A further four cases of E.coli linked to burgers eaten at a concert venue have been identified, taking the total number affected in the outbreak to 15.
Investigators have linked the cases to the SSE Hydro in Glasgow, a major entertainment venue which opened in September.
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All but one of those affected by E.coli O157 live in Scotland, with one living in Cumbria. All are said to be recovering at home.
Last week, NHS Greater Glasgow and Clyde (NHSGGC) said seven cases had been identified, with four more confirmed on Monday and a further four today.
Investigators are looking particularly at the three days between January 17 and 19 at the Hydro, but advised anyone who visited the venue between January 17 and 25 and has experienced symptoms including stomach cramps, diarrhoea, nausea and fever to contact their GP.
The shows at the complex during the period were Top Gear, Del Amitri and Celtic Connections.
Two of the cases are from the greater Glasgow area, three are from Lanarkshire, five from the Lothian area, two from the Highlands, two from the Forth Valley and one from Cumbria.
Dr Eleanor Anderson, consultant in public health medicine at NHSGGC, said: "We are pleased that all the cases are recovering at home.
"Investigations are ongoing and while there is no conclusive evidence, our investigations have indicated that there may be a link to the consumption of burgers at the SSE Hydro.
"Glasgow City Council environmental health officers are working closely with the vendors to ensure all appropriate food hygiene standards are being met."
The 12,000-seat Hydro will host gymnastics and netball in the Commonwealth Games in July.
Operators said they have been contacted by environmental health officials and are awaiting further details.
A statement said: ''The initial review of our caterers' standard procedures have been found to be satisfactory and environmental health officers have seen nothing in their processes and practices which concerns them.
''We wish to assure the public that at this time we have no significant concerns in relation to catering for our patrons.''