A Perthshire nursery school is at the centre of a three-day deep clean after a suspected case of E-coli was detected.
Health bosses say suspected symptoms were detected in a child with links to Errol nursery and stressed the risks to the wider public were very low.
NHS Tayside and Perth and Kinross Council are investigating how the infection may have come about.
The school remained open while the nursery area was cleaned thoroughly overnight on the advice of public health experts. Council chiefs insisted the operation by Tayside Contracts was being carried out as a precaution.
The health board wrote to parents last week to say experts were investigating a single case of suspected Escherichia coli, more commonly known as E. coli.
The germs are commonly found in farm animals and can cause sickness, diarrhoea and a fever in humans.
An NHS Tayside spokeswoman confirmed yesterday the infection was in a nursery pupil and that investigations are ongoing.