The Ministry for Primary Industries (MPI) says it will take two or three months of testing before the two South Canterbury farms hit by Mycoplasma bovis could be declared free of the cattle disease.
MPI, in its latest update, said the number of infected farms remained at two - both of them belonging to the Van Leeuwen Dairy Group (VLDG)
The ministry said it continued to build a picture of where the disease was present, to contain and eradicate it if possible.
MPI's response incident controller Eve Pleydell said laboratory teams worked at the weekend to continue testing the thousands of milk and blood samples from VLDG farms and neighbouring properties. To date 2,610 samples have been received.
"There have been no further confirmed positive test results and the situation remains at two positive affected farms, both in the VLDG," she said.