Etiologic Agent Mycoplasma pneumoniae , a small bacterium. Incidence Each year an estimated 2 million cases and 100,000 pneumonia-related hospitalizations occur in the United States. Fatal cases are reported occasionally, primarily among the elderly and persons with sickle-cell disease. Incubation period is 1 to 4 weeks. Risk Groups Persons of all ages are at risk but rarely children less than 5years old.
Outbreaks are common among young adults, especially in crowded military and institutional settings.
Outbreaks in these settings can last several months. No national surveillance system exists. However, with improved diagnostic testing, more cases may be identified. Exploration of the role of M. pneumoniae in community-acquired pneumonia and as a potential cofactor in severe pneumonia.