8 September 2010 Last updated at 11:52 ET

Legionnaires' probe focus on south Wales industry sites

The cases cover seven different council areas across south Wales.

Health officials are focusing on industrial premises in their search for the cause of a Legionnaires' disease outbreak in south Wales.

A 64-year-old woman has died and is among two possible cases still being investigated, say health officials.

A total of 12 cases are now linked to the outbreak and all have required hospital treatment.

Inquiries continue into the source of the illness, which is clustered around the Heads of the Valleys corridor.

The focus is on industrial premises and large air conditioning systems.

Public Health Wales (PHW) said the woman died in hospital on Monday.

Jonathan Richards, a GP in Merthyr Tydfil, said diagnosis was hard as the source of the outbreak was so far unknown

It has not yet been confirmed whether she died from Legionnaires' disease.

Meanwhile, information has been circulated to GPs advising what steps should be taken if patients have symptoms.

Public Health Wales, the Health and Safety Executive and seven council areas are involved in the investigation.

Dr Gwen Lowe, consultant in communicable disease control for PHW said: "Legionnaires' disease is a rare but potentially life threatening illness.

"Most of the cases of Legionnaires' disease that are notified to us are isolated cases, but outbreaks can occur.

"People become infected when they inhale Legionella bacteria which are spread through the air in the form of a fine mist or droplets from a contaminated water source.

"Legionnaires' disease cannot be passed from person to person."

A multi-agency outbreak control team has met to investigate the outbreak.

Consultant epidemiologist Dr Brendan Mason said: "The critical thing is to find source so it can be removed and then no-one else is put at risk.

"We need to look very carefully at the precise movements of the cases in that period before they became unwell and we then look for common links between them in an attempt to narrow down the search for a source.

"You are then looking at sources like cooling towers that under the right atmospheric conditions can disseminate this organism over very wide areas, many miles in fact."

He confirmed that health officials were now looking at cooling towers and industrial areas in the Heads of the Valleys corridor.

"It can be very difficult to tie down the source," he added.

"A number of outbreaks are investigated and the source is never found."

Map showing the areas, mostly in the valleys, where the investigation is concentrating

Hugh Pennington, emeritus professor of microbiology at the University of Aberdeen said Legionnaires' was "an infection that hits the elderly hardest".

He said: "There are various antibiotics that do work quite well. But in a minority of cases the antibiotics don't keep the bug at bay so early diagnosis is quite important."

Legionnaires' disease facts

• Legionnaires' disease is an uncommon form of pneumonia caused by the legionella bacterium.
• All ages can be affected but the disease mainly affects people over 50 years of age, and generally men more than women.
• People become infected when they inhale legionella bacteria which have been released into the air in aerosolised form from a contaminated source.
• Once in the lungs the bacteria multiply and cause either pneumonia or a less serious 'flu-like illness.
• Anyone worried about their health should contact their GP.
• Source: Public Health Wales

Legionnaires' disease begins with flu-like symptoms and can lead to pneumonia, usually in adults.

Anyone worried about their health should contact their GP.

The councils involved in the investigation include Cardiff, Merthyr Tydfil, Rhondda Cynon Taf, Caerphilly, Blaenau Gwent, Torfaen and Monmouthshire.

The outbreak control team, which also includes representatives from Cwm Taf Health Board, Aneurin Bevan Health Board, and Cardiff and Vale University Health Board, will continue to monitor the situation closely.