A man aged 89 has died of legionnaires' disease and at least 19 people have been infected in an outbreak that has led to part of Barrow-in-Furness, Cumbria, being sealed off.
Nine of those diagnosed were in intensive care last night and 10 were described as poorly. A further 36 were suspected of having contracted the illness.
A search was under way to find the source and doctors warned that more people could be at risk. The outbreak of the disease, which kills up to 20 per cent of its victims, is one of the biggest recorded.
Some of the centre of the former shipbuilding town was closed to the public last night. A council-run leisure facility opposite the town hall was cordoned off by police, and water samples taken. Air conditioning units, in which the legionnaires' bacterium breeds, were shut down in eight buildings.
Asked if the disease was likely to claim more lives, Ian Cumming, the chief executive of the Morecambe Bay NHS Hospitals Trust, said: "Unfortunately, that is probably going to be the case."
The potential threat will only be known when the source is found. Hospitals a common source of the bacteria have been ruled out, so the signs point to the town centre, where all 20 people confirmed with the disease had been recently.
The bacteria thrive in water, and inhalation from droplets in air conditioning units is a common cause of infection. "It is likely to be a big air conditioning unit. It is not going to be one hanging on the wall in a shop," Mr Cumming said.Symptoms are flu-like, followed by fever and chills, and then a dry cough.
Non-urgent surgery was cancelled at the Furness General hospital and hospitals in Kendal and Lancaster were preparing to help treat cases. Mr Cumming said: "The disease has an incubation period of five to 10 days. We are looking at something in the region of another 10 people a day for the next 10 days."
The infected patients had been arriving at hospital with a diagnosis of pneumonia but medical staff became suspicious when the number rose significantly above normal levels.