Hundreds of hospital patients have been asked to undergo testing after it was found a healthcare worker who treated them may have been infected with HIV.
Three hospitals trusts in North and East Yorkshire have written to a total of 519 people, although they have stressed the risk of infection is extremely low.
Managers said they removed the member of staff involved from duties as soon as they were aware of the situation, according to NHS North Yorkshire and York.
A spokesman said: “The individual no longer works in a role where there is any risk of blood to blood contact.”
He or she spent time working at Hull and East Yorkshire Hospitals Trust, Scarborough and North East Yorkshire Hospitals Trust and York Hospitals Foundation Trust.
A total of 371 patients have been written to in Hull and East Yorkshire, 47 in Scarborough and North East Yorkshire and 101 in York.
The patients who have been sent letters underwent particular types of procedure, the trusts have said.
Dr David Hepburn, medical director at Hull and East Yorkshire Hospitals Trust, said: “Some 519 patients are expected to receive letters today informing them that a healthcare worker who has been involved in their care has the HIV infection.
“Recalling patients for testing is purely a precautionary measure. It does not mean that the infection has been passed on. The risk to patients is extremely low.
“We are offering testing to patients purely as a precaution.”
Dr Hepburn said it was important to remember that no case of HIV cross-infection from healthcare worker to patient has ever been found in the UK despite almost 30 similar patient recall exercises involving well over 7,000 people.
He said there have only ever been three reported episodes of this happening in the world.