The HSE has confirmed that 12 cases of E.Coli have now been confirmed, following an outbreak at a creche in Dunmore, Co Galway.
Four of these people were hospitalised.
The outbreak occurred at the Dun Beag Creche in Dunmore, which has been temporarily closed.
The HSE's Outbreak Control Team is continuing to investigate the E-Coli outbreak.
In a statement, the HSE says it has met with creche management and appropriate control measures are being undertaken.
This strain - E.coli VTEC - can spread in a number of ways including contact with infected animals, contaminated soil, water or certain foods and can be spread among toddlers who are not toilet trained.
Last year, 927 cases of VTEC were notified in Ireland, and the HSE says the number is increasing each year.