Shower water at Starship Children's Hospital is being tested for the potentially deadly Legionnaires disease.
A young girl is battling the disease after being exposed to the bacteria during a long stay at the hospital.
She is in intensive care and other patients in the ward have been tested for the disease, which is a form of pneumonia.
Hospital test results are expected to reveal the source of the outbreak within the next few days.
Legionella is usually caught through infected warm water or soil.
Director of child health Dr Richard Aickin said hot water temperature had been increased from 45 to 65 degrees Celsius to reduce the risk.
"We've been looking at hospital hot water supplies and air conditioning and sending samples to the lab."
He said air-conditioning units have bacteria filters so was unlikely to be the source.
Doctors diagnosed Legionnaires in the child last week.
"This child has been very unwell for a long time with a nasty, underlying condition."
Aickin is reassuring parents and staff that it is an isolated incident.
"The safety of our patients is always our highest priority and I want to make it clear there is no reason for the public to be alarmed. Patients at the hospital had tested negative for the disease."
Tests for Legionnaires on four patients with weakened immune systems came back negative. Aickin said the incubation period has passed without any new cases emerging.
"We are confident this is an isolated occurrence."
This is the first case of Legionnaires disease acquired by a patient at Starship or Auckland City Hospital.
The hospital would not release any further details of the affected patient to protect the family's privacy.
One person died and eight were hospitalised after an outbreak of Legionnaires disease in Canterbury in November.
The affected patients were believed to have been infected while working in their gardens.
- Auckland Now
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