Race to pinpoint Legionnaires' outbreak in Scotland

Industrial cooling towers are suspected of being the cause

Sixteen companies including a pharmaceutical company, a distiller and a food producer have had their cooling towers treated in an attempt to end the outbreak of Legionnaires’ disease in the Edinburgh region of Scotland.

One of the cooling towers in the Dalry, Gorgie and Saughton areas in the south west of the Scottish capital is suspected of spreading the Legionella bacteria. As a precaution all the towers have been subjected to “chemical shock” treatment using chlorine. The outcome of investigations into which tower is the likely cause is not expected until the weekend.

So far one person has died and at least another 21 people have been confirmed as having the disease, with more cases waiting to be identified. Some accounts put the current numbers of hospitalised suspect cases as high as 40.

The virulence of Legionella bacteria puts older people and those with prior medical issues, such as lung or heart problems, at high risk from the disease.

Testing of cooling towers for Legionella bacteria is already a legal requirement. Should any of the companies be implicated in the outbreak further investigations will be inevitable as to whether the required procedures were neglected, or whether current requirements are adequate to prevent such outbreaks.

A study1 carried out as a result of an outbreak of Legionnaires' disease in Hereford, UK 2003, illustrated the importance of cooling towers as a source of Legionnaires' disease and the importance obtaining both clinical and environmental samples.

The emissions from the 16 cooling towers cover a wide area that is heavily populated, also raising questions about the current cleaning regimes for such towers in populated areas.

1. Kirrage D, et al ; Hereford Legionnaires Outbreak Control Team. Respir Med. 2007 Aug;101(8):1639-44.