Walking pneumonia is what it sounds like, a form of pneumonia so seemingly mild that people with the bacterial illness are often up and about—and inadvertently spreading germs. As the disease continues to circulate nationwide this fall, it’s important to take note of its subtle symptoms.
A bacterium called Mycoplasma pneumoniae causes two types of respiratory tract infections: the more common chest cold, tracheobronchitis, and the less common lung infection, walking pneumonia. Though we’re in the thick of respiratory illness season, the bacterium can spread year round. This year infections spiked in late spring and have remained high, the Centers for Disease Control and Prevention (CDC) said in mid-October, with the proportion of emergency department patients discharged with a diagnosis of M. pneumoniae-associated pneumonia or acute bronchitis peaking in August.
Such infections tend to be most common among older children and adolescents but in 2024 have been rampant among young children. The CDC reported the following increases in walking pneumonia emergency department visits, as a proportion of pneumonia-associated visits, from March 31 through the week ended Oct. 5:
Bacterial strain variations generally cause M. pneumoniae infections to peak every three to seven years, according to the CDC. The COVID-19 pandemic, however, interrupted this pattern. After years of low incidence, such bacterial infections reemerged worldwide in 2023.
Pneumonia, which can be bacterial, viral, fungal, or parasitic, comes in many forms. Walking pneumonia is considered atypical, according to Dr. Camille Sabella, a pediatric infectious disease specialist at Cleveland Clinic Children’s.
“Walking pneumonia can be different things. It’s usually not your standard bacterial pneumonia,” Sabella said in an Oct. 28 news release about the uptick in cases. “Walking pneumonia is usually caused by something called mycoplasma pneumonia, but it can also be very similar to viral pneumonias as well.”
M. pneumoniae spreads via respiratory droplets, so covering your mouth and nose when you cough or sneeze goes a long way in preventing others from getting sick. And because there’s no walking pneumonia vaccine, practicing good hygiene including handwashing is the best way to avoid illness, the CDC says.
Walking pneumonia outbreaks typically occur in these crowded locations: