Clinical Features and Complications

Clinical features

Chlamydia pneumoniae infections can occur in the upper or lower respiratory tract. Clinical presentations can vary widely. The incubation period is generally between 3 to 4 weeks; however, studies have documented shorter times.

People with C. pneumoniae infection most commonly present with cough, fever, headache, and malaise and can develop:

  • Laryngitis
  • Pharyngitis
  • Coryza
  • Pneumonia

After gradual illness onset, symptoms due to C. pneumoniae respiratory infection may continue over extended periods. Patients may experience a persistent cough and malaise for several weeks or months despite appropriate antibiotic therapy.

Clinical complications

Most respiratory infections caused by C. pneumoniae are asymptomatic or mild, although severe complications can occur. These severe complications can result in hospitalization and sometimes death. Complications include:

  • Exacerbation of asthma
  • Encephalitis
  • Myocarditis


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  • Mordhorst CH, Wang SP, Grayston JT. Outbreak of Chlamydia pneumoniaeinfection in four farm families. Eur J Clin Microbiol Infect Dis. 1992;11(7):617–20.
Page last reviewed: November 15, 2021