A fifth Van Leeuwen Dairy Group farm has tested positive for bacterial cattle disease Mycoplasma bovis.
Yesterday, response incident controller Stephen Bell said in a statement the possibility of more farms in the VLDG operation testing positive had always been ``fully expected''.
``The nature of this disease is that it spreads between animals that are in close, repeated and prolonged contact.''
A farm in the Oamaru area and a lifestyle property in North Canterbury have also previously tested positive for the disease.
The newly identified property was already under a restricted place notice under the Biosecurity Act.
More than 26,000 of the planned 39,000 tests had now been completed by the Ministry for Primary Industries' animal health laboratory in Wallaceville.
Those tests had been focused on the infected properties and stock movement traces to and from those properties and neighbouring properties. No neighbouring properties had been identified as infected yet.
A multilayered approach to testing had been taken to determine how widespread M. bovis was, including district-wide surveillance in the Waimate and Waitaki districts.
All those results were now back and no further infection outside the Van Leeuwen Group had been found.
There had also been a nationwide testing programme and samples of mastitic milk had been collected from regional laboratories across the country.
About 2300 samples had been received and tests had also not identified any other infected farms elsewhere in the country.
Those results were encouraging and suggested the MPI's surveillance plan was working and the disease was not spreading in the local area around the infected farms and was not widespread across the country, Mr Bell said.
The MPI was preparing for ``what might happen next'', which involved preparing plans for different possible scenarios.
``Eradication is one of the scenarios we are looking at but, before we can make decisions, we need to have enough evidence to be confident that the disease has not spread elsewhere.
``We cannot make long-term decisions that potentially have huge impacts on people's lives without that knowledge. We need to be confident the disease is limited to the outbreak on the farms where we have detected it,'' he said.
The MPI hoped to have a ``clear picture'' by mid-October. If samples continued to test negative and if the evidence was pointing to the infection being contained to the current properties, it would expect to have sufficient confidence to assess whether the disease could be eradicated.
