Most outdoor outbreaks of Legionnaires' are linked to cooling towers, and Ms Sturgeon said action was taken on the Sunday night and Monday to treat these.

Cooling towers at four sites in the area were "shock dosed" with chemicals to treat bacterial growth, Ms Sturgeon said.

But she added that she had been told last night that some of the towers may need further treatment.

The Health Secretary said discussions were taking place between the City of Edinburgh Council and the Health and Safety Executive to determine what, if any, further treatment is considered appropriate.

She also said that over the last two days a further three towers in two different sites had also been tested and treated.

Ms Sturgeon said confirming the source of the outbreak was a "central priority" but it was "an extremely complicated process".

Testing and analysis was taking place, with Ms Sturgeon telling MSPs: "We hope that they will begin to provide more specific answers about the source of the infection over the next few days.

"It is not always possible to conclusively determine the precise source of an outbreak."

In such cases, conclusions had to be reached about the source on the basis of the balance of probabilities.

"Every effort is being made to investigate the potential source of this outbreak.

Second death.

This is a guy is a friend of mine

And he did not have 'underlying health problems'

I know the whole thing is probably of no interest to anyone not living here but the thing that pisses me right off is they know the source, but because of the deal to invest in the Scottish economy they never be named pubilcally .

2 needless deaths and many more still seriously ill in hospital just because some brewery cut corners with it's cleanliness .

They should be named and shamed and fined and be made to give a public apology

Second death.

This is a guy is a friend of mine

And he did not have 'underlying health problems'

I know the whole thing is problem of no interest to anyone not living here but the thing that pisses me right off is they know the source, but because of the deal to invest in the Scottish economy they never be named pubilcally .

2 needless deaths and many more still seriously ill in hospital just because some brewery cut corners with it's cleanliness .

They should be named and shamed and fined and be made to give a public apology