The incidence of Chlamydia pneumoniae lower respiratory tract infections among university students in northern California.

Chlamydia pneumoniae has recently been identified as a cause of lower respiratory tract infections. From March 1987 to March 1988, 259 university students-151 students with lower respiratory tract infections and 108 controls-from the University of California, Berkeley, were studied to determine the incidence and pattern of C pneumoniae lower respiratory tract infections. Serologic evidence of a recent C pneumoniae infection was found in less than 2%, and the organism was not isolated from any of the subjects. Despite the paucity of evidence of a recent infection, 47.5% of this university population showed serologic evidence of a previous C pneumoniae infection. The lower incidence of C pneumoniae infection in our population, when compared with previous reports, suggests that there may be geographic and temporal differences or fluctuations among populations.