Evolution of legionnaires' disease in an urban hospital - abstract

ABSTRACT

Ongoing epidemiological surveillance for nosocomial Legionnaires' Disease (LD) was initiated after control of an initial outbreak involving eight cases at a Nova Scotia Hospital in 1984. All cases of nosocomial pneumonia were screened for LD, and water samples were cultured for Legionella at intervals. No clinical cases of LD were identified until April, 1987, although there were occasional positive cultures from water samples in different areas of the hospital. Subsequently, six to seven cases have been identified over each 12-month period with no more than two cases in any month. The mean age of patients was 67.7 years (range 54 - 83) with a male to female ratio 2.51. The mean time of onset of pneumonia after admission was 19.9 days (range 8 - 27) with diagnosis being made in most cases by sputum culture. Risk factors included smoking, immunosuppressive therapy and admission to a specific wing of the hospital. Water samples from the specific wing of the hospital were persistently positive at high levels until certain plumbing revisions were instituted. In contrast to the initial outbreak, these cases represent an endemic level of nosocomial LD related to a specific area of the hospital. Ongoing surveillance is required for detection and control (AU)