A health board is trying to identify a person who may not know they are HIV positive after finding the virus in a blood sample.
NHS Highland has contacted a small number of patients who had blood taken at Raigmore Hospital in Inverness early last year.
HIV was identified in one of the samples, but the health board said the positive result detected did not relate to the patient from whom the sample was taken.
Further research revealed the sample could have been contaminated by another person’s sample in a laboratory.
The health board said it has not yet been possible to identify the source of the positive HIV result, adding it believes there is a patient with an undiagnosed HIV infection.
Dr Boyd Peters, NHS Highland’s medical director, said he “sincerely apologises for any stress and anxiety” the discovery may cause to patients and the wider community, and added the health board can offer treatment and support to the patient if they wish.
He said staff are offering an HIV test to patients who had blood samples tested in the laboratory during a similar timeframe through a special patient notification exercise.
“Letters have been sent to those individuals included within the exercise to provide them with specific advice and to offer HIV testing,” he said.
“Testing for HIV involves a blood test which is provided free of charge with results available within a couple of days.”
Dr Peters said the health board has a team of advisers who will provide practical support, guidance and advice to everyone involved in the process.
It is estimated that there are around 500 people living in Scotland who are unaware they have the infection, approximately one in every 10,000 people, according to NHS Highland figures.