Thousands of people across the UK are being contacted after a healthcare worker infected two patients with the Hepatitis C virus.
A major alert is under way after it was discovered that a retired obstetrics and gynaecology worker unknowingly had the virus while employed by the NHS for decades. It is known the healthcare worker infected two patients with the virus while working at a hospital in Wales, Public Health England said.
At least 3,000 former patients are being contacted by letter informing them of the risk and a series of confidential helplines and a support service have been set up. Several hundred patients in other areas of Wales who may have come into contact with the health worker are also being contacted.
In England around 400 former patients are being contacted, while urgent steps are being taken to check historic patient records in Scotland and Northern Ireland.
"It has recently come to light that the healthcare worker is known to have transmitted the virus to two patients while working at a hospital in Wales from 1984 until they ceased clinical practice in 2002," a spokesman said.
"A 'lookback' patient notification exercise involving the review at least 3,000 former hospital patients' notes and records from the Caerphilly District Miners Hospital has been announced by the Aneurin Bevan Health Board today.
"Around 200 former hospital patients from two other hospitals in Wales where the healthcare worker practised for a short time are also being contacted.
"Those patients identified as exposed or possibly exposed to Hepatitis C are being sent individual letters and asked to call a special confidential helpline, inviting them to attend a hospital clinic or, if they have moved away from the area, their GP for a blood test."
He added: "Effective treatments are available for Hepatitis C and further information and advice will also be provided to anyone who needs it. There is only a small chance that a patient might acquire Hepatitis C virus infection through surgical contact with an infected healthcare worker."
The healthcare worker is known to have worked at other hospitals across the UK prior to working in Wales, including 11 hospitals in England from 1975 to 1983.