Å®ÉúСÊÓƵ

Warning labels will appear on potting compost sold in Australia following
the deaths of two Queensland men from Legionnaire’s disease. A legionella
bacterium has been found in potting mix used by the two men.

Last week Queensland’s health minister, Ken Hayward, urged gardeners
not to panic. ‘In scientific and statistical terms, the risk of contracting
legionella pneumonia from potting mix could only be described as infinitesimal,’
he said. A scientific panel now has a month to draw up a national policy
on the labelling of potting soils and mixes.

The industry is well aware of the problem. In Queensland, 100 volunteers
from nurseries are being examined for antibodies to legionella. Preliminary
results from the study show that ‘potentially infective legionella species
were commonly found in decaying plant material’.

‘We are starting to believe that it is unfair to blame just potting
mix,’ says Gerry Murphy, the Queensland Director of Public Health. ‘There
are many potential sources in the garden.’

The organism responsible for the deaths in Oueensland is Legionella
longbeachae, a strain first identified in Long Beach, California, in 1980.
It has also been isolated in Sweden from a patient who repaired greenhouses.
Research in Australia has linked the organism to soils and potting mix.

Last week, at a conference on legionella in Florida, Trevor Steele from
the institute of Medical and Veterinary Science in Adelaide, presented research
from South Australia, where more cases of legionella have been reported
than in any other state. Steele has isolated L. longbeachae and other strains
of legionella in 73 per cent of 45 potting soils made in Australia by 13
manufacturers. He did not find the bacteria in 19 potting soils made in
Greece, Switzerland and Britain, where peat, rather than composted sawdust
and bark, is the major ingredient.

One suggestion for making the soil safe is to sterilise it. But Scott
Cameron, of the South Australian Health Commission, says this reduces the
number of bacteria only temporarily ‘They grow again even more virulently
after treatment stops. It’s not the full answer.