Bacteria That Can Cause Disease In Humans

Five gardeners have been infected by Legionnaires’ disease linked to bags of compost.

The cases – all recorded since August – have led to warnings about handling shop-bought compost.

Scientists from the University of Strathclyde carried out tests on 22 commercial brands and found evidence of the bug in 14 of them.

Four showed positive for a fatal strain – Legionella longbeachae.

Tara Beattie, the lead researcher, said a move away from traditional peat could be responsible.

‘Disease causing micro-organisms are widespread in the environment, and therefore it is not too surprising that species of Legionella that can cause human disease are present in compost,’ she said.

‘Any environment where you have pathogenic bacteria could be a source of infection, and we already know that compost has been linked to human Legionella infection in Australia and New Zealand.

‘Within the UK and across Europe, composts have traditionally been composed of peat, whereas sawdust and bark are more often used to produce compost in Australia and New Zealand where Legionellosis associated with compost is more common.

‘It may be that the change in composition of composts in the UK, moving away from peat-based products, could be resulting in species such as Legionella longbeachae being present in compost and therefore more cases of infection could occur.’

She suggested manufacturers might want to place hygiene warnings on compost packaging.

Over the past five years, at least one gardener has died from a Legionnaires’ infection.

Last month, health experts recommended putting warning labels on compost bags after a spate of Legonella longbeachae infections in Scotland.

 

What is legionella longbeachae?

Legionella longbeachae can be found in potting mixes, compost heaps and composted animal manures.

How Legionella longbeachae are spread is uncertain.

The bacteria may be breathed in or spread from hand to mouth.

Legionella longbeachae can remain on hands contaminated by handling potting mix for periods of up to one hour and can be removed by washing.

It cannot be spread person-to-person

To minimise the risk of infection when handling potting mix, gardeners should:

Wear a face mask

Open bags with care to avoid inhalation of airborne potting mix

Moisten the contents to avoid creating dust

Always wear gloves to avoid transferring the potting mix from hand to mouth

Always wash hands after handling potting mix - even if gloves had been worn

Five people have been affected since the outbreak began in August - with the latest victim being treated in hospital in Dundee two weeks ago.

Dr Beattie said: ‘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.

‘It should be emphasised though, that although Legionella seem to be common in compost, human infection is very rare, especially if you consider the volume of compost sold and used.

‘But with any potential source of infection precautions should always be taken.

­—Dailymail London