A British hospital was tracing 24 people on Wednesday who may have been exposed to deadly CJD brain disease - and warned a similar alert could occur in other hospitals under current official procedures.
The patients all underwent operations using instruments which had been used on a person who had a brain operation in July. That patient was diagnosed a month later with sporadic CJD, an extremely rare but fatal brain-wasting condition.
A hospital spokesman said the 24 were at a "very, very low" theoretical risk.
Earlier, the Department of Health was quoted as saying that an "appalling incident" had taken place at the Middlesborough General Hospital in northern England.
As the controversy cast yet another shadow over the UK's National Health Service (NHS), the hospital's medical director defended its handling of the affair.
"We have to take advice given to us about this very rare condition from the NHS authorities, and we appear to have followed the rules precisely," Dr Paul Lawler said.
"It is a terrible incident. Nevertheless it could still happen tomorrow in this hospital or indeed in any other hospital," he added.
"With a patient who was not suspected of having CJD, we would do exactly the same thing - as indeed would any other hospital in the UK," he told BBC television.
Lawler said the 24 may have been exposed to a form of Creutzfeldt-Jakob Disease, known as "sporadic CJD".
British hospital guidelines specify that any equipment used in operations in any suspected CJD cases should be quarantined. But the Middlesborough hospital said there had been no reason to suspect the original patient had CJD.