Q&A: Edinburgh Legionnaires' disease outbreak

One man has died in an outbreak of Legionnaires' disease in Edinburgh. NHS Lothian said it was also dealing with 17 confirmed cases and another 15 suspected cases of the disease.

What is Legionnaires' disease?

It is a potentially fatal lung infection that is caused by the legionella bacteria. The disease, which is not contagious and cannot be spread directly from person to person, is caught by breathing in small droplets of contaminated water.

The condition is called Legionnaires' disease because it was first identified following an outbreak at a hotel hosting a convention of a veteran organisation known as the American Legion.

What are the causes?

Legionella bacteria is commonly found in sources of water, such as rivers and lakes, which sometimes find their way into artificial water supply systems, like air conditioning systems and cooling towers.

NHS advice is that large buildings, such as hotels, hospitals, museums and office blocks, are more vulnerable to legionella contamination because they have larger, more complex water supply systems and the bacteria can quickly spread.

What are the symptoms of the disease?

Initial symptoms include a high fever and muscle pain.

Once the bacteria begin to infect your lungs, sufferers may also develop a persistent cough.

Other symptoms include shortness of breath, chest pains and sometimes vomiting and diarrhoea.

What factors are linking the Edinburgh cases?

The majority of the confirmed cases are linked geographically to the Dalry, Gorgie and Saughton areas of Edinburgh.

NHS Lothians said investigations into the other cases and possible links with the area were continuing, but estimated the potential infection area was about 44 square miles, in an area that is relatively densely populated.

Sixteen water cooling towers in the south west of Edinburgh have been been treated with a range of chemicals to kill any bacteria.

The towers were identified as a potential source of the outbreak following the first reported cases on Sunday and were chemically treated on Sunday night and Monday morning.

Health Protection Scotland said the situation in Edinburgh is typical of the pattern for outdoor outbreaks of Legionnaires', which is why they think the cooling towers are source of the outbreak.

In the Edinburgh outbreak, the weather will also have affected how widely it has travelled.

Who is most at risk of contracting the disease?

Legionnaires' disease is three times more common in men than women, and mostly affects people aged over 50.

Everyone is potentially vulnerable to the disease but those who may experience a more severe form of infection include the elderly, smokers, diabetes sufferers, those with kidney disease and cancer patients.

An estimated 10% of people who contract Legionnaires' disease will die from complications arising from infection.

How is the disease treated?

It is treated by intravenous antibiotics. The information so far suggests the Edinburgh outbreak involves the most common strain of Legionnaires' disease, which is the easiest to detect and treat.

Health experts say the key to recovering from Legionnaires' disease is to get treated with the right antibiotic as soon as possible.

What happens next?

The next few days of the outbreak will be key to determining its scale.

Legionnaires' disease incubation period of is between two and 14 days but the average is five or six days, so the disease may peak in the coming days.

The Scottish government will hold a meeting of its Resilience Committee to co-ordinate plans to deal with the outbreak.