New research from the UK suggests that as many as 1 in 5 of community-acquired sporadic cases of Legionnaires’ disease occur as a result of not adding screenwash, which normally contains anti-bacterial agents, to windscreen wiper fluid in cars and vans.
The study was the work of researchers at the UK’s Health Protection Agency (HPA), and you can read a paper about it in the 7 June online first issue of the European Journal of Epidemiology.
Legionnaires’ disease is a rare type of pneumonia caused by bacteria from the genus Legionella that live in water. In 2008, there were 359 cases reported in England and Wales, mostly in men, and 40 per cent were overseas travel-related. This study focused on Legionnaires’ disease acquired in the community, as people go about their daily lives, as opposed to cases where exposure most likely occured during foreign travel.
In their background information, co-author Dr Isabel Oliver, regional director of the HPA South West, and colleagues, wrote that it is not easy to find a source of infection of sporadic cases of Legionnaires’ disease, but they noticed that in England and Wales, professional drivers were five times more likely to have it than other people and decided to explore the possible risk of exposure for drivers and passengers.
They carried out a case control study that included all the surviving community acquired sporadic cases in England and Wales that started with symptoms between mid July 2008 and early March 2009.
They contacted the cases by phone and then from their details recruited consenting matching controls. All who consented to take part in the study filled in questionnaires about their driving habits, potential sources of infection in vehicles and other known risk factors.
When the researchers analysed the results, they had data on 75 cases and 67 controls. They found that:
- Two exposures linked vehicle use with an increased risk of Legionnaires’ disease.
- One was driving through industrialized areas (odds ratio OR 7.2, 95 per cent confidence interval CI ranged from 1.5 to 33.7).
- The other was travelling in a vehicle where no screenwash had been added to the windscreen wiper fluid (OR 47.2, 95 per cent CI 3.7 to 603.6).
The researchers concluded that:
“Not adding screenwash to windscreen wiper fluid is a previously unidentified risk factor and appears to be strongly associated with community acquired sporadic cases of Legionnaires’ disease.”
They suggested that around 1 in 5 of community acquired sporadic cases of Legionnaires’ disease could be attributed to this exposure, and a simple way to reduce the risk of transmission of Legionella bacteria in the community would be for people to make sure they add screenwash to the windscreen wiper fluid in their vehicles.