Dublin's Beaumont Hospital is expected to confirm later today that one of its kidney dialysis patients has tested positive for Hepatitis B.
If the positive test is confirmed, the hospital is expected to offer screening to around 200 people who would have used the same dialysis machine as the infected patient.
Hepatitis B is a serious disease caused by a virus that attacks the liver. It can cause a life-long infection, liver cancer, liver failure and even death.