Health officials are trying to trace 134 babies after it was revealed that a doctor who treated them has tuberculosis.
The hospital where the doctor worked for six weeks has now begun contacting patients and has arranged special clinics.
But medical chiefs stressed at a news conference today that the risk of infection was "minimal".
The unnamed doctor was working in the neo-natal unit at Leicester Royal Infirmary when he was diagnosed as having TB.
The ward cares for vulnerable babies who, with no natural immunity against TB, are highly at risk.
A Leicester Royal Infirmary spokesman said the doctor had cared for or checked a total of 134 babies during the six-week period he was working at the hospital.
He was now on sick leave and receiving treatment.
Nick Naftalin, acting medical director of the University Hospitals of Leicester NHS Trust, said that the doctor joined in February and was diagnosed as having TB at the end of March.
Efforts were now being made to trace other people, including patients, with whom who he came into contact.
"We recognise that the patient population that this doctor was caring for are particularly vulnerable and we would recognise also the anxieties of the parents whose babies have already been on the neo-natal unit," he said.
The junior doctor worked in another hospital before joining Leicester Royal Infirmary, and as the incubation period for TB is up to 12 weeks any places he worked previously were being contacted.
Dr Philip Monk, consultant in public health at Leicestershire Health Authority told the news conference: "The doctor has worked elsewhere and the places where he has worked have been notified.
"In cases like this the process of contact tracing is made to try to determine when the disease started. We don't know when this doctor became infected and whether there is a risk elsewhere."
There had only been one other case of a junior doctor working in a neo-natal unit contracting TB in Britain, and that was seven years ago at an undisclosed location, he said.
Special clinics have been scheduled for Friday this week and Monday next week so parents can take their babies to discuss the situation.
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