A child has been diagnosed with the life-threatening lung infection Legionnaires' disease at Starship hospital, but doctors believe the infection has been contained.
The young patient, who has a weakened immune system, caught the Legionella bug while staying in one of the hospital's wards.
Starship's child health director Richard Aickin says the child is receiving intensive treatment "and we are giving the family our full support".
Dr Aickin stressed that Legionella does not spread from person to person and tests on other patients nearby have returned negative.
"The usual incubation period has now passed without a second case being identified, so we are confident this is an isolated occurrence," he said.
This is the first such case at Starship. An outbreak in Canterbury last November left one person dead and eight hospitalised.
Legionnaires' disease is a pneumonia-like chest infection usually caught by breathing in Legionella bacteria in warm, damp places.
It is often serious, and 10 percent of sufferers will die.
Symptoms are similar to a severe flu infection and include fever, headache and muscle aches.