International science expertise to help eradicate M. bovis

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Global epidemiology consulting company Ausvet and New Zealand's Working Formula (WF) have been appointed by the Mycoplasma bovis Programme (The Ministry for Primary Industries, DairyNZ, and Beef + Lamb New Zealand) to undertake research to help accelerate eradication of the cattle disease from New Zealand.

Ausvet and WF specialise in finding disease patterns in populations. This knowledge will help us understand the risk of spread from different properties at different times, explains Dr John Roche, MPI's chief science adviser and chair of the M. bovis Strategic Science Advisory Group (SSAG).

"Farms potentially infected with M. bovis are currently prioritised for follow up (casing) using several criteria. Ausvet and WF will investigate if there is anything we can do to improve the current criteria to more effectively prioritise farms at high risk of infection for urgent follow up.

"It's more critical to apply movement controls on high-risk farms than other properties. If these farms can be identified and actioned more quickly, it will slow the spread of the disease and speed up eradication."

This will be a short-term research project, based on analysis of existing data.

Ausvet has also been awarded a contract to review the existing M. bovis Programme surveillance strategy. This will identify any areas for development and improvement focused on how to improve our confidence that M. bovis is absent from New Zealand in the future. The company will also provide training to M. bovis Programme epidemiologists, so that they can perform the analysis of the surveillance strategy on an ongoing basis as needed.

Dr Roche says that this ongoing background surveillance of the different cattle sectors is a vital component of New Zealand's eradication effort. There will be ongoing surveillance for at least 7 years following identification of the last known infected property. An effective surveillance programme is what will provide assurance that M. bovis is absent from New Zealand.

These 2 projects support recommendations made in a recent Technical Advisory Group report into the M. bovis Programme. They have been identified as priorities in the M. bovis Science Plan, developed by the SSAG with input from a wide range of experts to ensure research is directed where it will most effectively accelerate eradication of the disease from New Zealand and minimise the negative impacts on farmers and rural communities.

The M. bovis Programme has allocated up to $30 million for M. bovis research projects. This is part of the $870m in funding allocated to eradicating M. bovis.

Proposals to undertake several other science plan projects are currently being evaluated, including a major diagnostic research programme.

Question and answers

Risk prioritisation research

What is the aim of this research project?

To determine if there is a better way of prioritising farms potentially infected with Mycoplasma bovis.

This would enable the M. bovis Programme to more effectively prioritise follow up casing of high-risk properties that will likely need animal movement controls applied to help accelerate the eradication of the disease.

When would a property be identified as potentially being infected with M. bovis?

Usually when the M. bovis Programme's tracing of cattle or milk from infected farms suggests a farm may be at risk. This is likely to be because the farm has received animals or milk from a farm that is known to be a confirmed case.

What does casing involve?

The M. bovis Programme contacts a farmer to confirm cattle movements and verify farm data and other details as necessary. Casing information is reviewed to determine what action is required. This can include a Notice of Direction (which is a legal order restricting movements of animals and other risk items off the farm), or testing without movement controls if the risks are low and the Programme wants to rule out the presence of disease, rather than expecting to find it.

How does the M. bovis Programme prioritise properties for casing now?

Properties currently identified as having the highest M. bovis infection risk and, therefore, the highest priority for casing, are those that:

  • received cattle or milk from a property confirmed as being infected with M. bovis during the time it was infected, and/or
  • dairy farms that return a 'detect' result on bulk tank milk tested by ELISA, which detects antibodies to M. bovis.

What additional risk factors could be factored into an improved risk-assessment model?

This is the key question we are wanting the research to answer, but some additional risk factors could potentially include:

  • the number of animals that have been moved onto a property – a movement of 100 animals has a greater chance of including an infected animal than a movement of 10 animals, particularly for beef properties
  • timing in relation to the farming production calendar – this could identify periods where the risk of further animal movements off farm is greatest in the different enterprises and in the different regions, i.e. movements off farm vary by time of year, enterprise type, and region.

How will Ausvet and WF undertake this work?

Ausvet and WF will analyse existing data collected as part of the M. bovis Programme – no new data will need to be collected from farmers.

Will this research directly result in movement restrictions being placed on farms?

No. This research is aiming to make the current casing prioritisation system more efficient in order to slow the spread of the disease and speed up the eradication.

Epidemiology surveillance review

What is the purpose of this review?

This review will ensure that the M. bovis surveillance programme is optimised now and in the future. It will review the performance of all the surveillance streams and highlight areas that require additional surveillance and those that could be scaled back. This continuous improvement using information collected by the programme is essential to tailor our approach to the unique New Zealand farming system.

What elements does the current surveillance programme include?

It is made up of multiple surveillance elements such as bulk tank milk testing, mastitic milk testing, meat processor surveillance, aggregator surveillance, and cow-calf surveillance.

What outcomes could result from this this review?

The review may identify that additional surveillance streams are warranted in some sectors.

In addition, the review will give us more information about the expected duration of background surveillance following identification of the last known infected property. This will enable us to compile sufficient evidence to say with confidence that M. bovis is absent from New Zealand.

As part of this review, Ausvet will deliver training to M. bovis Programme epidemiologists so that they can perform the same surveillance analysis in-house in future, on an as-needed basis.

How long will the review take?

It will be completed in 3 to 4 months.

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