Health professionals hope cases of Legionnaires' disease in Scotland's capital will peak this weekend, according to the chief medical officer.
The disease, thought to have been released into the community in the third weekend in May, takes around 10 days to incubate in the body.
Chief medical officer Sir Harry Burns said the peak depends on whether cooling towers in west Edinburgh that have been treated for infection are in fact the source of the outbreak. If not, cases may continue to rise.
Sir Harry 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 of 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."
Chairman of the incident management team, Dr Duncan McCormick, of NHS Lothian, has said further deaths cannot be ruled out.
One man has died, named locally as 56-year-old Robert Air, from Seafield in Edinburgh, while 12 people remain in intensive care.
Dr McCormick said: "We're hoping to see no further deaths. We're doing everything we can in terms of early diagnosis, appropriate treatment and intensive care, but I think we can't rule out any further deaths at this stage."
Two people are being treated outside the NHS Lothian area, in the Highlands and in the North of England, although they had visited the affected area.