More cases of suspected E.coli O157 infection have come to light among children who attend a Fife nursery.
All four toddlers attend the same nursery in Dunfermline
Four children remain in a serious condition in a Glasgow hospital and all have experienced kidney failure.
Officials have now confirmed that nine further suspected cases are linked to the Careshare Nursery, at Lauder College, in Dunfermline.
NHS Fife said one child was in a local hospital, while seven children and one adult were being monitored at home.
All the children went to the Careshare nursery at Lauder College in Dunfermline.
Letters have been issued to all parents of children who go to the nursery.
According to evidence gathered by the NHS Fife's incident control team, the source of the infection does not appear to be food or water related.
The nursery, which about 100 children attend, has been closed pending the outcome of the investigation.
Three toddlers, all aged two, and a girl aged 22 months, remain in the Royal Hospital for Sick Children in Glasgow.
Two of the sick toddlers, Lorna Balfour and Abigail Young, are children of students at the college.
Dr Jackie Hyland, of NHS Fife, said: "It's not unexpected that we see further possible cases coming forward because we have sent letters out to parents asking them to be alert to the symptoms of diarrhoea and vomiting.
"According to the information and evidence so far, it does not appear to be a link between food and drink.
"In this case we are perhaps seeing a person to person spread, although we don't know what the original source is."
An incident control team involving NHS Fife, Health Protection Scotland, Fife Council, Food Standards Agency and others is meeting daily to investigate the possible cause of the outbreak.