Hundreds of women treated at four hospitals in the South East have been warned they may have contracted hepatitis C from a gynaecologist.
Patients contacted are being urged to take blood tests
The 366 women were treated at Frimley Park, Surrey, the William Harvey in Ashford, Kent, and the Conquest and the Buchanan in St Leonards, East Sussex.
They were sent letters on Tuesday asking them to take blood tests to make sure they are free of the virus.
The infected doctor worked at the hospitals between 1983 and 2001.
In total, 2,000 patients from 25 hospitals in England and Scotland have been told of the scare in letters from the Health Protection Agency (HPA).
The infected gynaecologist has been transferred to an area of healthcare where patients are not at risk.
The doctor, who has not been named, did not originally know he or she had the virus, which can lead to chronic liver disease.
At Frimley Park Hospital, 228 women were treated by the doctor, who worked in obstetrics and gynaecology there between 1993 and 1995.
A spokesman said the chances that the virus had been passed on to patients was remote.
In St Leonards, 83 patients treated at the now closed Buchanan Hospital in 1983 and the Conquest in 2000 and 2001 have been contacted.
'Purely a precaution'
"We have worked hard to identify any patient who might have been at risk from this healthcare worker," said Dr David Scott, medical director at East Sussex Hospitals NHS Trust.
"We are offering them screening purely as a precaution."
At the William Harvey, 55 patients treated in 1992 and 1993 have been contacted.
Although hepatitis C does not often reveal symptoms, the virus can cause abdominal pain and jaundice.
In rare cases it can cause cancer of the liver.
Patients at risk have been asked to call a confidential helpline for further information.