Legionella in spa pools
In recent weeks there have been some high profile cases of legionella being found in a Co Donegal hotel spa, a number of unreported cases have been found in leisure centre spas. In March 2003 in a hotel in Cricket St Thomas two deaths where caused by Legionella. Over the past few years, in the UK there have been at least six reported deaths from pneumonia caused by Legionella infection and the source of infection was suspected as being a spa pool. The case brought against of Gillian Beckenham and Barrow Council by the HSE for manslaughter and health and safety offences also highlight the case for planned maintenance in air conditioning systems. Almost invariably poor maintenance and poor operation will have been a factor in the events leading up to the spa becoming infected. Generally poor design or installation is made worse by poor operation. It is estimated world wide that nearly 400 people have died after using a poorly managed spa. Legionella has two main forms. The most common form causes a short feverish illness and the other less common variant causes a more serious illness that leads to pneumonia and death in around 5-15% of cases.
Legionella is a naturally occurring gram negative bacteria. Without going into too much technical detail, this means that nearly all water supplies have a certain amount of Legionella at source. Legionella thrives on a diet of scale, sediment, scum, biofilms and protozoa, all of which are in ready supply in a busy spa. The nature of Legionella means that as bubbles are formed in the spa then the bacterium will attach to the external surface of the bubble and be spread into the atmosphere as an aerosol when the bubble bursts on the surface. Left unchecked and with an adequate nutrient supply, Legionella multiplies rapidly at a temperature above 20oC and below 40oC.
The operation of a spa will always reduce the volume of water and the bathers will introduce an ample supply of nutrients for the bacteria to thrive on; the spa amplifies and concentrates the volume of Legionella in the water.