The number of properties in New Zealand under regulatory control for the Mycoplasma bovis disease has leapt from 129 to 299 in just six days.
There are 38 infected properties currently, with two more found this morning, one in Oamaru and one in Southland.
On top of that, there are 40 properties which are highly likely to become infected.
Head of Biosecurity New Zealand and chief operations officer Roger Smith spoke today to the Select Committee briefing into Mycoplasma bovis, and said in the last six days the spread "has gone totally above all expectations".
The biggest change in the last six days has been farms under a notice of direction.
That means the farms are at risk of spreading the disease so farmers need permission to move stock.
There are also 1700 farms that officials are keeping an eye on.
About 11,000 animals have already been culled, with that number expected to double.
Mycoplasma bovis can cause untreatable mastitis in cows, severe pneumonia for 30 per cent of calves, swollen joints and severe arthritis. It does not infect humans, but can be spread through close contact between cattle or on contaminated equipment.
It does not pose a food risk to humans.