title: Chlamydia pneumoniae infection predicts a reduced risk for subsequent atopic disease.
abstract: OBJECTIVE
  To investigate long-term effects on children previously infected with Chlamydia pneumoniae.
  
  
  METHODS
  A follow-up questionnaire was sent to all participants from a former population-based study in order to investigate health status during the 4 y that had elapsed between the two studies. In the original study, the prevalence of C. pneumoniae infection was 23% as determined by PCR analyses on throat swab specimens. These PCR results were found to have no detectable correlation for clinical disease. The main outcome measures in this follow-up study were the reported prevalence of respiratory tract infections, asthma and allergy.
  
  
  RESULTS
  Approximately 83% completed the follow-up questionnaire. No increase in respiratory tract infections was reported by children previously found to have C. pneumoniae infection. A diagnosis of allergy was more common in the former PCR-negative population (13.4% vs 4.7%, p<0.03). The differences were most apparent in the population with atopic heredity. In a logistic regression model with different suggested risk factors for allergy, earlier infection with C. pneumoniae reduced the risk for allergy (OR=0.13; 95% CI: 0.02-0.99). This was not found for asthma.
  
  
  CONCLUSIONS
  A positive PCR test for C. pneumoniae in young children was associated with a lower risk of developing allergic airway disease in this study population, and did not predict an increase in respiratory tract infections.
authors.affiliation: Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada. erik.normann@kbh.uu.se
authors.forename: Erik
authors.initials: E
authors.lastname: Normann
authors.forename: Judy
authors.initials: J
authors.lastname: Gnarpe
authors.forename: Håkan
authors.initials: H
authors.lastname: Gnarpe
authors.forename: Björn
authors.initials: B
authors.lastname: Wettergren
mesh_terms: D001249:Asthma / Q000453:epidemiology; D002648:Child; D002690:Chlamydia Infections; D016993:Chlamydophila pneumoniae; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012130:Respiratory Hypersensitivity / Q000453:epidemiology*; D012141:Respiratory Tract Infections / Q000453:epidemiology; D012307:Risk Factors; D011795:Surveys and Questionnaires