Legionnaires' disease outbreaks--the engineering implications.

Abstract

It has long been known that hepatitis A, salmonellosis, dysentery and other gastrointestinal infections may result from drinking water from contaminated potable supplies. Fortunately it is a rare event for potable supplies to be contaminated in this country but it is a potential hazard, particularly in all those hospitals still supplying drinking water from their own reservoirs or holding tanks. In recent years it has been recognized that cooling waters and domestic water systems in hospitals may also serve as sources of certain infections (B roome, 1984; Bartlett, 1984). Legionnaires’ disease, caused by the bacterium Legionella pneumophila, is one such infection which occurs both in outbreaks and endemically in hospitals Hot water systems have been shown to be the most important source, with the infection being acquired not by ingestion but through the inhalation of water droplets. Other organisms such as Acinetobacter lwofii, Micrococcus varians and Pseudomonas stutzeri, may also colonize hospital domestic hot water systems and produce disease in patients whose normal defences are weakened by illness or treatment (Meers, 1981). In general the prevention of such infections from hospital water systems depends on the maintenance of good engineering housekeeping practices. The aim of this paper is to set out in some detail those steps which might be taken when a hospital outbreak occurs and a water system identified as the source by epidemiological and microbiological studies. These proposed control measures were drawn up in consultation with microbiologists and epidemiologists and are based largely on personal experience gathered in the control of the outbreak of Legionnaires’ disease in Kingston District General Hospital in 1980 (Fischer-Hoch et aE., 1981; Fischer-Hoch, Smith & Colbourne, 1982) and several outbreaks in hotels both in the UK and overseas.