The South Eastern Health Board has been forced to close a second hospital in the region following a new spate of suspected Winter Vomiting Virus cases.
Four patients and three members of staff at the Sacred Heart Hospital in Carlow have reported symptoms consistent with the virus.
A spokeswoman said:"Tests have been carried out and the patients have been placed in isolation in a bid to curb the spread of the suspected virus".
The health board has appealed to visitors not to come to the hospital, apart from in exceptional circumstances.
Six more people at Waterford Regional Hospital are suspected of having contracted the virus.
Last week, the health board cancelled all non-urgent elective admissions to the hospital following the discovery of suspected cases of the virus.
Thirty-five patients and 64 staff have reported symptoms consistent with the virus. Initial test results have confirmed the presence of the virus in the hospital.