Rapid tuberculosis testing has been set up to screen hundreds of staff and patients of Sydney's St Vincent's Hospital following the detection of a cluster.
The hospital said the cluster started with a patient treated for asthma and pneumonia at the hospital last October who was diagnosed with tuberculosis (TB) several weeks later.
That patient is thought to have infected three other patients and a staff member while at the hospital.
St Vincent's Respiratory Physician and tuberculosis specialist Anthony Byrne said testing had since found all five cases to be the same strain.
"Usually with tuberculosis you need prolonged close contact and we are talking hours or in fact days and the people most at risk when someone has active tuberculosis are people that are usually living with the person so household contacts are people that would be most at risk usually," Dr Byrne said.
Standard treatment for TB involves isolating the patient and placing them in a negative pressure room while all treating health care personnel wear additional protective clothing and equipment.
Dr Byrne said NSW Health and St Vincent's were now "casting the net wide" by testing members of the public in addition to staff and patients who were at the hospital at the same time as the initial patient.
But the hospital stressed that the risk of infection was low.
Preventative therapy is already being offered to some people.
Dr Byrne said Australia had a low TB incidence rate of 7 per 100,000 annually, which meant about 600 people in NSW were diagnosed per year.
But despite the low rates here, it was still "a worry" globally.
"TB didn't get the memo about what is happening in the world today and other problems such as COVID," Dr Byrne said.
