title: Chlamydia pneumoniae as a new source of infectious outbreaks in nursing homes.
abstract: OBJECTIVE
  To determine the extent and severity of illness and mode of transmission of Chlamydia pneumoniae infection in 3 nursing home outbreaks.
  
  
  METHODS
  Retrospective cohort study in 3 nursing homes in Ontario from September to November 1994.
  
  
  METHODS
  A total of 549 residents and 65 staff members.
  
  
  METHODS
  Morbidity and mortality were determined by a review of disease surveillance forms, residents' charts, and a self-administered questionnaire to staff. Single and paired serum samples for C pneumoniae serological testing and nasopharyngeal swabs for C pneumoniae culture were collected, and direct fluorescent antibody assays were performed to confirm C pneumoniae infection.
  
  
  RESULTS
  The attack rates for confirmed and suspected cases combined were 68%, 46%, and 44% among residents in nursing homes A, B, and C, respectively, and 34% among nursing home C staff. A total of 16 cases of pneumonia confirmed by chest x-ray and 6 deaths were identified. The spectrum of illness among nursing home C residents included a new cough in 58 (100%), fever in 37 (64%), sore throat in 14 (24%), and hoarseness in 8 (14%). Staff members at nursing home C were more likely to report hoarseness (P<.001) and sore throat (P<.001). Residents who smoked had onset of illness earlier than nonsmokers (P=.007), which perhaps is related to airborne transmission in a designated smoking room.
  
  
  CONCLUSIONS
  Chlamydia pneumoniae caused serious morbidity and mortality among residents and morbidity among staff; C pneumoniae is an important cause of respiratory disease outbreaks in nursing homes, and diagnostic tests must be readily available for early recognition of C pneumoniae infections.
authors.affiliation: Ontario Ministry of Health, Toronto, Canada.
authors.forename: C J
authors.initials: CJ
authors.lastname: Troy
authors.forename: R W
authors.initials: RW
authors.lastname: Peeling
authors.forename: A G
authors.initials: AG
authors.lastname: Ellis
authors.forename: J C
authors.initials: JC
authors.lastname: Hockin
authors.forename: D A
authors.initials: DA
authors.lastname: Bennett
authors.forename: M R
authors.initials: MR
authors.lastname: Murphy
authors.forename: J S
authors.initials: JS
authors.lastname: Spika
mesh_terms: D000368:Aged; D002690:Chlamydia Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000635:transmission; D016993:Chlamydophila pneumoniae / Q000302:isolation & purification; D015331:Cohort Studies; D003428:Cross Infection / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000635:transmission; D005260:Female; D019085:Fluorescent Antibody Technique, Direct; D006707:Homes for the Aged / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D009305:Nasopharynx / Q000382:microbiology; D009735:Nursing Homes / Q000706:statistics & numerical data*; D009864:Ontario / Q000453:epidemiology; D012189:Retrospective Studies; D012698:Serologic Tests; D012720:Severity of Illness Index