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What is Mycoplasma Pneumoniae? 5 Things You Need to Know

Including how to protect yourself from the bacteria that’s a common cause of ‘walking pneumonia’  

spinner image illustration of the human chest with lungs filled with mycoplasma pneumoniae bacterium represented by yellow and green glowing dots on a bright orange background
Eugene Mymrin / Getty Images

A common type of bacteria that can cause pneumonia is making news headlines in the U.S. and abroad due to an uptick in infections among children.

Called Mycoplasma pneumoniae, the germ typically causes a chest cold, with symptoms ranging from a sore throat to a headache. But it can cause more serious illness in kids and adults alike. One study found that Mycoplasma pneumoniae is the second most common bacteria that causes pneumonia in hospitalized adults, according to the Centers for Disease Control and Prevention (CDC).

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Here’s what you need to know about Mycoplasma pneumoniae, a cause of so-called walking pneumonia, including how to best protect yourself from an infection this winter.

1. Mycoplasma pneumoniae isn’t new

Though you may not have heard of it before, Mycoplasma pneumoniae, which can damage the lining of the respiratory system, has been around for decades — scientists identified it in 1944, according to the CDC. Each year, it causes at least 2 million infections in the U.S., though health experts say that number is likely much greater, since many cases go undiagnosed.

2. An uptick in cases isn’t surprising

Andrew Pekosz, a professor of microbiology at Johns Hopkins Bloomberg School of Public Health, says we typically see surges of Mycoplasma pneumoniae every few years — three to seven, according to the CDC — so it’s not unexpected to see one now.  

What’s with all the buzz, then? “I think everybody is a little bit more on edge these days as we look at pneumonias and respiratory illnesses,” Pekosz says. (You may remember that the coronavirus pandemic started in late 2019 with reports of a mystery pneumonia-like outbreak in China.)

But health experts suspect there’s nothing new or mysterious about the pathogens behind increasing cases of pediatric pneumonia reported in some areas of the U.S. and a handful of countries in Europe. “Instead, these increases are likely caused by viruses and bacteria we expect to see during the respiratory illness season,” the CDC said in a Dec. 1 report.

According to a statement from the World Health Organization, the rising rates of pneumonia among children in China appear to be caused by typical bugs such as influenza, Mycoplasma pneumoniae and respiratory syncytial virus (RSV).

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“We’ve actually seen a lot of recurrences of infections that were common before the pandemic that we saw temporarily suppressed to some extent during the time where we were using precautions [and things were shut down],” says Beth Thielen, M.D., an assistant professor and specialist in adult and pediatric infectious diseases at University of Minnesota Medical School.

“With a lot of these infections, the natural history is that you get infected, you get some transient boost in your immunity, and then that immunity wanes over a period of years, and then over time, you’re susceptible until the next time you’re exposed. And so it may very well be that we’re seeing a sort of rebound to some of these infections that people haven’t seen in a few years because of all the COVID precautions,” she says.

3. It can cause a milder ‘walking pneumonia’

Mycoplasma pneumoniae infections are most common in children and young adults, but anyone can be affected, the CDC says. Typically, symptoms are mild and may include a sore throat, headache, fatigue, fever, a cough and sometimes a rash. But Mycoplasma pneumoniae can cause pneumonia, or inflammation of the lungs, and is the most common cause of “walking pneumonia” in the U.S. (Walking pneumonia, also called atypical pneumonia, is a milder form of the disease that usually doesn’t require bed rest, though symptoms tend to be “a little bit more lingering,” Thielen says.)

Sometimes an infection can turn severe and lead to more serious pneumonia, asthma attacks, kidney problems and other health issues. People at higher risk for a severe case of Mycoplasma pneumoniae include those with an underlying lung condition, individuals with a weakened immune system and people who are recouping from a respiratory illness, the CDC says.

Most people recover from a Mycoplasma pneumoniae infection without requiring a prescription from the doctor. However, specific types of antibiotics can be used to treat pneumonia caused by the bacterium.

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4. Staying up to date on vaccines can help  

Like COVID-19, influenza and many other common respiratory illnesses, Mycoplasma pneumoniae is spread through small droplets produced when an infected person coughs or sneezes. This means most of us are already familiar with the actions that can help prevent an infection, such as staying home when you’re sick and washing your hands often. “All the same things hold true,” Pekosz says, referring to COVID-19 and flu precautions.   

Symptoms of Walking Pneumonia

Walking pneumonia symptoms, which can persist for weeks, include:

  • Sore throat
  • Fatigue
  • Chest pain or discomfort
  • Fever
  • Cough
  • Headache
  • Runny nose
  • Ear pain

Source: Cleveland Clinic, Mayo Clinic

Wearing a mask when you’re in a crowded environment can also help reduce your risk. Another thing: Although there’s not a vaccine that can defend against Mycoplasma pneumoniae, getting vaccinated for flu, COVID-19 and RSV can be protective.

“Sometimes people get a viral infection first and then go on to get bacterial infections after. The viral infection sort of opens the door and then lets these bacterial infections in,” Thielen says. Doctors refer to this as a secondary infection. “So I think anything people can do to generally protect the respiratory health and protect themselves from other types of infections that we see this time of year is helpful,” she adds.

Plus, COVID-19, flu and RSV can all cause pneumonia, too. And don’t forget about Streptococcus pneumoniae, or pneumococcus — the most common cause of bacterial pneumonia in the U.S. “And older adults are eligible for that vaccine as well,” Thielen says.

5. Precautions, not panic 

With reports of Mycoplasma pneumoniae cases on the rise, now is not a time to panic, Thielen says, but instead to remember all the precautions that can help protect you from this bug and others circulating this time of year.

“There are some basic techniques that work pretty well against many respiratory pathogens,” Thielen says. “I say do the best you can as much of the time as you can during this high-risk season, and hopefully that’ll bring the burden of disease down for all of us.”

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