Vigilance must be eternal but balanced

EDITOR—Joseph underlines the paradox of larger outbreaks of legionnaires' disease when understanding of causality is greater than ever.1 She gives four explanations—loss of vigilance in maintenance of water systems, greater clinical awareness, better surveillance, and easier diagnosis. She calls for enhanced surveillance of both sporadic disease and outbreaks and for greater vigilance in control. Some lessons from studies of legionnaires' disease in Scotland are pertinent to concerns fuelled by outbreaks in England this summer.

In Glasgow a survey conducted after two outbreaks, including the largest in the United Kingdom up to 1984, showed up difficulties in maintaining an accurate register of cooling towers, poor understanding among some managers of premises about the nature and location of cooling towers and evaporative condensers, and breaches of guidelines, usually on structural issues—for example, control of the drift of cooling towers rather than non-use of chemicals.2 The problems would have been even greater without the publicity of the preceding outbreaks. Breaches of guidelines on the maintenance of hot water systems were also of concern and constituted a hazard for legionnaires' disease.3 …