There are now 74 confirmed and suspected cases of Legionnaires' disease amid an outbreak in the Scottish capital.
It also emerged that the Health and Safety Executive (HSE) has served an improvement notice on an Edinburgh company for alleged failures to adequately control the risk of Legionella in a cooling tower.
The notice was served on the North British Distillery Company and refers to a tower in Wheatfield Road in Edinburgh.
An HSE statement said the firm has already taken all three of its cooling towers at the site out of operation. Issuing the improvement notice does not mean the tower concerned is where the outbreak originated.
The search for the source of the disease outbreak has centred on cooling towers at four sites in the south-west of the city, which have been "shock-treated" with chemicals.
Scottish Health Secretary Nicola Sturgeon has said it is "not always possible to conclusively determine the precise source of an outbreak".
She said the increase of 13 in the total number of confirmed and suspected cases had been expected.
Twenty-eight people have now been confirmed as having Legionnaires' disease and another 46 are suspected of having it.
So far one man has died, named locally as 56-year-old Robert Air, from Seafield in Edinburgh.
Fourteen people are in intensive care, a further 30 are in general hospital wards, 15 are being treated in the community and 10 have already been discharged from hospital.
Ms Sturgeon said: "As we expected, we have seen a rise in the number of cases associated with this outbreak today. It is reassuring to see that 10 people have now been discharged from hospital."
Those confirmed as having the disease range in age from 33 to 76, with more men than women infected.
Four patients are now being cared for outside the NHS Lothian area: one in Glasgow, one in the north of England, one in the NHS Tayside area and one in NHS Lanarkshire. All these cases are considered to be linked to the outbreak in the south-west of Edinburgh.
Ms Sturgeon said: "NHS Lothian continues to be very busy and contact has been made with other health boards in case capacity at other hospitals is required.
"The risk to the general public remains low but anyone with concerns should contact their GP or NHS 24's dedicated hotline on 08000 858 531."
By 10pm last night the hotline received 492 calls.
Ms Sturgeon said: "Investigations into the source of this outbreak are continuing.
"It is important to note that in issuing an improvement notice, the HSE does not believe there is an immediate risk to workers or members of the public. Nor can it be assumed that this tower is the source of the outbreak. Investigations into all of the other towers in the area are continuing."
Dr Duncan McCormick, who chairs the incident management team and is a consultant in public health medicine at NHS Lothian, also said the increase in confirmed and suspected cases was "exactly in line with what we expected and what we have predicted so far".
He said "We expect that the numbers of patients affected will peak over the weekend and then begin to fall as we move into the beginning of next week.
"The majority of patients who are presenting now are also on the lower end of the sickness scale and are therefore more likely to be treated in the community with appropriate care than be admitted into hospital, meaning that they are also unlikely to have underlying health conditions."
A statement from the HSE said it served the improvement notice on North British Distillery because of a "failure to deliver and implement a sustained and effective biocide control programme in one cooling tower".
It must now satisfy the HSE that it has appropriate controls in place by June 29. The notice can be appealed by the company within 21 days.
Safety inspectors visited the firm as part of the investigation into the outbreak, with visits to other companies also taking place.
Scotland's top doctor Sir Harry Burns said that when the outbreak peaks depends on whether the cooling towers treated for infection are in fact the source of the disease. If not, the number of cases may continue to rise.
The Chief Medical Officer told BBC Radio Scotland's Good Morning Scotland programme: "Typically, it takes about six to 10 days for the disease to incubate. So, they were treated last weekend and we would hope in the course of the next few days we would begin to see a drop-off in the number of cases.
"If that is observed then we can be more confident that these cooling towers are the source.
"If it doesn't, then clearly there is a more complicated background to this and further investigations will be required.
"Looking at the timescale that people were beginning to present, it looks as if the third weekend in May may well have been the time when this infection may have got out into the community.
"Therefore, 10 days later is around about this weekend, so we will be keeping an eye on the number of cases as they evolve over the next few days."
A spokesman for North British Distillery said: "Our thoughts are clearly with the families of those affected by this situation.
"Ensuring the health and safety of our employees and the local community is our highest priority.
"On Thursday 7 June we voluntarily took our cooling towers off-line until the legionella results from samples taken earlier this week are reported.
"While this precautionary operation is under way we have temporarily ceased distillation.
"Industrial cooling towers remain only one potential source of the infection and North British Distillery is one of a number of sites with such towers in Edinburgh.
"We continue to work closely with the HSE and all other relevant authorities in relation to this issue.
"North British Distillery would like to reaffirm that the Improvement Notice issued by the HSE today does not mean that this cooling tower has been identified as the source of the outbreak."