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The Dose Transcript for November 14, 2024

Host: Dr. Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. You may have heard a lot lately about a disease called walking pneumonia. It affects mostly kids and teens, and to a lesser extent, young adults. It's milder than the kind that lands people in hospital, but it can be serious. Cases of walking pneumonia have spiked across much of Canada. I myself have seen it and diagnosed it in the past few days. So this week we are asking: What do I need to know about walking pneumonia? Hi, Caroline. Welcome back to The Dose.

DR. CAROLINE QUACH: Hi, Brian. Thank you.

BRIAN GOLDMAN: I've seen a lot of stories about this in the news. What is it about walking pneumonia that's captured the attention of Canadians, do you think?

DR. CAROLINE QUACH: I think it's the fact that we're actually talking about it that probably a lot of parents have seen their children be diagnosed with it. And even public health is worrying because they seem to be seeing more cases than what we tend to see in a regular fall season.

BRIAN GOLDMAN: So we've established that people are talking about it, particularly parents. And that's why we've got you as a pediatric expert to talk about this important subject. But before we begin, can you give us a hi, my name is? Tell us what you do and where you do it.

DR. CAROLINE QUACH: Hi, I'm Dr. Caroline Quach. I'm a pediatric infectious diseases and medical microbiologist and professor in microbiology at CHU Sainte-Justine, a pediatric hospital in Montreal, Quebec.

BRIAN GOLDMAN: Now, newsflash for people listening to this conversation: walking pneumonia is not a clinical diagnosis, but it's out there as a term. So Caroline, how do we define walking pneumonia?

DR. CAROLINE QUACH: Well, it's basically a pneumonia that is a pneumonia, so you need an X-ray to know that your lungs are affected. But you're usually not as sick as what we tend to see with your regular pneumonia, or what we also call [indistinct] pneumonia. So you might have a little bit of fever, you have cough, you're not feeling that well. But you're still able to walk out of bed and go to school or do your regular activities most of the time. And that's why the term walking pneumonia.

BRIAN GOLDMAN: What are the typical signs and symptoms of walking pneumonia?

DR. CAROLINE QUACH: People feel tired, unwell. They might have a bit of fever. They will cough and the cough will not get better, you know, like your usual virus, which tends to go away with time. This one tends to linger on and on. And eventually, because you're not feeling better, your parents bring you to either the emergency room or your family physician, pediatrician, at which point in time you get an X-ray. And the X-ray, instead of seeing this big patchy pneumonia in one lobe of your lung, will have this nice little infiltrate that could even look a little bit like lace, but that really touches often times both of your lungs. And that's everywhere. So when you look at it, you really, as a physician, and I'm sure you know that, Brian, you're struck by the extent of pneumonia and yet the patient is in front of you, not that sick. It's really subtle, I would say, in terms of presentation. You have to think about it to find it.

BRIAN GOLDMAN: Now, one thing I do want to say about the signs and symptoms, and that would be the general absence of those signs you mentioned of a virus infection. So things like more of a sore throat, swollen glands around the neck, a runny nose. Am I right?

DR. CAROLINE QUACH: True, although you might be more at risk of developing that pneumonia after that viral respiratory infection. So you might have had that before and then gotten better, and then suddenly you have this. But you're right that typically you don't have all those other symptoms of viral respiratory infections.

BRIAN GOLDMAN: So how much walking pneumonia are you seeing at your hospital?

DR. CAROLINE QUACH: We've seen way more than usual, and that's anecdotal, but also based on our statistics. But since the spring, my colleagues and I have wondered why we were seeing more, and not just more in the emergency department, but also more in the wards. So, patients were admitted with more severe pneumonias than your usual walking pneumonia, but also at times with other manifestations that are not just pneumonia. Because the beauty of that little bacteria -- because it is a bacteria, the mycoplasma pneumoniae -- is that it mimics tons of other things. And so you have to think about it to see if other presentations are actually associated with this bacteria, aside from just coughing.

BRIAN GOLDMAN: You can get diarrhea with it, can't you?

DR. CAROLINE QUACH: You can, but you also can get an inflammation of your brain, which is called encephalitis. You can-- your pneumonia can also be complicated by a need for oxygen supplementation because your level of oxygen, your blood is not high enough. You might also have what we call Stevens-Johnson or a manifestation of the skin that is actually quite extensive, with lesions that can even extend to your mucosal surfaces. So, mouth, eyes, your urinary and genital area. So it might be quite systemically involving.

BRIAN GOLDMAN: Now, you mentioned that you've been seeing cases at your hospital anecdotally since the spring. I know the Centers for Disease Control in the United States has traced this back to March of this year. And it begs the question, how well do we monitor for walking pneumonia and the bacteria that causes it here in Canada?

DR. CAROLINE QUACH: Yeah, so that's a great question. In fact, it's not a disease that is reportable. Therefore, we don't have statistics at the provincial or the federal level. The only thing we can rely on is to look at our percentage of positivity in our labs. So it is diagnosed by a PCR. You know, the same way as we diagnose viruses and pertussis. And so when you ask for PCR for mycoplasma pneumoniae, you can see what percentage of your tests are positive, a little bit like we were following COVID or influenza and RSV every year, and then see that it actually increases compared to previous years. But that really relies on each lab doing it and not having a central repository to see what's happening across the country or even in a single province.

BRIAN GOLDMAN: That's an impediment to getting on top of what's going on as quickly as possible, isn't it?

DR. CAROLINE QUACH: Yeah. So let's say that you'll have less of your finger on the pulse than you would have for influenza, RSV or COVID. I think it's because previously it was hard to diagnose. Only a handful of labs could test it. Or you could ask for, you know, a serology, see if your IgMs -- the antibody that you produce acutely to an infection -- were elevated. But it was always a little bit lengthy before you would get the result. But now that we have, at least most of us, have a BioFire in our lab or in-house PCRs that are usually able to detect it, we're able to test that. Like, just as we would ask for a viral respiratory PCR. And so we have a lot more data nowadays than we had three or four years ago, when the last spike of mycoplasma pneumoniae occurred.

BRIAN GOLDMAN: Why are cases on the rise in the past few months, and especially now?

DR. CAROLINE QUACH: You know, we have to realize, like with everything else, mycoplasma pneumoniae is cyclical, so every three to seven years you have this spike. Potentially because we haven't seen it for a while and so there's a bunch of us that are susceptible to it. A little bit like what we've seen with pertussis or what we saw last year with RSV in children. So if you haven't been exposed, you know, there's this cohort effect that happens. But when we look at our data at Sainte-Justine -- my colleague, Maude Paquette, sent me the data over the past few years -- we had a spike in 2015, another spike in 2019 because of COVID and the measures that were put in place. We haven't seen anything since 2020, right? Because if you do 2019 plus four, that's 2023. So, we almost are there at the three-, four-year mark. And so we've started seeing it now. It's really this cyclical appearance. I think that on top of it, because Quebec had this increase in number of pertussis cases, a lot of the coughing children were tested for pertussis. And at Sainte-Justine and in most of the labs, pertussis and mycoplasma pneumoniae is a multiplex PCR that come hand in hand. And so you think it's pertussis and in the end it's mycoplasma pneumoniae, so you diagnose it and so you start looking for it. And so it's a little bit of both. So there's this bias of detection because we're looking for it more, but there's also this cyclical pattern where we were due to have that spike.

BRIAN GOLDMAN: I want to ask you as well about a theory that has been popularized in social media, even if it's not true. This notion that somehow there is a large swath of kids who are now more susceptible to walking pneumonia simply because they've been wearing masks. Can you address that, please?

DR. CAROLINE QUACH: So, for sure, if you're wearing a mask and if others are wearing a mask, there's a decreased likelihood of transmission of everything. I think that what happened is that because we were protecting ourselves against COVID, we weren't exposed to other viruses and bacteria, which, for a while, was perfect. Now, instead of having just like that, say, two to three years of people who hadn't seen it because it wasn't around, we have a little bit more children and adults who haven't seen it and now are susceptible to it. Whether or not it actually increases severity, I don't think so. It's just an increased number of cases because we have a cohort who haven't been exposed. So it's not because they're more fragile, I would say. It's just that they haven't seen it. So if you go, let's say, in a country where there are no varicella, for instance -- I'm just taking that example -- we know that varicella is not very well transmitted in the southern countries because it's warm and the virus doesn't survive well in the heat. So when these people come to a country where there is still varicella, they are going to be exposed and will get infected. The reason why they catch it now is that now they see it. But it's not because they haven't seen it before that it's going to be more severe now -- except if they're much older. But aside from that, I don't think that the fact that we were wearing masks increased the severity of what we've seen. It's just increasing the number of cases at this point in time. But we've seen this with the various respiratory viruses in the previous years. We are going to come back to a point of balance. We're just getting there.

BRIAN GOLDMAN: And varicella is, of course, the virus that causes chickenpox.

DR. CAROLINE QUACH: Yes, absolutely.

BRIAN GOLDMAN: So you're talking about people, individuals who live in southern climes where chickenpox viruses don't spread around. Unless, of course, they've been vaccinated. If they haven't been vaccinated, and then they come to a northern hemisphere country that has a higher prevalence of chickenpox, they may be more likely to get it. And then we would look at those people and say, oh, well, their-- something weird is going on with their immune system. When, in fact, they had just never been exposed to chickenpox before and now they're getting it because now they're being exposed to it. I see.

DR. CAROLINE QUACH: Yeah, absolutely.

BRIAN GOLDMAN: But the important point is that there is no credible connection between prior COVID infection and walking pneumonia.

DR. CAROLINE QUACH: No, absolutely not. In fact, it was interesting. My PhD student was looking at that. We have a cohort of health-care workers who were infected with COVID, and so we're following them every two weeks since 2021. What we've seen is that people who had COVID before were not more at risk of getting anything in terms of respiratory infections than those who were not infected, except for the fact that those who had children less than five were more likely to be infected. And so that-- we all know that children are the source of most viruses coming home because they are exposed in daycare.

BRIAN GOLDMAN: Which leads me very nicely to my next question. Where are kids primarily acquiring mycoplasma, which causes walking pneumonia? How are they getting it?

DR. CAROLINE QUACH: So this bacteria is spread by droplet mainly, which means that if I have it in my throat and I cough it out and you're within one or two metres from me and it lands in your throat, you're going to catch it. So of course, if you're in environments where it's crowded, like school or daycare or other community events that are happening inside, you're more likely to catch it there.

BRIAN GOLDMAN: When you have walking pneumonia, you're not necessarily sick enough to be admitted to hospital. But this can be a serious illness. Why should we be concerned about walking pneumonia?

DR. CAROLINE QUACH: A for physician for thinking about it and asking for the test, but for parents and young adults to also consult when they think that they might have a pneumonia. Because there are treatments. It is a bacteria, so we have an antibiotic that actually works to treat it. And because, as we were saying before, we can see complications from this mycoplasma pneumoniae. And if you don't think about it, you're not going to address it appropriately and not necessarily treat it the right way. We've seen this year more encephalitis than we've seen before, and we've seen more Stevens-Johnsons or cutaneous manifestations of this mycoplasma pneumoniae than we've seen before. But on top of treating the symptoms, you also have to treat the bacteria to try and decrease the load, and so the antigens present and everything that happens around the infection. So, mainly to treat appropriately the infection.

BRIAN GOLDMAN: The Stevens-Johnson syndrome, severe rash and involvement of what you called the mucous membrane. So inside the mouth, the nose.

DR. CAROLINE QUACH: The eyes.

BRIAN GOLDMAN: The eyes. And sometimes even the urethra.

DR. CAROLINE QUACH: Yeah, absolutely. And that's highly uncomfortable. Dermatologists and pediatricians and internists are going to treat it symptomatically. But again, if you know that there's a mycoplasma involved underneath it, you're going to treat it, hoping to decrease the impact of that bacteria on the rest of your immune system response.

BRIAN GOLDMAN: Caroline, does the prompt use of the right antibiotic help prevent those complications that you talked about, encephalitis and Stevens-Johnson syndrome?

DR. CAROLINE QUACH: Well, we don't know that because we don't have good randomized controlled trials where people were able to be treated early enough to prevent them. Usually, we find these patients because they've already had their encephalitis or their Stevens-Johnsons or whatever else. And then we go back and we try and look and we find the mycoplasma pneumoniae. Their initial mycoplasma was so mild that it's almost impossible to treat it before those manifestations occur. I have to say, I can't really give you a straight answer to that one.

BRIAN GOLDMAN: But certainly, this is a treatable condition with antibiotics, and so the sooner you make the diagnosis, the sooner you put the patient on the right antibiotic and the sooner they get better. Us physicians diagnose walking pneumonia, as you've already mentioned, with a chest X-ray. When should patients and parents of kids be asking for a chest X-ray?

DR. CAROLINE QUACH: I think if you have problems breathing, if you are walking and you're out of breath, which is not usually the case, if you have a lingering fatigue, you know, that lasts more than your usual respiratory viral infection, then see your primary physician. And it's an easy test to do. We usually listen to lungs with our stethoscope. Usually the auscultation will not be perfectly right. And so that is another step moving forward to an X-ray. But I've always said it. I think parents are great knowing their children. There's no one better than us to know when our little ones are not well. So if there's something that is bothering you, just ask.

BRIAN GOLDMAN: What are the front-line antibiotic treatments for walking pneumonia?

DR. CAROLINE QUACH: So usually it's a macrolide, so azithromycin or clarithromycin. Azithro is a five-day course, and it doesn't taste that bad. In fact, it tastes good, so it's not complicated to give it. What's another piece of the puzzle that's missing recently is that we don't have an easy way to know which bacteria is resistant to macrolide. So in China and Asian countries, they have up to 40 to 50% resistance to macrolide. The U.S. is somewhere in the realm of 12 to 15%. But we haven't had any recent data in Canada, not since 2014 or so, where our resistance rate was 11%. So I think we have to also put in place PCR tests to be able to detect resistance gene, because the beauty or the mystery of that bug is that it's a bacteria, but it doesn't have a membrane. So when you put it on a plate, it doesn't grow. And so if it doesn't grow, I'm not able to do my regular antimicrobial susceptibility testing. And so I can't tell you if your bug is resistant or not to your front-line antibiotic. So most of us, what we do is that we start with a macrolide and then if we see that the patient is not improving within a few days, we'll change it either to a fluoroquinolone or tetracycline. But, you know, we have to keep monitoring our patients to make sure that they're actually improving. And I think one key point for treatment is that your first-line treatment for your usual pneumonia -- which is amoxicillin in pediatrics -- doesn't work at all on that bacteria, which is intrinsically resistant to that line of antibiotic.

BRIAN GOLDMAN: Caroline, I think, you know, a lot of people listening to this might be surprised to know this is just usual business for physicians, that when we start a patient on an antibiotic, we're treating them almost always on spec. We're guessing what the right antibiotic will be. It's an educated guess, and it's a reminder that the first choice of antibiotic that we prescribe may not be the right one. So we have to be vigilant and our patients have to be vigilant if they're sick. If they're not getting better, say, within 48 hours and in fact getting sick or more short of breath, that they should seek attention from a health-care provider to get back on the right track.

DR. CAROLINE QUACH: Absolutely.

BRIAN GOLDMAN: Finally, how can we best protect ourselves against walking pneumonia?

DR. CAROLINE QUACH: Well, that's complicated, because the other crux in this particular cute little bug is that the incubation period is really long. So for a virus, somebody coughs on you -- three days later, or almost, you're going to be sick. Or if you're not sick, then you're just, you know, you've escaped it. For this particular bacteria, the incubation period can be up to four weeks. So you don't even realize that you were infected until sometimes a month later. So it's really hard to protect yourself against something that is so sneaky. I think that, you know, the basic prevention measures. So if you're sick and you have a fever, try and stay home. If you're coughing a lot, try to wear a mask so that you're not coughing on everybody. Ensure that wherever you are has a good ventilation system. I mean, we're coming back to what we've learned during the pandemic. And hopefully most public places have learned from those lessons and have implemented those measures. You wash your hands because, you know, you never know what you're coughing up. It could be a virus that's going to be transmitted as well through contact. Mycoplasma doesn't survive that well on surfaces, but still, washing your hands is a basic preventive measure. So, it's nothing more or less than your usual preventive measures. But there's no vaccine. There's nothing magical to prevent mycoplasma pneumoniae.

BRIAN GOLDMAN: Dr. Caroline Quach, thank you so much for educating us on walking pneumonia.

DR. CAROLINE QUACH: Thank you very much.

BRIAN GOLDMAN: Dr. Caroline Quach is a pediatric microbiologist, epidemiologist and infectious diseases specialist. She's a professor in the Université de Montréal Faculty of Medicine and Medical Lead in the Infection Prevention and Control Unit at CHU Sainte-Justine. Here's your dose of smart advice: Walking pneumonia is the informal name for patients who have mild symptoms of pneumonia. The cause is a bacterium called mycoplasma pneumoniae, and the disease mainly affects children and teens, and to a lesser extent, young adults. Walking pneumonia is not a reportable disease in Canada, but anecdotally, we've seen a spike of cases in Quebec, Ontario, Nova Scotia and B.C. The U.S. has also seen an increase in cases since the spring. The U.S. Centers for Disease Control say they've tracked an increase in cases involving kids ages 2 to 4, which is unusual. Experts aren't sure why cases have increased recently. The disease tends to be cyclical, which means there is a predicted spike in cases every 5 to 7 years. Another hypothesis is that there is a large number of kids and teens who are susceptible because they haven't been exposed to the infection until now. The typical symptoms include fever, cough, malaise and fatigue. Other symptoms include diarrhea. Roughly a third of patients get respiratory distress. The disease has two serious complications. One is encephalitis or inflammation of the brain. The other is called Stevens-Johnson syndrome, which is a severe skin rash that may involve the insides of the mouth, nose, eyelids and urethra. The infection generally responds well to an antibiotic called azithromycin. With proper treatment, most patients recover quickly. Seek immediate attention if you or your child has severe respiratory distress. To help prevent the spread of walking pneumonia, follow the general rules for COVID and flu. If you have a fever, stay home from work or school. Wash hands frequently. If you're coughing, wear a mask. If you have topics you'd like discussed or questions answered, our email address is thedose@cbc.ca. If you like this episode, please give us a rating and review wherever you get your podcasts. This edition of The Dose was produced by Sameer Chhabra, with help this week from Jennifer Warren. Our senior producer is Colleen Ross. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health-care provider. I'm Dr. Brian Goldman. Until your next dose.

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What do I need to know about walking pneumonia? - Transcript

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