BBC News reports that two girls who attended a dance camp in Pembrokeshire have contracted E.coli, it has been confirmed.
An 11-year-old from the West Midlands is being treated in hospital and a seven-year-old from Denbighshire is recovering at home.
Both had attended Dance Camp Wales in Cresselly, which runs between 29 July and 9 August.
Social networking website Facebook is being used to try to contact about 650 people who attended a dance camp after two girls contracted E.coli.
Environmental health officials are also sending letters, e-mails and phoning, where they have contact details.
A spokeswoman said they had turned to Facebook because the event has its own group on the website.
People who experience symptoms are asked to contact Pembrokeshire council’s public protection department on 01437 764551 (between 1000 BST and 1800 BST on weekends and between 0800 BST and 1800 BST on weekdays) or email firstname.lastname@example.org.