Medical officer of health Dr Susan Jack shared the information yesterday, adding there were now 45 confirmed cases of Cryptosporidium (crypto), 17 probable cases and three under investigation.
A source of infection was yet to be identified.
"We are working closely with Queenstown Lakes District Council, Taumata Arowai and the Ministry of Primary Industries to ensure all possibilities are being considered," Dr Jack said.
"Public health are aware of some cases of secondary infection of crypto.
"This means that there are some people who are getting it from people they live or work with.
"It is very important that everyone practise good hand hygiene to stop the spread of crypto to other people."
Dr Jack confirmed three people had been admitted to hospital for crypto since the outbreak began.
All of them had been discharged.
A boil water notice remained in place for much of the Queenstown township.
Taumata Arowai head of regulatory Steve Taylor said it had written to councils that had drinking water supplies without a protozoa barrier, sourced from either surface water (river, lake, stream or spring) or a bore with a depth of less than 30m.
"We are asking these councils to ensure the information they have given us is accurate and up to date by October 4.
"Once they have had the opportunity to do this, we’ll release a list of supplies that don’t have the necessary protozoa barriers in place.
"We have indicated to councils that we will shortly communicate our expectations of compliance and the timeframe for getting protozoa barriers in place."