A member of staff contracted tuberculosis

A worker at Altnagelvin Area Hospital's Accident and Emergency Department was found to have contracted the respiratory disease.

Dr Richard Smithson, a consultant in Communicable Disease at the Western Health and Social Services Board, said the risk to patients was almost non-existent.

However, he said the board felt it was important to inform patients that they had been in contact with an infected person.

This is about being open and honest with patients and informing them about what has happened Dr Richard Smithson disease expert

Dr Smithson said: "We have gone through all the records and identified every patient who would have had contact with this member of staff.

"Letters have been sent out to them and should be arriving with patients this morning.

"Anybody who doesn't get a letter can be assured that they were not in contact with this member of staff."

Patients' general practitioners have also been notified.

Dr Smithson said it was not possible to say where the staff member had contracted the disease.

He stressed that Northern Ireland has one of the lowest levels of TB infection in the world but cases "can arise from time to time".

Referring to the letter sent to patients, he said: "This is about being open and honest with patients and informing them about what has happened.

"We have set out the signs and symptoms of TB in the letter and we have told them what to do if they do develop these and are at all worried.