From Dr John Gallagher, EHA:
A source of infection is rarely identified for sporadic cases of Legionnaires’ disease. Researchers at the UK Health Protection Agency found that professional drivers are five times more commonly represented among community acquired sporadic cases in England and Wales than expected. The researchers therefore investigated possible risks related to driving or spending time in a motor vehicle.
A case control study including all surviving community acquired sporadic cases in England and Wales with onset between 12 July 2008 and 9 March 2009 was carried out. Cases were contacted by phone and controls were consecutively recruited. The questionnaire included questions on driving habits, potential sources in vehicles and known risk factors. 75 cases and 67 controls were included in the study.
Multivariable analysis identified two risk factors linked to vehicle use associated with an increased risk of Legionnaires’ disease: driving through industrial areas and driving or being a passenger in a vehicle with windscreen wiper fluid not containing added screenwash. 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. The researchers estimated that around 20% of community acquired sporadic cases could be attributed to this exposure. A simple recommendation to use screenwash may mitigate transmission of Legionella bacteria to drivers and passengers .