Three members of the same family in Belfast have contracted the potentially fatal E-Coli bug, the Eastern Health Board confirmed last night.
A toddler and two relatives, including an adult who needed hospital treatment, were diagnosed with the infection this week.
The child, aged under four, attends Rosetta Primary School. As a consequence the board is expected to screen around 40 children and staff who have an association with the nursery unit.
These new cases come just weeks after the detection of six other cases. Pupils at Brooklands Nursery in Dundonald, Ravenscroft Nursery in east Belfast and Cathedral Nursery in the Lower Falls were all screened after several children were found to have caught the bug.
A spokesman for the Eastern Health and Social Services Board said there was no link between this outbreak and the previous cases saying fears of an outbreak were minimal.
"The overall level of risk to the community is low," he said. " The screening undertaken among small children is due to a higher level of risk of them developing a serious illness from E-Coli infection."
E-Coli can cause diarrhoea and vomiting. In extreme cases it can cause bloody diarrhoea, accompanied by abdominal cramps.