The testing involves the collection of samples from up to 200 horses at 340 properties in each of the six divisions which make up the zone.
Samples were also collected from a total of 210 horses at seven horse studs.
More than 17,000 test samples were collected throughout the zone during January. Forward Command Posts throughout the purple zone have held 36 clinics attended by more than 3000 horses, enabling the completion of the first round of vaccinations on schedule.
The second round of vaccinations is expected to be completed by 29 February.
The proof-of-freedom freedom is on track to allow the change to green status by mid-March.