Screenwash and Legionnaires' disease
The BBC, and other media sources, report that operating a windscreen washer without added screenwash increases the risk of catching Legionnaires’ disease. The source is a well-conducted study led by the Health Protection Agency in the South West and published in the European Journal of Epidemiology.
The results are plausible: using windscreen washers without screenwash increases the risk of catching Legionnaires’ by almost 50-fold, the study suggests, though the confidence intervals are wide (OR 47.2, 95 per cent CI 3.7 to 603.6). Using screenwash, which is assumed to kill the bacterium, could prevent a fifth of community-acquired sporadic cases, the authors estimate.
But this is a story that cries out for numbers. How many cases does this actually mean? HPA figures show 164 community-acquired cases in 2009, of which 22 were linked to outbreaks. So the number of community-acquired sporadic cases is 142, of which 28 (1/5) might have been prevented. Legionnaires’ is a nasty disease, so preventing 28 cases a year is certainly worthwhile.
But having the figure is vital to understanding the story properly. The BBC incorrectly implies that it applies to all cases in England and Wales in 2009 (345); so does The Guardian and The Daily Telegraph. Still, the HPA’s advice to add screen washer makes sense, even if those driving with windows open may still be exposed to spray from others who don't.
SadButMadLad (not verified) wrote,
Mon, 14/06/2010 - 20:24
But is worthwhile scaring everyone into thinking they are going to die if they don't put screenwash into their bottles? Because thats what these stories do. Also the more they publish such "scare" health stories and the more they are shown to be sham (and as people realise that they aren't dropping like flies when they don't change their habits) the more people will think the scientists are crying wolf.
More people die from car accidents than possibly from legionnaires via screenwashes. The emphasis should be on the outbreaks because that is where the peak numbers come from.
I'm just waiting for a manufacturer to say that their screenwash incorporates an anti-bactricide.
Recusant (not verified) wrote,
Thu, 17/06/2010 - 14:40
As has been pointed out by others, this all seems highly unlikely. The Legionnaire's bacterium requires still and oxygen exposed water to thrive. In addition it cannot tolerate anything other than mild and gradual fluctuations in temperature. Neither of these two conditions could be said to apply to the screen wash bottle of any vehicle.
Tim Jones (not verified) wrote,
Fri, 18/06/2010 - 09:26
SadButMadLad, sorry for the pedantry, but is anti-bactricide something to do with a campaign against killing camels? I assume you mean an anti-bacterial or a bacteriocide?
Legionnaires Disease (not verified) wrote,
Tue, 22/06/2010 - 14:28
Absolutely shocking, it is commonly known that institutions such as hospitals, prisons etc have always had higher incidences of legionella, but perhaps we all need to carry out our own personal Legionella risk assessment - not!
Legionnaires Disease (not verified) wrote,
Sat, 10/07/2010 - 13:43
how scary to think such a serious disease could lurk in your car!
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