Containing and controlling M. bovis in New Zealand

Containing and controlling the disease

Properties identified through tracing and screening are categorised according to risk of infection, and appropriate measures to contain and control disease are put in place.

Measures include:

movement controls, restricting cattle moving on and off the farm
depopulation
cleaning and disinfection and stand-down period.

Programme property categories

Properties in the programme will fall into one of the following risk categories:

Active Surveillance
Notice of Direction
Confirmed Property (Active or Cleared).

	Active Surveillance	Notice of Direction (NOD)	Active Confirmed Property	Cleared Confirmed Property
Risk of infection	Low risk	High risk	Confirmed infection	Normal
Movement Control applied to the property	None	Notice of Direction (NOD)	Restricted Place Notice (RP)	None (RP lifted)
Programme activity	On-farm testing	On-farm testing	Depopulation, Cleaning and Disinfection	Support recovery and repopulation

Active Surveillance

A farm is placed under Active Surveillance when there is a low risk of infection.

This includes farms that:

sent cattle to a farm which later became infected
are neighbours an infected farm
received cattle from an infected farm before we believe that farm was infected.

These farms are required to undergo testing and the management groups (mobs) of cattle that might have been exposed will be tested to determine their disease status.

There’s no evidence of M. bovis spreading across farm boundaries, unless cattle have mixed or interacted.

The risk is so low that the farms do not need to be placed under movement restrictions.

A very small number of farms placed under Active Surveillance are found to be infected.

Notice of Direction (NOD)

A farm is placed under Notice of Direction (NOD) when there’s a high risk that cattle on the farm may be infected withM. bovis.

This includes farms where:

there are or have been trace animals that have come from an infected herd
a bulk tank milk ‘detect’ test result has been produced
a round of Active Surveillance testing was positive
a farm is closely associated with an infected farm – they share the same owner or manager.

This stops cattle and other high-risk items at risk of spreading M. bovis from being moved off the farm (without a permit), while testing is done to determine if any cattle are infected.

While restrictions are in place, the following cannot be moved off the farm without a permit (issued through MPI):

cattle
milk not being sent for to a commercial processor
equipment that’s been used in the milking environment or has been in direct contact with cattle.

Confirmed Property

A Confirmed Property is either an Active Confirmed Property or Cleared Confirmed Property.

An Active Confirmed Property is a farm with management groups (mobs) of cattle that have been determined to have M. bovis.

A Restricted Place Notice (RP), which is the highest level of legal controls, will be applied to the property. Some main controls include:

cattle cannot be moved in or out of the RP Notice area without a permit
all cattle within the RP Notice area will need to be culled (depopulated)
no at-risk goods/equipment or cattle can be moved out of the RP area, except for cattle being transported to slaughter as arranged by the M. bovis Eradication Programme.

The affected cattle covered by the RP notice will be depopulated (culled).

Depending on the type of farm, it will go through cleaning and disinfection and/or a stand-down period.

Once this has been completed, and movement controls lifted, a farm becomes a Cleared Confirmed Property and can be repopulated with replacement cattle.

Depopulation

M. bovis can be extremely difficult to detect. A seemingly healthy animal can have M. bovis and still infect others. If we confirm the disease in one animal, we have to assume the whole herd is infected with M. bovis. The farm or affected areas of a farm will be depopulated and cleared of stock.

The programme works with farmers to ensure the timing of any cull has the least impact on production.

After depopulation, the infected property will be cleaned and disinfected and undergo a minimum 60-day stand-down period where no cattle will be allowed on the farms.

Surveillance, monitoring and testing remains in place for a time as a further safeguard.

Cleaning, disinfection, and stand-down

After depopulation, each area under the RP Notice will need to undergo:

cleaning and disinfection, and/or
a minimum 60-day stand-down (during stand-down, cattle must not come into contact with areas covered by the RP Notice).

Cleaning and disinfection and stand-down requirements are determined by the farm type and level of risk associated with particular areas and items on the farm.

The aim of cleaning is to remove animal waste, debris, dirt, and organic matter from surfaces.

Cleaning removes most M. bovis bacteria from the environment and allows disinfectants to make effective contact with any remaining bacteria.

The aim of disinfection is to destroy any bacteria that may remain after cleaning. Disinfection is carried out by applying appropriate disinfectants directly onto the surface of an item or area for the recommended contact time to destroy M. bovis.

M. bovis is very fragile in the environment, so a stand-down period enables the natural processes of time, dehydration, warmth, and sunlight to reduce the number of any surviving M. bovis bacteria.

After an infected property has been depopulated, cleaned and disinfected, and had restrictions lifted, a farm becomes a ‘Cleared Confirmed Property’ and can be repopulated with replacement cattle.

Repopulation and recovery

An infected farm becomes a ‘Cleared Confirmed Property’ and can be repopulated with replacement cattle once the property has:

been depopulated
been cleaned and disinfected
completed stand-down, and
had restrictions lifted.

The programme works with farmers on a recovery plan that’s tailored to each individual operation.