There are now 48 confirmed cases of cryptosporidium (up from 45), 12 probable cases, and three are being investigated.
It's been revealed that three people have been admitted to hospital as the disease is transferred from person to person.
Te Whatu Ora/Health New Zealand said drinking water had not been ruled out as the source of the outbreak.
In a statement today, the Queenstown Lakes District Council said its current timeframe for installing the temporary treatment at the Two Mile water supply plant is December 8.
Mayor Glyn Lewers said a plan was now in place and this would provide more clarity about what the solution looks like and when a boil water notice, put in place on September 18, may be lifted.
The council says the UV disinfection equipment is an effective barrier treatment against cryptosporidium for the Two Mile water treatment plant, which supplies the Queenstown network, and is the first step in effective treatment for other non-compliant supplies in the district.
The council's general manager property and infrastructure, Tony Avery, said the first step was to install the UV treatment at Two Mile, but due to a lack of availability of ideally-sized equipment the first intervention would be a temporary solution to address the immediate need and respond to a compliance order.
“This temporary solution will do what we need in the short term but larger UV reactors, which have also now been ordered, are required long term," Mr Avery said.
"Once the larger equipment arrives, we will swap out the temporary systems for use elsewhere in the district. This approach, and taking this opportunity to secure other units, means that we are able to promptly implement UV treatment not only at Two Mile but also water supplies at Western Wānaka, Beacon Point in Wānaka, and Luggate."
The council said the timeframe for implementing the temporary UV treatment has a currently estimated completion date of December 8.
"That ten-week programme included undertaking detailed design, procurement of the component parts and fabrication of the container housing for the equipment, delivery, site connection and commissioning, and flushing of the network.
"Further details of the full programme, including the timeline for installing the larger UV reactors at Two Mile will be provided next week."
The council was trying to isolate the Kelvin Heights water supply network, which has an effective barrier against protozoa such as cryptosporidium, from the Two Mile network. It was working with water services regulator Taumata Arowai to try and lift the boil water notice before the end of the school holidays.
Southern Medical Officer of Health Dr Emma Sherwood told RNZ confirmed cases were being re-interviewed to try and find a definitive link to drinking water or food.
Further testing of drinking water is under way.
Dr Sherwood said some people have been getting it from people they live or work with as a secondary infection, so it is important everyone practices good hand hygiene.
The council statement said it was exploring options with Taumata Arowai that may enable the boil water notice to be completely lifted earlier as current testing of the water supply suggest there is no contamination issue.
Testing of the water supply in the affected area continued to return negative results for the presence of cryptosporidium or other signs of contamination. The extensive sampling and testing programme is ongoing, it said.
“Although Te Whatu Ora is reporting a steady increase in cases of cryptosporidiosis, these can all be linked back to the original outbreak. However, the source still has not been identified and we need to reinforce for now the need for people to adhere to the requirements of the boil water notice but increasingly the indicators point to their being no current contamination issue which is why we are pushing to lift the boil water notice in its entirety as soon as possible.”
On Thursday, Te Whatu Ora Southern advised a number of cases had been identified as secondary infections of cryptosporidiosis, meaning people who have been infected from people they live or work with.
Advice from Te Whatu Ora to minimise the risk of secondary infection is as follows:
- Wash your hands with lots of soap and water for at least 20 seconds and then dry them thoroughly on a clean towel.
- Do not rely on hand sanitizer as this is not effective against cryptosporidium.
- If someone in your household has cryptosporidiosis, ensure all surfaces, including door handles, are cleaned regularly with a cleaning product that contains hydrogen peroxide. Chlorine based products do not work against cryptosporidium and bleach-based products are not as effective.
- ODT Online, additional reporting RNZ
