A child attending the Craigneuk Nursery Centre in Wishaw is recovering at home in North Lanarkshire after contracting a strain of the E.coli O157 infection.
The Craigneuk Nursery Centre cares for 130 children and so far no other cases have been reported.
A NHS Lanarkshire, spokesman who refused to reveal the child's age or sex, said all staff and parents of children had been contacted as a precaution.
A spokesman for NHS Lanarkshire said: "The public health department of NHS Lanarkshire is investigating a single case of E.coli O157 in a child who attends Craigneuk Nursery in Wishaw. The child is recovering at home.
North Lanarkshire Council has started investigating the case.
"As a precaution staff and parents of children who attended the nursery during August are being contacted.
"The advice is that anyone who has been vomiting or had diarrhoea, especially bloody diarrhoea, in recent weeks should contact their GP.
"The investigation by NHS Lanarkshire and North Lanarkshire Council is ongoing."
Thursday and Friday were declared as holidays for the nursery as the centre held in-service days to prepare for the new term.
According to North Lanarkshire Council education officer Ray Murphy, "We can confirm that one child who has attended Craigneuk Nursery Centre in Wishaw has been confirmed as having an E.coli infection.
"Members of staff and parents of children that attended the nursery in the last three weeks will be contacted to advise them of the situation and provide them with relevant information.
"We will continue to work with NHS Lanarkshire to gather more information on this matter. In the meantime, we wish the child a speedy and full recovery."
14 cases of E.coli O157 were reported at a nursery in Dunfermline in May.