Walking Pneumonia in Children

Pneumonia is a serious and potentially life-threatening lung infection. A germ called Mycoplasma pneumoniae is often responsible for a milder type of pneumonia called "walking pneumonia." Its victims may feel unusually tired and run down, but they may not realize they have pneumonia and continue about their business.

Facts about Mycoplasma pneumoniae

About 2 million Mycoplasma pneumoniae infections occur each year in the U.S. About 5 to 10 percent of those infections turn into pneumonia. As many as 100,000 people each year are hospitalized because of it. Mycoplasma pneumoniae bacteria can also cause bronchitis and a number of upper respiratory tract infections.

Mycoplasma pneumoniae is quite contagious. It can spread between people through bodily fluids, including phlegm that is coughed up. It can also spread through airborne droplets from sneezing and coughing. It is most easily spread among people who are in close contact with one another. This includes those living within households, military barracks, camps, and college dorms. Mycoplasma pneumoniae infections can spread through whole communities as well.

Mycoplasma pneumoniae is extremely common in school-aged children. It's the most common cause of pneumonia in this age group. But these infections are rare in children younger than 5 years old.

Although Mycoplasma pneumoniae infections can occur at any time of year, they are  most common in the late summer and fall.


Mycoplasma pneumoniae infections can cause a number of symptoms:

  • Fever, which can be high

  • Fatigue

  • Headache

  • Skin rash

  • General feeling of sickness

  • Cough, particularly one that progresses from a dry cough to a productive cough

  • Ear infections

  • Croup

  • Sinus infection

  • Sore throat

Children who have reactive airway disease may suffer from wheezing as a result of the infection.

Symptoms may appear anywhere from one to four weeks after exposure to the bacteria and may last from a week to a month.

Diagnosis and treatment

Special diagnostic tests are being developed to for Mycoplasma pneumoniae bacteria. But they're not yet widely available to the general public. Doctors can diagnose the infection based on symptoms and a chest X-ray. Blood work can identify antibodies to the bacteria.

Often, mild respiratory infections, such as upper respiratory infections and bronchitis, clear up on their own and don't require treatment with antibiotics. But when symptoms are more severe and pneumonia or ear infections develop, antibiotics such as doxycycline, erythromycin, azithromycin, or clarithromycin may be prescribed.


No vaccine is available to prevent a Mycoplasma pneumoniae infection. Practicing good hygiene can help. This includes teaching kids to cover their nose and mouth when they cough or sneeze and to frequently wash hands. These measures can help prevent other infections, too.

What else you need to know

Mycoplasma pneumoniae infections are rarely serious. They respond well to antibiotic treatment, and they typically clear up even without treatment. Deaths are most common in older adults or in people with other health conditions, including sickle cell disease.

People who have already had a Mycoplasma pneumoniae infection do develop some immunity. But this usually doesn't last for a lifetime. A second infection from the bacteria is possible, but the illness is likely to be a milder version. 

To request an appointment with a physician at St. Louis Children's Hospital, call 314.454.5437 or 800.678.5437 or email us.