The other three were within a farming enterprise in Winton. MPI also suspected a property near Ashburton was affected.
MPI response director Geoff Gwyn said early indications were that all the properties had links with the van Leeuwen Dairy Group through cattle movements.
“The Hastings and Ashburton properties were identified through our tracing programme and the Winton property was identified through the industry milk testing programme.
“All of the movements we have been tracing are prior to July 21 when the disease was first detected and notified to MPI.”
The Hastings and Winton properties were under a restricted place notices, effectively placing them in quarantine lockdown and restricting the movement of animals and other risk goods on and off the farms.
The suspect property was under voluntary movement controls until its status was confirmed. MPI was working closely with it.
Gwyn said the new developments were not good news.
“We’re still analysing what this means for the wider response.
“We’re dealing with a lot of uncertainty.
“Our investigators are building a picture of stock movements onto and off these farms so we will not be making hasty decisions on next steps.
“While it’s really disappointing to have these new properties, it is not totally unexpected.
“We know that this disease is spread through contact between animals and through the movement of stock – as is the case here.
"It was always possible further infected properties would be found, buying, selling and moving stock is a common practice in farming.
“A key part of our response has been identifying and investigating animals that have moved to or from affected properties before Mycoplasma bovis was first detected. This tracing is complex detective work which takes time.
“I know an obvious question people will have is ‘Why has it taken this long to find these properties?’ The answer to that lies with the nature of this particular bacteria.
“It is a tricky thing to find and often hides within an animal, lying dormant and not revealing itself for weeks or months.
“Some cattle may be infected and never show signs of the disease.
“This is why we test multiple times using multiple kinds of tests. Sometimes to confirm the disease we have to test organ tissue from animals at slaughter as was the case in Hastings.”
Gwynn said the depopulation programme was almost complete on the infected van Leeuwen properties and was on track to be completed before Christmas. To date more than 3500 animals had been culled.
“Our extensive testing and tracing work also continues.
“So far the MPI lab has completed over 55,000 test and our investigators have followed up 250 properties around the country.
MPI would hold a public meeting in the Hastings area on Wednesday December 20. The time and venue were to be confirmed. Details would be put on the MPI Facebook page facebook.com/MPIgovtnz.
