The temperature is dropping, and rates of a whole host of respiratory illnesses are doing the opposite. Among them is so-called walking pneumonia, a relatively mild form of pneumonia that has been unusually common in young children this year.
Pneumonia can be caused by dozens of different pathogens, but walking pneumonia is most commonly caused by a bacterium called Mycoplasma pneumoniae. Traditional pneumonia can require hospitalization. Walking pneumonia, however, can feel like a bad cold and is sometimes not even serious enough to force people to rest at home. This year experts are particularly concerned about the infection because it appears more prevalent than usual in young children. According to the Centers for Disease Control and Prevention, this past October, about 7 percent of children and adolescents between two and 17 years old who had pneumonia-related emergency room visits were diagnosed with a M. pneumoniae infection. The proportion of M. pneumoniae cases increased between March and October, and the increase was higher in children between two and four years old than it was in older children. That is especially striking because, traditionally, infections have been highest among children between age five and 17.
Scientific American spoke with Eberechi Nwaobasi-Iwuh, a pediatric hospitalist at Atlantic Health System’s Morristown and Overlook Medical Centers in New Jersey, about walking pneumonia trends and what parents should know.
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[An edited transcript of the interview follows.]
What is walking pneumonia?
The reason it’s referred to as walking pneumonia is that you can be infected with Mycoplasma and develop pneumonia from it, and even though you have pneumonia, you won’t have the typical symptoms. You may have some fatigue and fever and cough, but it doesn’t make you typically as ill as one would expect from pneumonia. That said, recently we’re seeing some kids who are coming in who are fairly sick with it.
How would you characterize walking pneumonia rates this year compared with previous years?
Usually it’s more common in school-aged kids, adolescents and young adults, but this year we’re seeing it in very young children and even infants. Sometimes they may be symptomatic, or sometimes we’re just catching it when we’re swabbing them for microbes with other presentations. We’re just seeing it distributed more widely across more age groups than we typically do.
Are there also more cases this year than usual, or is it just that unusual age pattern?
Oh, definitely more cases. In my experience, we’ve probably seen a two- to threefold increase in the number of cases you ordinarily see for this time of year.
Are there any theories about what’s driving the age shift, with more young kids getting sick?
Since COVID, all the regular seasonal variations with viruses and bacteria really don’t follow the same patterns they used to. Some degree of decrease in immunity may have occurred, or the cause may be a more virulent strain that’s just a little bit more transmissible than usual. But I think it’s kind of hard to say what exactly is spurring the age shift.
Some viruses have episodic increases, so every five to seven years, you’ll see an increase in cases. Mycoplasma bacteria also follow that pattern sometimes, so this may just be the typical increase that we would have expected overall, historically.
How seasonal is walking pneumonia in general?
Usually it’s more common during the fall and winter months, but even in August we started seeing somewhat increased cases, and that’s continued. Even during the early summer and late spring we were seeing some Mycoplasma, but it was manifesting differently.
How do experts diagnose walking pneumonia?
The only way to really track it is if you get tested for it, but not every pediatrician or physician office is going to have the ability to test for it. A lot of physicians will be able to see a patient and, based on their symptoms and how long they’ve been sick and if they have been on other antibiotics beforehand and not improved, be able to say, “It’s probably Mycoplasma; I’m just going to treat you [for it].”
What are the symptoms of walking pneumonia?
A lot of times, you’ll have respiratory symptoms—so sore throat—but not much nasal congestion. But now we’re seeing a lot of kids with rhinorrhea—congestion and a runny nose—sore throat, chest pain, some fatigue, poor appetite. That can progress to difficulty with breathing. It’s usually kind of consistent with cold symptoms that don’t really get better, that may progress and worsen. For most colds, usually you’re going to have symptoms for maybe five, seven days, and then you’re going to get better or worse. It’s definitely important to see your doctor if you have symptoms that are nagging after about five to seven days or worsening after that time period.
Mycoplasma can also cause inflammation of the lining around the brain. You can have encephalitis [swelling of the brain]. You can also have mucositis [swelling of the mucous membrane lining your mouth and intestinal tract] and a rash, where you can get sores in the mouth, on the lips, and some redness and sores on the skin and around the eyes.
What should parents look for, and when should they call their doctor?
If you feel you child is sick with respiratory symptoms, fever, not eating well, not urinating as much as they should be or even just has really prolonged cold symptoms that aren’t getting better after five to seven days, that’d be a reason to call their pediatrician and have them checked out. Even before that five-to-seven-day mark, if your child is worsening to the point that they’re not able to eat and drink, they’re not behaving like themselves or they’re working harder to breathe, those are all indications to call the pediatrician as well.
What treatments are available for walking pneumonia?
Typically, Mycoplasma is treated with an antibiotic called azithromycin, or a Z-Pack [Zithromax]. Most people get better after treatment with that for about five days. In very rare instances, if someone doesn’t get better, there are additional antibiotics one can give.
In addition, if you’re hydrated and well rested, you’ll be able to get through any illness better; if you're dehydrated and fatigued, your immune system will be less robust in helping you fight things off. So if you start feeling sick, getting more rest, keeping hydrated, eating as much as you’re able to keep your nutrition up all definitely help.
Are there any ways people can avoid catching it in the first place?
If you are really concerned or will be in crowded places, you could definitely wear a mask. Hand washing is always one of the best, most effective and consistent way to prevent infection. Avoid touching your face when you’re out and about—that’s usually one of the most direct ways people get sick. And then, most importantly, if you’re feeling ill or sick, you should try to avoid going out and infecting other people.
How long should we expect walking pneumonia to be circulating?
It’s hard to say. Most respiratory illnesses start increasing around late September or October, pick up through the winter months, and usually start ramping down around early to mid-March. It’s very possible we may see the same thing with Mycoplasma as we see with respiratory syncytial virus (RSV) and the flu and other respiratory illnesses.
What will you be watching for in the coming weeks?
Right now, in hospitals, we’re seeing some sick kids, but a lot of children are being treated on an outpatient basis and getting better. I think if you start to see high numbers consistently, that would be a little concerning. But again, Mycoplasma is a fairly self-limited illness for most people: once they get started on the right antibiotics, they get better fairly rapidly. I think as long as we still see that pattern, we’re okay.
Is there anything else you want people to know about walking pneumonia?
It’s a very well-known bacterium that causes illness in kids and adults, and there are good treatments for it. Be aware of it, and if your child is sick and not getting better, have them evaluated for it clinically by their pediatrician. But for the most part, most kids will get better, even if they don’t get treated for it. So I don’t think there’s a reason to be excessively worried about it.