Chlamydia pneumoniae

Clinical Features

Pneumonia or bronchitis, gradual onset of cough with little or no fever. Less common presentations are pharyngitis, laryngitis, and sinusitis. The spectrum of illness can range from asymptomatic infection to severe disease.

Aetiologic Agent

Chlamydia pneumoniae, proposed new name, Chlamydophila pneumoniae. C. pneumoniae is distinct from other Chlamydia species.

Incidence

The overall incidence is unknown. Each year, an estimated 2-5 million cases of pneumonia and 500,000 pneumonia-related hospitalizations occur in the United States.

Sequelae

C. pneumoniae infection may be associated, by some investigators, with atherosclerotic vascular disease. Associations with Alzheimer's disease, asthma, and reactive arthritis have been proposed.

Transmission

Person-to-person transmission by respiratory secretions.

Risk Groups

All ages at risk, but most common in school-age children. In the United States, about 50% of adults have evidence of past infection by age 20. Reinfection throughout life appears to be common.

Surveillance

No national or state surveillance exists.

Trends

Unknown. Improved diagnostic testing may lead to improved recognition of infection.

Challenges

There is a lack of standardized diagnostic methods. Isolation of the etiologic agent is difficult, so antibody tests using paired acute- and convalescent-phase sera have been used for diagnosis. There are no known methods to prevent possible sequelae. The role of C. pneumoniae in atherosclerotic vascular disease needs further definition.

Opportunities

To apply new laboratory methods to develop better diagnostic tests and to evaluate association between C. pneumoniae infection and atherosclerosis, as well as other chronic diseases.

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