An outbreak of Legionnaire's disease in Auckland is thought to be over with the number of reported cases dropping back to normal levels.
The disease contributed to two deaths during the health scare between February and July, and 17 people were infected.
However, there have been just two reports of the disease in the last 78 days.
Auckland Council issued urgent health advice earlier this year telling people to shock-dose their air conditioning systems and water cooling towers.
The cooler autumn and winter weather is thought to have helped get rid of the bacteria.
The source of the outbreak has not been identified despite an investigation, and it is now believed it may have come from more than one location because of the widespread nature of the reported cases.
"Legionella bacteria occur naturally in the environment and can reach levels dangerous to people," Medical Officer of Health, Dr Simon Baker said.
"The Lp1 sub-species is commonly found in warm water systems. This outbreak indicates that maintaining cooling tower surveillance and treatment is of paramount importance."
During the outbreak Auckland Council made contact with around 600 building owners who had water cooling towers, and officials say the experience gained in dealing with the emergency could be useful in the future.
"Having more complete knowledge about the locations of cooling towers in the region will allow the public health team to identify and contain specific locations more quickly, if a new case is reported," building control manager Ian McCormick said.
A number of Government departments are now reviewing the response to the outbreak and what lessons can be learned for the future.