Fast Facts

  • Chlamydia pneumoniae are a type of bacteria that can infect the upper and lower respiratory tracts.
  • C. pneumoniae can spread when infected people cough or sneeze while in close contact with others, who then breathe in the bacteria.
  • Most people with C. pneumoniae infections have mild illness or do not have symptoms at all. Although some people can develop a serious lung infection (pneumonia), particularly older adults.
  • Symptoms of a C. pneumoniae infection usually start gradually. It can take someone 3 to 4 weeks to get sick after breathing in the bacteria.
  • After gradual onset, symptoms due to C. pneumoniae infection may continue for several weeks or months even with appropriate antibiotic treatment.
  • Since C. pneumoniae infection is likely underdiagnosed, the actual number of cases each year is unknown.