Clinical Features

Majority with upper respiratory tract infections with fever, cough, malaise, and headache. May lead to tracheobronchitis with fever and nonproductive cough: radiologically confirmed pneumonia develops in 5-10% of cases; rare extrapulmonary syndromes, including cardiologic, neurologic, and dermatologic findings.

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.

Sequelae

Persistent cough is common during convalescence; other sequelae are rare. Fatal cases are reported occasionally, primarily among the elderly and persons with sickle-cell disease.

Transmission

Person-to-person transmission by contact with respiratory secretions. Incubation period is 1 to 4 weeks.

Risk Groups

Persons of all ages are at risk but rarely children less than 5 years old. It is the leading cause of pneumonia in school-age children and young adults. Outbreaks can occur especially in crowded military and institutional (e.g., college) settings. Outbreaks in these settings can last several months.

Surveillance

No national surveillance system exists.

Trends

Unknown. However, with improved diagnostic testing, more cases may be identified.

Challenges

Diagnosis of acute infections remains difficult; therefore, early recognition of outbreaks has been problematic. Challenge: prevent secondary cases in outbreak by prompt initiation of control measures.

Opportunities

Basic diagnostic strategy in clinical practice includes serology and standard polymerase chain reaction (PCR). New diagnostic techniques (PCR-related methods) may enable more rapid diagnosis. Exploration of the role of M. pneumoniae in community-acquired pneumonia and as a potential cofactor in severe pneumonia.