Hundreds of patients treated by a health care worker diagnosed with HIV and hepatitis B are being recalled.
The infected worker worked at four hospitals in the West Midlands
Letters have been sent to 1,185 people treated in the West Midlands and Southampton over the last six years.
A NHS spokeswoman said it was "highly unusual" to have a health worker contract both infections.
No patient who has had contact with the worker has been diagnosed with the infections but there is a "small risk" of transmission, the spokeswoman said.
Nearly all the patients contacted were treated in the West Midlands with 24 people in the Southampton area also being notified.
The recalled patients are being asked to call confidential help lines and to attend clinics for blood tests.
The worker in question worked in orthopaedics at Redditch's Alexandra Hospital, Kidderminster Hospital, the Orthopaedic Hospital in Birmingham, and Evesham Community Hospital.
A spokeswoman for the West Midlands Strategic Health Authority said the worker had had no symptoms and was unaware of the infections.
The symptoms were picked up by a recent occupational health assessment. Since that time, the worker has not been involved in any work that may place patients at risk.
Regional public health director Dr Rashmi Shukla said: "This is a highly unusual, if not unique, set of circumstances in that the healthcare worker is infected with both HIV and hepatitis B.
"Hospitals have sent letters directly to all the patients who may be affected.
"There is no recorded case of transmission of HIV from an infected health care worker to a patient in the UK and the chance of an infected health care worker passing hepatitis B to a patient is low.
"However there is a chance of infection and I would recommend patients to take the tests if they have received a notification letter."
No HIV screening
Dr Sue Ibbotson, of the Health Protection Agency said following national guidelines, the worker would have been screened for hepatitis B when employed by the NHS.
But she said no such guidelines existed for HIV screening.
New staff are asked if they fall into a high risk category for the virus. If they do, they are tested, but this test is a one-off, and is not repeated regularly during their employment, she added.