A RARE strain of legionella found in soil which left four Lothian gardeners in intensive care could be more common than first feared, a study has found.
Traces of legionella bacteria were found in 14 of 22 different brands of compost used by researchers at the University of Strathclyde in the first major study carried out in the UK into the bug and compost.
And in four of the cases, the potentially deadly legionella longbeachae strain – which left four fighting for their lives in the Capital’s Royal Infirmary and also hospitalised two people from the Tayside region in recent weeks – were discovered.
The results suggest that the bacteria, which until recently was unheard of in Britain and was more common in hot countries such as New Zealand and Australia, could result in far more people becoming ill after handling compost in future as it gains a foothold in Scotland.
Health Protection Scotland (HPS) had initially said it was believed the cases in Lothian were likely to be linked, but provisional findings of their investigation suggested there was no single source or supplier associated with the outbreak.
Dr Tara Beattie, of the University of Strathclyde’s Department of Civil and Environmental Engineering, led the study which uncovered the high levels of legionella in compost.
She said that there may be a case for adding warning labels to bags of compost to warn users of infection risks and inform them of precautions they should take to avoid infection – a practice that has already been adopted in parts of the southern hemisphere.
She said: “From a general hygiene point of view, if anyone is dealing with compost they should be making sure it does not get into their mouths and washing their hands. It’s important people know it’s a risk and follow the advice given.”
Dr Beattie said more research was needed into how humans became infected and the reasons behind the recent rise in cases. Theories include that the increase may be explained as less peat, which is not as hospitable to legionella as bark and sawdust, is now used in compost or that advancements in testing mean cases are being picked up when they would previously have slipped through the net.
While four of the 14 compost samples that tested positive for legionella contained the dangerous longbeachae strain, not all species found were dangerous to humans. The gardeners who were hospitalised are recovering.
Dr Beattie added: “A larger scale survey, covering a wider range of compost products is required to determine if these organisms, some disease causing, some not, are as widespread in composts as this initial study would suggest.”
Play it cool
GARDENERS have been advised not to give up their hobby, but to take precautions.
Health Protection Scotland moved to reissue advice yesterday, after publication of the University of Strathclyde study.
Compost should be stored in a cool place while gardeners should wear gloves and a mask if it is dusty.