title: Chlamydia pneumoniae seroprevalence in immunocompetent and immunocompromised populations in Milan.
abstract: BACKGROUND
  Chlamydia pneumoniae is drawing increasing attention as an agent of respiratory tract infection. Specific antibody prevalence in western countries is low in preschool children and reaches more than 50% in adults. However, little is known about the prevalence of this infection in immunocompromised subjects such as HIV-I infected patients. The aim of this study was to evaluate the seroprevalence of Chl pneumoniae in immunocompetent and immunocompromised (HIV-1 infected) paediatric and adult populations.
  
  
  METHODS
  Between March 1991 and September 1992 764 healthy subjects (421 men and 343 women, age range six months-81 years), 96 HIV-I infected (73 men and 23 women, age range 18-35 years) and 126 HIV-I negative intravenous drug users (92 men and 34 women, age range 18-37 years), and 50 children (23 boys and 27 girls, age range 8-123 months) with vertically transmitted HIV-I infection were studied. For each subject an HIV-I test (ELISA and Western blot) was performed, together with a microimmunofluorescence test for IgG and IgM antibodies to Chl pneumoniae specific antigen (TW-183).
  
  
  RESULTS
  In the healthy population a low prevalence (11%) was observed in children under 10 years of age, which increased progressively to 58% in adults over 70 years. In the HIV-I infected population Chl pneumoniae seroprevalence was higher than in immunocompetent controls (children, 26% v 11%; drug users, 60% v 40%). Moreover, in drug users this difference was also observed in comparison with HIV-1 negative intravenous drug users (60% v 33%).
  
  
  CONCLUSIONS
  Our data on Chl pneumoniae seroprevalence in a healthy population are consistent with those reported by others in western countries. Moreover, HIV-I infected subjects seem to be at higher risk of developing Chl pneumoniae infections.
authors.affiliation: Institute of Respiratory Diseases, University of Milan, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Blasi
authors.forename: R
authors.initials: R
authors.lastname: Cosentini
authors.forename: M C
authors.initials: MC
authors.lastname: Schoeller
authors.forename: A
authors.initials: A
authors.lastname: Lupo
authors.forename: L
authors.initials: L
authors.lastname: Allegra
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000276:immunology; D016993:Chlamydophila pneumoniae / Q000276:immunology*; D005260:Female; D015658:HIV Infections / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D007121:Immunocompetence; D016867:Immunocompromised Host; D007223:Infant; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors