Health Secretary Nicola Sturgeon told MSPs the number of people confirmed to have Legionnaires disease in Edinburgh had risen to 24, and a further 27 are suspected to have the infection.
The health secretary was delivering a ministerial statement on the outbreak on 7 June 2012.
Ms Sturgeon said : "I can advise parliament that as of last night the total number of confirmed cases stood at 24 with a further 27 in the suspected category.
"Presiding officer it remains the case at this stage that there is no identified link between these cases other than an association with the affected areas in the south west of Edinburgh.
"Of the total 51 cases, 14 are being treated in ITU (intensive care units), two have already been discharged from hospital and the remainder are being treated in general wards or in the community."
The source of the infection is still being investigated with the potential area for infection estimated at about 44 square miles.
Scottish Labour's health spokeswoman Jackie Baillie questioned the speed with which affected communities in Edinburgh were given information about what she called "the biggest outbreak in a generation".
Ms Sturgeon praised NHS Lothian and said the health board's response had been "absolutely superb".
She said all agencies had acted timeously.
The health secretary also told MSPs a dedicated NHS 24 advice line had been established to deal with queries about the outbreak on 08000 85 85 31.