Walking pneumonia is a very common type of respiratory illness, with an estimated 2 million cases annually in the United States, caused by Mycoplasma pneumoniae. The mycoplasmas are the smallest known free-living bacteria and are unique because they lack a cell wall.

Stethoscope Public domain image/Darnyi Zsóka
Public domain image/Darnyi Zsóka

“Walking pneumonia” is an atypical pneumonia and gets its name from the fact that people infected can usually go through their day doing the things they normally do, unlike the more severe, traditional types of pneumonia.

Mycoplasma pneumoniae is found worldwide and can be seen in epidemics like in military populations. Outbreaks also occur in schools and households. It typically infects people age 40 and younger. Some studies suggest that this organism causes up to 50% of all pneumonias.

People get infected likely through droplet inhalation (by respiratory means) and direct contact with infected people.

Symptoms of “walking pneumonia” are gradual in onset. Headache, malaise, fever, cough, sore throat and shortness of breath are some common symptoms. Ear and eye pain, and a rash are sometimes experienced.

In more severe cases, the pneumonia may progress from one lobe to the other. Hemolytic anemia, serious pneumonia and central nervous system complications like encephalitis are rare but can occur.

Most cases of Mycoplasmapneumoniae are self-limiting and do not require antibiotic treatment. However, without antibiotic treatment, you may feel sick for a month or more. Because Mycoplasma pneumoniae lacks a cell wall, it cannot be treated with penicillins. To shorten the course of illness or for more serious infections, effective treatments are erythromycin, clarithromycin and azithromycin.