While the term walking pneumonia sounds dangerous, it is actually a relatively mild form of pneumonia and is the less serious form of pneumonia. Pneumonia can be caused by a variety of factors including chemicals, bacteria, fungi, viruses and mycoplasma, the primary cause of walking pneumonia is attributed to a bacteria called Mycoplasma pneumoniae. The symptoms of walking pneumonia typically occur within 15-25 days after a person has been exposed to this bacteria and the symptoms include sore throat, fatigue, mild fever, chills and a cough.