The latest figures show 41 confirmed cases and 48 suspected. Those with confirmation of the disease are all aged between 33 and 81, with more men than women affected.

Two men both with underlying health conditions have died from the outbreak.

The first case was identified on the 28th of May but the source of the infection is still being investigated by the Health and Safety Executive (HSE) and Edinburgh City Council. NHS Lothian believes the potential area of infection is about seven-and-a-half miles in diameter and that means the estimated area for infection is approximately 44 square miles.

The hunt for the source of the outbreak has so far centred around a whiskey distillery in the south west of Edinburgh. The HSE has served an improvement notice on the North British Distillery for alleged failures to adequately control the risk of legionella. Cooling towers at the distillery have been shut down as a preventative measure although there is no conclusive proof the towers are the source of the disease.

The HSE are investigating other possible causes and have warned the source of the outbreak may never be ‘conclusively identified’.

Legionnaires’ disease

Legionnaires’ disease is a potentially fatal form of pneumonia caught by breathing in small droplets of contaminated water. The disease is not contagious and cannot be passed from person to person.

The disease is three-times more common in men than women, and the over 50’s are most at risk. The elderly or those with underlying health conditions, smokers and heavy drinkers are also more prone to developing the disease.

Symptoms of the disease can range from a mild headache and nausea to a high fever, muscle pain and chills. If the bacterium infects the lungs sufferers may also develop a persistent cough, shortness of breath and chest pain.

Legionnaires' disease is most commonly contracted from air conditioning systems, hot and cold water systems, cooling towers and whirlpool spas.

Peter Mulhern, a serious injuries solicitor at Thompsons said: “Outbreaks of Legionnaires' disease are uncommon, but when they do strike the disease can affect large numbers of people. Health officials will be wanting to pinpoint the source and to prevent a further spread of the disease as soon as possible.

“The owner of the premises where the bacteria came from could face a charge of corporate manslaughter or, in Scotland, corporate homicide if there has been a gross failure in the way the water treatment systems were managed and the failure was the cause for the build up and escape of the legionella bacteria.”