Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000

Kazutoshi Nakashima, Takeshi Tanaka, Michael H. Kramer, Hiroshi Takahashi, Takaaki Ohyama, Toshio Kishimoto, Hironori Toshima, Shigeyuki Miwa, Atsushi Nomura, Naoki Tsumura, Kazunobu Ouchi, Nobuhiko Okabe

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


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. SETTING. 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.

Original languageEnglish
Pages (from-to)1171-1177
Number of pages7
JournalInfection control and hospital epidemiology
Issue number11
Publication statusPublished - 2006 Nov
Externally publishedYes

ASJC Scopus subject areas

  • Epidemiology
  • Microbiology (medical)
  • Infectious Diseases


Dive into the research topics of 'Outbreak of Chlamydia pneumoniae infection in a Japanese nursing home, 1999-2000'. Together they form a unique fingerprint.

Cite this