GARDENERS are being warned to wash their hands after using compost following a series of Legionella cases, including one death in the past four years.

There have been six cases in Scotland since 2008, each affecting gardeners, according to Health Protection Scotland.

The risk of the infection, which can cause headaches, diarrhoea and pneumonia, to gardeners has led to other countries introducing warning labels on compost bags. The move is now being considered for Scotland.

Dr Martin Donaghy, HPS Medical Director, said three of the cases in Scotland were laboratory confirmed, two probable and one possible.

Mr Donaghy said: "All cases have been keen gardeners, a major proportion of whose time has been dedicated to this hobby.

"However no specific gardening activity, for example, or type or source of compost have been identified as common to all or almost all of the cases and therefore as being the likely source of the infection.

"The cases have occurred at different times of the year.

"Legionella longbeachae has a recognised association with compost. The strain is unusual in Scotland but is well known in Australia and New Zealand, where bags of compost carry warning labels.

"Evidence from Australia has highlighted the importance of hand-washing after handling compost.

"Given the volumes of compost used in the country, the overall risk to gardeners is very low. As is the general pattern with legionnaires' disease, cases to date have generally been in older people with underlying health issues and smokers."

The current advice to gardeners is to wash their hands well after carrying out gardening tasks, especially before smoking or eating.

Mr Donaghy said: "HPS is leading an investigation to ascertain whether anything more precautionary needs to be done."

The Growing Media Association has reportedly said that since 1990 there have been 12 reported cases of Legionella potentially connected to the longbeachae microbe in Great Britain, adding "in the same period, the UK public has used well over a billion bags of compost".

The strain was first found in Long Beach, California, is mainly confined to soil and potting compost and is sometimes known as Pontiac Fever.