Mycoplasma bovis update: 13 June 2018
Wednesday, 13 June 2018
This update includes:
- Update from the CEO - what NZVA has been doing regarding M. bovis
- Limits of commercial testing means on-farm risk assessments needed
- NZVA sets up M. bovis Steering Group to support members
- Source of infection and triggers for review
- Information events for farmers
- Some key points to reinforce with farmers
o Biggest risk factors are animal movement and raw milk
o Clean muddy gear and vehicles before you disinfect
o Pet days present challenges so risks must be managed
You are welcome to share this information with others, including your farming clients.
Update from the CEO
This updates you on what NZVA has been doing to support members working with rural communities and to support the government/industry to develop their M. bovis eradication plan.
Over the last fortnight our Chief Veterinary Officer Helen Beattie, our President Peter Blaikie and I have met with industry representatives, MPI officials and MPI Minister Damien O’Connor. At these meetings we’ve been upfront about our belief that eradication is a big ask, but that we’re willing to support the government/industry decision to attempt it.
Where relevant, we’ve offered technical insights to support development of the eradication plan. We have also discussed the specific role veterinarians might play in implementing it.
We will continue to be involved in these conversations as government/industry work through the details in the coming weeks.
Helen, Peter and I have also been talking to members around the country, and this week Helen will be attending events in the South Island for members and farmers.
I am very mindful that the uncertainty and information gaps that result from planning processes like this can be frustrating for farmers and veterinarians. But we will try to give you as much verified information as we can, as soon as we get it.
If you have insights into what’s happening on the ground, or have issues you want to raise, please contact us at firstname.lastname@example.org.
New Zealand’s veterinarians will continue to play a huge part in addressing this cattle disease, as we have done in the past for other diseases. We are poised for the profession to demonstrate value through your numerous roles in private practice, farm advisory, research, innovation, communication, analytics, pathology, animal remedies, education and all parts of government. Most of all, it is time for leadership across our association.
I look forward to talking with you at next week’s mega conference in Hamilton – this is the largest gathering of national veterinarians New Zealand has ever seen. The multi-disciplinary topics, speakers and events are absolutely not to be missed.
I would like to finish by assuring all members that despite the high priority of these initiatives below, the progress of every other NZVA priority is just as important to us. A huge amount of work gets done across the association that does not always get ‘airtime’ in the same way.
Chief Executive Officer, New Zealand Veterinary Association
Limits of commercial testing means on-farm risk assessments needed
As previously shared with the membership in an email, the NZVA believes that a 2-step process, consisting of an on-farm risk assessment, with subsequent testing if required, is the best way to assist farmers to understand their risk with respect to Mycoplasma bovis. We understand that there is a strong desire from farmers for access to testing because of the belief that it will resolve uncertainty about their herd’s status. But it’s time to educate farmers that no one test can do this.
As discussed in this email there are significant limitations with M. bovis testing, particularly when testing is done in an ill-considered way. This includes testing a low risk herd – if tested you will invariably find false positives. False positives (which will overload the response) and false negatives (which could perpetuate disease spread) are a reality with this organism and all currently available tests.
The list below sets out the variables that need to be considered when testing and interpreting results:
- The right animal (animal is infected – i.e. random sampling will select some infected animals)
- The right time (animal is shedding/seroconverted)
- The right place (if PCR is used, is the animal shedding from chosen surface; i.e. nasal vs preputial – animals may not shed consistently from all surfaces)
- The right test (PCR +/- ELISA – antibody vs antigen; time from infection/antibody persistence/has M. bovis been cleared, or not?)
- The right regime and numbers (sampling protocol – must include every cohort, in correct numbers)
For these reasons, the NZVA has advocated strongly for an on-farm risk assessment to be developed and used in conjunction with any testing that may be offered. Remember that (false/suspect) positives must, by law, be referred to MPI’s exotic disease hotline (0800 809966), and a false negative can have significant downstream implications (i.e. forward traces), and potentially leave our profession vulnerable and exposed for having provided advice.
If, based on the outcomes of a risk assessment, a farm’s risk status is low, testing is unlikely to add any further value. Given all of this, we strongly advocate for the risk assessment that is under development to be widely used. Testing will likely only be available as a sequelae if the risk indicates that it may assist in understanding a herd’s status.
Remember also, that risk can only be considered at a herd level – it is not possible to accurately assess risk at an individual animal level, given the constraints of the organism, and testing. Remember also that most herds in New Zealand are not infected with M. bovis.
We’ve engaged and driven the conversation about the value of such a tool with MPI, industry and government, including the pivotal role that veterinarians will have in this process. We have many existing relationships with farmers, access to herd health history and an understanding of farming practices used on many individual farms. All of this is important in providing support to farmers and mitigating stress, by providing a standardised approach to risk assessment and use of tests that fit with the response requirements (i.e. results can be used and analysed by MPI as needed, and do not need to be repeated).
Assessments need to be done rigorously, to a consistent standard across the country, to ensure all data collected are robust and comparable. A standardised approach will help farmers understand farm-to-farm trading risks, and in addition to supporting the eradication effort, these assessments would help reduce anxiety for farmers by providing them with more certainty about their situation.
We will keep you updated on developments.
NZVA sets up M. bovis Steering Group to support members
To help ensure members have access to the best information about M. bovis, we are bringing together a strategic advisory panel convened and chaired by our NZVA President Peter Blaikie.
This panel will comprise members with knowledge of M. bovis and diverse expertise in dealing with outbreaks of other similar diseases. A number of specific sub-committees will be established to design and drive the aspects of the vet-led response.
It will help us provide members with up-to-date and practical guidance. It will also help us provide the best advice we can to the industry and government.
Source of infection and triggers for review
There has been some discussion in the media about the source of the outbreak, and whether this could have been via European-sourced semen, imported in late 2014 or even earlier.
MPI’s current position, that all infections can be traced back to one farm, has also been questioned.
This discussion is not surprising. The source of the infection and the strength of traceability of all outbreaks back to a single infected farm have significant implications for how widely the disease might have spread by now. It also has implications for the feasibility of any eradication goal/programme.
MPI Minister Damien O’Connor has been quoted in the media as saying that “indications at this stage are that it’s not the Australian strain, it’s more likely the European one.”
MPI’s position continues to be that traceability back to an index farm is robust for all currently known infected and restricted properties.
There are ‘hard triggers’ that would potentially prompt a review of MPI’s position, and the feasibility of the eradication plan, which include:
- Multiple strains being discovered
- A lack of traceability – positive herds where no links to existing infected properties can be made.
- The number of cases grossly exceeds that which is predicted and is beyond the current scope of the eradication plan.
Again, as more information comes to hand, we will provide this to you.
Information events for farmers
MPI and the industry are working to set up information events for farmers.
We are still awaiting details of exactly where and when these events will be held. But we will share this information with you as soon as it comes available.
Some of the events appear to be being held at quite short notice, so it might pay to monitor MPI’s social media, along with that of DairyNZ and Federated Farmers.
Where appropriate, we will try to have members available to talk at these events to provide farmers with information and to answer their questions, if we can’t be present ourselves.
Events we are aware of are running in Ruapehu, Wairarapa and Masterton.
Some key points to reinforce with farmers
Below are some important points veterinarians can reinforce with farmers and others living and working in rural communities.
Biggest risk factors are animal movement and raw milk
A key role for veterinarians is to educate farmers about risk factors that make them vulnerable to M. bovis. This conversation will flow out of the risk assessment as farmers are made aware of their on-farm risk behaviours and practices.
While the key risk factors have been well publicised by MPI and the industry, it is useful for veterinarians to reinforce them when talking with farmers.
- Movement of animals
Farmers should limit cattle movements onto their farms and avoid their animals coming into contact with their neighbours’ animals. Double-fencing boundaries is a sensible pre-caution. Accurate NAIT is required, and animal movement history should be considered before new stock is introduced.
- Feeding raw milk
Milk from infected cows that is fed to calves is the other key risk factor in transmission of M. bovis. NZVA advocates for no between-farm milk movements as this is key to reducing transmission of M. bovis. Milk movement is not recorded in New Zealand, and as a consequence presents a real challenge in the response tracing. NZVA strongly recommends that if milk is transported between farms, this movement is always linked to calf movement between the same farms. This means calf NAIT tracing will be a proxy for waste milk tracing (which is currently unregulated and untraced) and the risk profile for farms would be the same.
Ideally farmers would only feed milk from their own farm to their own calves.
Introduction of milk from outside sources should be considered very carefully. Cows shed M. bovis intermittently so prior bulk milk test results are not a robust way to gauge a farm’s status, and even less so a cow’s individual status. Shedding is more likely at times of stress (i.e. during transition).
Clean muddy gear and vehicles before you disinfect
It also important to remind farmers that disinfectants won’t work through dirt. Farmers need to remove all organic matter from gear and vehicles BEFORE they disinfect. Once items are clean, using a disinfectant is only useful if mixed correctly and correct contact time is achieved.
With some disinfectants, this may be up to 10 minutes.
Cleanliness and good hygiene practices are good general biosecurity tools with which all farmers should engage, and we should encourage and drive these conversations. This includes practicing good hygiene during field-days.
However, risk of transfer of M. bovis by mud, indirectly, is very low. Other risks (milk and animals) are far more important and this needs to be communicated to farmers. We shouldn’t be overly alarmed about muddy tyres, but we should be alarmed about indiscriminate movement of milk and animals.
There’s a good summary of how farmers can protect their herd from infection on the MPI website here (see the document 'Guidance on protecting your farm') .
Pet days present challenges so risks must be managed
With the above in mind, pet days and/or calf days do present some challenge. On first principles, they involve movement of animals and this should be carefully considered prior to engaging in these events. For transmission of disease, M. bovis requires prolonged (undefined) close contact of a susceptible host, with an animal that is shedding.
In all likelihood, in a low-risk area, in a well-managed environment, risk of disease transfer is probably very low. In the hot spots, very careful consideration of whether to proceed with a calf day would be prudent.
If pet days are to go ahead, things to consider are NAIT records, and likely farm risk (prior to any nationwide risk assessment approach coming available), and ensuring calves are not mixed. Close contact should be prevented, avoid sharing milk, and don’t share other equipment (e.g. grooming brushes, halters). Equipment is important in managing other diseases (e.g. ringworm), so personal hygiene including hand-washing should be encouraged.
It’s a balance of the benefits of community spirit and relationships, and the joy that kids get from these events vs. risk of M bovis. We do need to be mindful of the risk – and if in doubt, don’t do it. But community engagement and relaxation is really important right now too. Take care of yourselves.
Read MPI’s fact sheet on pet days and other rural events here (see information under 'Calf day, cattle shows and events')