The patient had recently been abroad and experts believe the victim contracted the infection while out of the country.

But it is not yet know what caused a further two cases – both in Fleetwood.

One of the Fleetwood victims is seriously ill in hospital. while the other is said to be making good progress towards recovery.

According to the Health Protection Agency, the cases of Legionnaires' disease on the Fylde coast are "sporadic".

The HPA is now investigating the two Fleetwood cases to establish if there was a common cause.

Dr Steven Gee, consultant in communicable disease control with the HPA's Cumbria and Lancashire Health Protection Unit, said: "We are looking into the cases with colleagues from NHS North Lancashire and Wyre Council's Environmental Health Department.

"People should remember sporadic cases of Legionnaires' disease are not uncommon and it may very well be that the cases are not linked.

"However, as they occurred at the same time in broadly the same geographical area, it is important we investigate.

"If we do find there is a source of infection in the locality, we will of course take immediate steps to eliminate the risk."

Detailed questionnaires are currently being filled in by the patients' families to see if there is any link between the cases.

Legionnaires' disease is caused by the legionella bacteria, common in standing environmental water.

Symptoms of the disease – which can cause serious illness and even death – are flu-like and include muscle aches, tiredness, headaches, dry cough and fever which can lead to pneumonia.

Diarrhoea, confusion and kidney failure can occur in addition to chest and breathing problems.

It is rare for anyone under the age of 50 to be affected by the illness.
The latest cases come just weeks after Karen Ann Taylor died in hospital after becoming ill with with the disease following a stay at Blackpool holiday camp Pontin's.

Mrs Taylor, 53, from Birmingham, was diagnosed with Legionnaires after returning from holiday in the resort in July.

She was later admitted to Selly Oak Hospital, where she spent several weeks before losing her fight for life.

The disease is most often contracted by inhaling mist from water sources such as whirlpool baths, showers and cooling towers which are contaminated with Legionella pnuemophila bacteria.