The same strain of Legionnaires disease that killed one man and infected three others in the Manukau City community of Beachlands was also found in nearby Maraetai.
An 80-year-old man died in February and three other people in the small seaside community tested positive for the disease but recovered.
A
report released yesterday by the Auckland Regional Public Health Service into the outbreak said that five households and a waterblaster in daily use at the marina tested positive for the same type of legionella. A total of 48 households were tested.
A sample taken from a household in the nearby community of Maraetai in July also tested positive for the same strain as the Beachlands samples.
The report, the first into Legionella contamination of roof-collected rainwater in this country, could not establish the source of the outbreak.
However, medical officer of health Dr Greg Simmons said it was a possibility the waterblaster was the source of the outbreak.
"It is possible that aerosols containing Legionella discharged to air by the waterblaster may have seeded the nearby Beachlands roof-collected rainwater systems. It cannot be excluded that contamination from the waterblaster in Beachlands could be carried as far as Maraetai," he said.
"Alternatively, what we may be seeing is a predominant strain in the region."
All affected water systems have since been disinfected and cleared of contamination.
Dr Simmons said limited resources had prevented every household being tested.
"It's more important to focus on correct maintenance and cleaning of the system rather than deciding whether you might have legionella in your water supply today, and if it isn't there today, what's to stop it being there tomorrow if you aren't cleaning or disinfecting it."
The report said that few households were maintaining their tanks regularly.
It emphasised the need for residents to keep their water tanks clean and treat their water to reduce the risk of contamination.
Brochures from the Ministry of Health detailing the maintenance of water tanks have been distributed.
Legionnaires disease is a respiratory infection caused by the legionella bacterium. It is contracted by inhaling a mist of infected water.
