But environmental health officials have now extended the search to the outskirts of the city after failing to find the source of the outbreak.

The search is likely to continue for the next few days, but the Health Protection Agency (HPA) said it was possible it would never be found.  A man and woman in their 70s have died.

There is nothing to say we are not going to get any more cases over the next few days

Dr Mike Deakin, Hereford's director of public health

Two middle-aged people are still in intensive care at Hereford County Hospital while two new cases have been confirmed on Saturday.

John Rendle's cousin is one of the victims who is on a ventilator after she was admitted to the hospital a week ago.

He visited her there on Saturday.  "There is shock, but there's also amazement. She doesn't go out anywhere except maybe by taxi to a supermarket because she's very disabled," he said.  GPs across the region have been alerted to the symptoms of the disease - which include a flu-like illness with muscle aches, tiredness, headache, dry cough and fever.

Anyone with the symptoms is advised to contact their GP. Samples have been taken from the confirmed cases to see whether patients had caught the disease from the same source. Results are expected early next week.  Dr Mike Deakin, Herefordshire's director of public health added further cases of the disease linked to the outbreak could not be ruled out.  He said the county would expect to see an average of one case every two years.

"That is why we are particularly concerned by this," he said.  "There is nothing to say we are not going to get any more cases over the next few days.

Contaminated particles

"The incubation period is normally between two and 10 days but can be up to three weeks."

Legionella pneumophilia, which causes the disease, is widely distributed in the environment and found in hot and cold water, and air conditioning systems in very small numbers.  But when it comes into contact with warm water it multiplies quickly and can spread through the air in very small droplets.  Inhaling contaminated airborne particles is the main route of transmission for the disease.  Death occurs in up to 15% of previously healthy people who contract the disease.

For more information contact:

Alan L. Wozniak, CIAQP

(800) 422-7873 ext. 802

info@pureaircontrols.com