, I love that. I just love the name. I love the story.
That’s good.
And if you see a person who has a seal bite, that’s what you got.
Actually, now I do remember one of my co-attendings did a consultation for the New England Aquarium.
Exactly. Yes. That’s why it’s good to know about it. Because you don’t have to be salmon fishing in the middle of the Bering Sea to experience it.
Alright. So that’s a good one. You get two more rapid fire ones.
Okay. I really love Rhodococcus equi, largely because of its name and because it’s from horses, and I have seen it. Have you seen a case?
Yes, I have. In fact, I’ve seen a cavitary disease in a person with HIV that was mistaken for tuberculosis and it wasn’t. Not so easy to treat those Rhodococcus cases.
No, they’re not. And they’re really interesting and it’s not that easy to make the diagnosis. And I think it’s a fascinating infection. Horses don’t seem to get very sick from it, which I thought was interesting. In contrast to my next one, in which the host does tend to get sick, which is Chlamydia psittaci.
Ah yes, definitely.
Psittacosis is a great diagnosis to make. And the only clinical pearl I have about that is the bird is often sick. They have something called the ruffles. So their feathers are kind of ruffly, they can have diarrhea. And then I think complaints of headache with psittacosis are probably some of the worst I’ve ever seen. If you have a young person who has an unbelievable headache with a pneumonia, it could be lots of things, but always ask them if they have a bird.
That’s excellent. And you are married to a bird lover, as I recall.
Yes I am. I am one too.
Okay. The others in my rapid-fire completion, I’m going to use just a couple and I’m going to go with two more dog-related infections. I can’t resist saying Capnocytophaga canimorsus.
I knew it was coming.
Especially since I think when you and I were ID fellows, it was called DF-2.
And you know what that stood for? My favorite thing.
Dysgonic fermenter.
I wish we had made a band that was called Dysgonic Fermenter.
And ask people what dysgonic means and nobody knows.
Exactly. I have no idea. I know. DF-2. I love that.
The latest hit from DF-2. Okay.
So Capnocytophaga canimorsus, clearly a major, serious infection in splenectomized hosts and people with alcoholism. But then also I have to just say that you can’t finish anything about dogs without mentioning puppies. And I’ll just mention Campylobacter jejuni, because the source of some of the largest Campylobacter outbreaks have been puppy mills. And so I did want to mention that one. So those are my last two in my series of honorable mentions.
This has been a joy from start to finish. We have been drafting our top animal- related infections for this OFID podcast. And I’ve been talking with Dr. Jeanne Marrazzo, Professor of Medicine at the University of Alabama. Thanks, Jeanne.
Thank you, Paul. I really enjoyed it and stay safe.
Bye.