A further six cases of E.coli linked to burgers eaten at a concert venue have been identified, taking the total number affected in the outbreak to 21.
Investigators have linked the cases to the SSE Hydro in Glasgow, a major entertainment venue which opened last September.
All but one of those affected by E.coli O157 live in Scotland, with one living in Cumbria. All patients are either fully recovered or are recovering at home, NHS Greater Glasgow and Clyde (NHSGGC) said.
Investigators identified three days between January 17 and 19 as the likely infection period. The Hydro hosted performances by Top Gear, Del Amitri and Celtic Connections during that time.
The health board said it is unlikely that more people will develop symptoms as the incubation period has now passed, but appealed for anyone who was at the venue between January 17 and 19 and has experienced symptoms including stomach cramps, diarrhoea, nausea and fever to contact their GP so that all cases can be recorded.
Dr Eleanor Anderson, consultant in public health medicine at NHSGGC, said: "We are pleased that all the cases are recovering at home.
"While there is no conclusive evidence, our investigations have indicated that the most likely source is a link to the consumption of burgers at the SSE Hydro.
"Glasgow City Council Environmental Health Officers have worked closely with the vendors and will continue to liaise with them 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.