title: Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000.
abstract: OBJECTIVE
  To identify risk factors for infection and severe illness due to Chlamydia pneumoniae.
  
  
  METHODS
  To identify risk factors for infection, we conducted a case-control study among nursing home residents who had onset of symptoms during December 1, 1999, to February 20, 2000. To identify risk factors for severe illness among nursing home residents, we conducted a retrospective cohort study.
  
  
  METHODS
  A nursing home providing long-term and day care services for elderly patients in Japan.Participants. Fifty-nine residents and 41 staff members of a nursing home.
  
  
  RESULTS
  The attack rates for respiratory illness were 53% (31 of 59) among residents and 22% (9 of 41) among staff. Infection was confirmed in 15 resident and 2 staff case patients by isolation of C. pneumoniae from nasal swab specimens. Fifteen resident case patients developed severe illness (ie, bronchitis, pneumonia, and hypoxia); one case patient died. The median age of resident case patients was 87 years. We could identify neither the source of the outbreak nor significant risk factors for infection and severe illness in residents. However, residents with a higher level of physical activity were more likely to become infected, whereas older residents (aged more than 85 years) and those with a lower level of physical activity were more likely to develop severe illness (P>.05). Contact with residents was a risk factor for infection in staff (relative risk, undefined; P=.04).
  
  
  CONCLUSIONS
  C. pneumoniae can cause large outbreaks of infection and severe illness among elderly persons, and its transmission is likely to be enhanced by close contacts among people in nursing homes. Therefore, early detection of an outbreak by means of better surveillance, and subsequent isolation of patients, may be effective control measures.
authors.affiliation: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Toyama, Shinjyuku, Tokyo, Japan. knakashi@nih.go.jp
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Nakashima
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Michael H
authors.initials: MH
authors.lastname: Kramer
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Takaaki
authors.initials: T
authors.lastname: Ohyama
authors.forename: Toshio
authors.initials: T
authors.lastname: Kishimoto
authors.forename: Hironori
authors.initials: H
authors.lastname: Toshima
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Miwa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nomura
authors.forename: Naoki
authors.initials: N
authors.lastname: Tsumura
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Ouchi
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Okabe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000382:microbiology / Q000503:physiopathology; D016993:Chlamydophila pneumoniae / Q000302:isolation & purification*; D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009735:Nursing Homes; D012307:Risk Factors; D012720:Severity of Illness Index