The van Leeuwen's massive robotic dairy shed, the largest in the world, can house up to 1500 cows. The van Leeuwens also have a number of satellite farms in the region.
MPI's regional controller Chris Rodwell said the situation was well under control with support from the affected farm owner and farm managers.
"They're working closely with us during what is a difficult and stressful time for them and I applaud their level of professionalism," he said.
MPI's focus is to identify affected stock and contain the disease. This is being done by isolating the affected farms. The farmer concerned has euthanised a small number of animals voluntarily for animal welfare reasons.
"At this time we are still determining the scale of this situation through on-farm sampling and testing, and tracing of movements of stock on and off the properties," MPI said.
"This will help inform our future management activities which we are currently working up in partnership with the animal industry bodies."
These could include area movement controls, selective culling of some stock or other long term management measures.
Rodwell said MPI's existing activities were sufficient to contain the disease.
"We know other farmers in the area have concerns. This is entirely understandable," he said.
Ministry staff spoke at a well-attended meeting of local farmers in Glenavy this morning.
Rodwell said the disease was a slow-moving one that is transmitted by close contact between animals and not across big distances by wind or water.
Mycoplasma bovis is spread by animal to animal contact and can be present in milk transmitted to other cows this way.
"We need to be clear, though, that the presence of the bacteria does not affect the safety of dairy products for human consumption," Rodwell said.
"This is not a food safety or human health concern.
"We're working closely with the industry to trace and assure supply chains of the safety of product, including products for export."
"It's devastating, especially for the people working on the farm," Aad Van Leeuwen told Fairfax.
"It just hits you and you don't know what to think, you don't know where it comes from."
- with Otago Daily Times