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Legionella is back

Posted 14/06/2012 by sevans

Water is a life saver – in most cases – however, it is also well known as a potential carrier of a whole range of diseases. Although this role as a carrier is more often associated with the under-developed world, the developed world is not immune from its unfortunate side-effects as recent history shows.

As an example, recent headlines in the UK have tracked the progress of yet another outbreak of Legionnaires’ Disease – the result of the inhalation of waterborne bacteria – this time in Edinburgh, Scotland. 

The disease was so named after the first recorded outbreak in July 1976, which involved the spread of pneumonia among attendees at a convention of the American Legion in Philadelphia, Pennsylvania, US. In 1977, the organism responsible was identified as a previously unknown strain of bacteria, and thereafter given its name, Legionalla.

Over 90% of cases are caused by one bacterial strain Legionella pneumophila, which thrives in temperatures between 25 and 45 °C. It is a particularly aggressive bacterium, and the result of infection is often fatal, with a fatality rate ranging from 5 to 30%, particularly if there are also underlying health issues and antibiotic treatment is delayed. Significantly, as with other forms of pneumonia, most infections occur in older people, however, some people can be infected with the Legionella bacteria and have only mild symptoms or no illness at all.

This latest UK outbreak has now claimed two lives, with over 80 confirmed and suspected cases, and the source originally traced to somewhere in the south west sector of the city. This area was then narrowed to commercial operations with cooling towers, which were all investigated. The companies included a pharmaceutical firm, a food company, a whisky distillery and an insurance business, which although initially might be considered a strange candidate, actually has a number of cooling towers for its IT server array. A total of 16 cooling towers were examined microbiologically and treated to kill any bacteria.

Most recently, sometime after the outbreak was first diagnosed, the distillery has been identified as the source, with the company being issued with an improvement notice by the UK Health & Safety Executive for alleged failures to adequately control the risk of legionella in one of its cooling towers. All of the company’s cooling towers have been shut down and production halted at the site.

Although water containing the bacteria can be drunk without infection, the disease is transferrable through any breathable spray, whether it be from a shower head or commonly the output from cooling towers, which provide ideal temperature conditions for proliferation of the bacteria. And it can be particularly difficult to trace the source as the recent outbreak in Edinburgh has demonstrated.

Most of us in the developed world take water treatment for granted and it can therefore slip in the list of priorities for preventative maintenance, especially in constrained economic times. The solutions are readily available from the chemical industry but it is essential that microbiological testing and treatment are seen as an essential part of facility operations.

Any cost savings can evaporate in the event of such an outbreak, with reputations lost in an instant, apart from the cost of any loss of life and illness.

Neil Eisberg - Editor

Add your comment




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    15/10/2013 06:33

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    14/10/2013 07:07

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  • Anonymous said:
    13/10/2013 11:09

    Well Scotty, you really were not clear as to what you were tnkilag about since there actually is no Florida Department of Motor Vehicles, there is a Florida Department of Highway Safety and Motor Vehicles. Since you live in Pasco County I thought you were tnkilag about the Pasco County Tax Collectors Office which handles all the face-to-face duties of the license process of the Florida Department of Highway Safety and Motor Vehicles in the county. As for keeping up, my friend, more than two thirds of Florida's county tax collectors already offer some of driver's license services. But by 2015, the plan for most areas is for the tax collector, or online, to be your only options as mandated by state law. Now that we have cleared up this confusion tell me specifically what problems you have had with the employees of the Florida Department of Highway Safety and Motor Vehicles that causes you to summarily attack them all .

  • Anonymous said:
    21/06/2013 10:19

    It's worth noting that Legionella tetinsg of cooling towers is required in the UK, and responses to trigger limits are also required by law. Penalties can be severe, but assigning responsibility when the distances over which Legionella can be dispersed via aerosol are large is of course a difficult task. While cooling towers are often assumed to be the source of Legionella outbreaks culturable legionella have also been isolated from hospital showers and potable water systems, as well as roadside puddles after a rainstorm. Unlike most other developed nations the United States does not mandate Legionella tetinsg, and in fact voluntary guidelines are just being issued by industry groups and the CDC.

  • Anonymous said:
    15/07/2012 06:27

    Legionella has been shown to be a common isaolte from potable water distribution systems, including hospital shower heads and water taps in patient rooms, particularly in rooms which have been unoccupied recently. In addition, Legionella have been isaolted in a European study from roadside puddles after a rainstorm. They are likely more widely distributed then first thought. Both the EU and Australia mandate regular testing of cooling towers for Legionella, and specify trigger limits for a disinfection response. No such mandate exists in the USA, although the CDC, ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers), and the CTI (Cooling Tower Institut e)do have suggested guidelines.

  • Anonymous said:
    13/07/2012 05:53

    Jon: you are correct in that the ASHRAE satdnards do not mandate testing; neither does the CTI or CDC documents because a mandate can only come from legislative/lawmaking bodies. Testing is suggested, though, otherwise how to know if you have a problem? Viable testing at contract labs (for example, Biosan) has a turnarond time of less then three weeks, and there are both PCR and antibody-based tests available for rapid determination for the presence of pathogenic (serotype 1) Legionella, although, as you point out, they are not indicative of viable pathogens. However, if you have a presumptive positive (rapid) test and a heavily-fouled tower with abundant biofilm, a reasonable person should be thinking about treating that tower as if it had Legionella.