Chlamydia pneumoniae Infection Surveillance and Trends

Key points

  • There is no national reporting or surveillance system for Chlamydia pneumoniae infections.
  • The true number of people affected by C. pneumoniae infections each year is unknown.
  • Many C. pneumoniae infections aren't identified due to mild illness or lack of symptoms and infrequent laboratory testing.

Data sources

C. pneumoniae infection isn't a nationally notifiable condition. There are no surveillance systems to collect information about cases. However, studies and outbreak investigations provide helpful information.

Studies

Most estimates of the impact of C. pneumoniae come from studies looking at the causes of community-acquired pneumonia. Community-acquired pneumonia is a term for when someone develops pneumonia in the community (not in a hospital).

C. pneumoniae often cause mild illness so many people don't seek care for it. In fact, some people who are infected don't have any symptoms. Thus, studies based on people with community-acquired pneumonia likely underestimate true cases of C. pneumoniae infection.

A large-scale U.S. study of community-acquired pneumonia requiring hospitalization found C. pneumoniae was a rare cause of infection in children and adults.12

Outbreaks

Outbreaks occur mostly in crowded environments including:

  • College residence halls
  • Detention or correctional facilities
  • Hospitals
  • Long-term care settings
  • Military training facilities
  • Schools

Outbreaks may last a long time for several reasons. First, people without symptoms can spread the bacteria. This includes during the 3- to 4-week-long incubation period (time between exposure and start of symptoms). Second, since C. pneumoniae infections are generally mild, people usually don't need treatment but can be contagious for several weeks after symptoms start.

Outbreaks of C. pneumoniae infection are primarily controlled by common infection control and prevention measures, including handwashing.

Trends

People can get sick any time of the year. There isn't a particular season when people are more likely to get a C. pneumoniae infection.

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Content Source:
National Center for Immunization and Respiratory Diseases; Division of Bacterial Diseases
  1. Jain S, Self WH, Wunderink RG, et al. Community-acquired pneumonia requiring hospitalization among U.S. adults. N Engl J Med. 2015;373(5):415–27.
  2. Jain S, Williams DJ, Arnold SR, et al. Community-acquired pneumonia requiring hospitalization among U.S. children. N Engl J Med. 2015;372(9):835–45.