An epidemic of infections due to Chlamydia pneumoniae in military conscripts.

A prospective observational study of an epidemic of infection due to Chlamydia pneumoniae strain TWAR in Finnish military trainees provided new information on immunity following infection, the range of clinical syndromes and complications, and cell culture isolation. One-half of the trainees studied (43 of 86) had laboratory evidence of C. pneumoniae infection. The etiologic association of C. pneumoniae with disease was strengthened by the sharp increase in cases of pneumonia and in outpatient visits for acute respiratory disease along with the laboratory evidence of infection. The pattern of serological response suggested that 23 of the trainees had a primary TWAR infection and 20 had a reinfection. Evidence that prior infection modified the illness included the frequency of hospitalization (12 with primary infections vs. 1 with reinfection), the development of pneumonia (10 vs. 0), and the requirement for repeated courses of antibiotic therapy (13 courses vs. 0). Isolation was more frequent in HL cells (n = 25) than in HeLa 229 cells (n = 10).