RHS set to unearth the nations gardening knowledge with its first ever Dig Together Day (1,5 & 6 September)
Legionnaires' disease in Compost
Now before you all go off and throw your compost bags away there seems to be a few inconsistances with the way this story has been reported in the press.
Firstly when the case in Scotland was reported in 2008, the unfortunate victim Mr Drew Murphy, who I hope has made a full recovery, was said to have contracted the disease by breathing in compost dust which contained Legionella longbeachae. This week the press is saying it was caused by breathing in water droplets containing the disease. Being the type of person who hates these inconsitancies in the press I decded to investigate the claims of these 'Experts'.
Legionnaires disease was first recorded in Philadelphia in 1976 when large numbers of the American Legion, an association of military veterans, caught the disease in an hotel they where staying in. In this case and many other cases identified over the next twenty years or so the cause was contaminated water in the hotels air conditioning system. The veterans caught the disease by breating in water droplets in the air. However there are many forms of Legionnaires' disease, well about 50 actually, and the one which affected Mr Murphy in Scotland was frst identified in Australia and New Zealand in 1989/1990 where tests where performed on bags of compost and potting mix and 73% of them where found to contain the disease. Thats quite a high amount I thought, and considering them number of people who use compost it seems to be a very very small chance of anyone catching the disease.
Now the 'Experts' quoted by the press this week are in actual fact the European Centre for Disease Control and Prevention, Stockholm, Sweden, and they say that it is hard to prove the disease is contained in commercial potting compost soil as the cases are rare and often appear in single cases. The article they produced also quotes the Auckland Public Health Service's advice on how to safely work with compost, and it is this part of the article which is mis-reported as being 'advice from the experts'.
After reading various articles and research documents dating back to 1990 it seems the general advice on how to avoid the disease is to dampen down the compost before you use it, as it's the dust particles being breathed in which can cause the disease. If you want to be more cautious wear a face mask when handling the compost. A very simple solution to a very, very rare problem.