Mycoplasma bovis

Jersey cows

Mycoplasma bovis

The New Zealand Veterinary Association (NZVA) is supporting veterinarians to help farmers respond to the detection, and eradication of Mycoplasma bovis in New Zealand.

Here you will find:

If you have any concerns about your animals, contact your veterinarian as soon as possible for advice or call the Ministry for Primary Industries on 0800 80 99 66.

For the latest updates on Mycoplasma bovis and infected properties you can visit the MPI website and subscribe to the weekly MPI Mycoplasma bovis stakeholder update.

Frequently asked questions

Mycoplasma bovis (M. bovis) is a bacterium which infects cattle, and may have several clinical manifestations including mastitis, abortion, pneumonia and arthritis. It provides a negligible risk to humans (except in extraordinary circumstances) and presents no food safety risk in commercial-grade food products. Any unpasteurised milk products should be approached with caution, especially for children, the elderly and immunocompromised individuals (this is not specific to M. bovis).

Infected animals may not show any signs of disease - infection can be latent, or entirely sub-clinical. In times of stress (for example, calving, drying-off, transporting, or being exposed to extreme weather) infected cattle may shed bacteria from any mucous membrane and in bodily secretions (e.g. nasal, milk, semen).

The disease is found worldwide, and is not considered a disease of relevance to trade by the World Animal Health Organisation (the OIE). There are no restrictions for meat and dairy product trade due to M. bovis.

    Internationally, the disease is managed by farmers through:

  • Good biosecurity practices on their farms
  • Careful selection of replacement stock and breeding bulls
  • Keeping herds in a good health and minimising stress
  • Rigorous management of clinical cases

This is the first time M. bovis has been found in New Zealand, and it is an Unwanted Organism under the Biosecurity Act 1993.

Since M. bovis was discovered in mid-2017, infected and high risk properties have been place under legal controls, and extensive national surveillance undertaken to determine the distribution of the disease in New Zealand. In May 2018, the New Zealand Government announced it was undertaking a phased eradication approach to eradicate the disease from New Zealand. More information on the eradication decision can be found on the MPI website, and in this cabinet paper.

So far, the most common presenting signs of M. bovis infection in New Zealand cattle have been clinical mastitis (with poor response to treatment), and arthritis. However, other clinical presentations may include pneumonia, otitis media, late-term abortion, and conjunctivitis. Latency and sub-clinical disease are two of the most challenging problems with M. bovis.

Latency means that even though the cattle do not currently have clinical (or subclinical disease) they may still be carrying the bacteria (e.g. in tonsillar crypts), and may subsequently recrudesce to clinical or sub-clinical disease at times of stress.

During active infection, cattle may be entirely sub-clinical– they may be shedding and bacteraemic, but appear completely healthy; or they may have clinically evident disease - this can be triggered by increased stress such as calving and milking.

More information is available on the MPI website.

The greatest risk for spread of M. bovis is movement of infected cattle. Infection is transmitted between cattle that are in close contact - generally prolonged or repeated contact with infected animals is required.

Feeding of infected raw milk to calves is also a known risk factor, and is one of the two highest risks factors for spread.

M. bovis may also be spread on equipment used between farms. Because milk may contain M. bovis, milking equipment is particularly important to clean and disinfect if the equipment is shared between properties or herds.

Contaminated mud or faeces from infected animals also has the potential to spread disease, however it is a much lower risk. Given the bacteria is fragile outside of its host, cleaning and disinfection, and ultraviolet light all render the bacteria non-infective reasonably easily.

Remember most disinfectants do not function in the presence of organic matter – cleaning is required prior to disinfection, and replenishing disinfection solutions contaminated with organic matter is required to ensure efficacy. Contact time is also critical for efficacy.

Transmission of disease by running different lines of stock through yards and races is extremely unlikely, unless bodily secretions remain in significant amounts, and contain an infective dose that then contacts a susceptible animal’s mucosa. Although it is very rare for M. bovis to infect animals other than cattle (and America bison), other animals may carry the bacteria and in theory could pass this on to a susceptible cattle beast. The significance of this is unknown as a route of disease transfer. Where possible, it is prudent to keep infected cattle isolated from all other species.

M. bovis does not survive in soil for a long period. Properly made silage with a pH < 4.5 that is wrapped correctly, is not considered a significant risk for transmission of Mycoplasma bovis. Silage can be tested to ensure it has reached this standard.

For adult cattle, spread through feed is not a significant risk. Feeding calves unpasteurised milk infected with M. bovis is a cause of spread in countries where this disease is established.

MPI has been tracing all properties which are connected to known infected properties through animal movements. These traces are identified through NAIT records, and farmer records. Trace properties are then contacted, and assessed for their risk of infection. If the risk is deemed low (e.g. all animals present at the time of the trace movement have already gone for slaughter) the property is removed from the trace list. If the risk of infection is deemed higher, the property will be scheduled for surveillance testing.

Further information is available on the MPI website.

Most properties scheduled for testing by MPI will undergo 2 rounds of tests:

Round 1: 100+ blood samples, plus 20 swab samples, and possibly a bulk milk sample.

Round 2: Performed 3-4 weeks after the first round, another 100+ blood samples.

Occasionally further testing may be required if the results seem unclear after the first 2 rounds of testing.

Blood samples are tested with an ELISA test – consecutive samples are required to check for sero-conversion (the presence of antibody). ELISA results are difficult to interpret, and are not appropriate for use on individual animals or small groups. This test is not commercially available.

Swab samples and milk samples are tested with PCR for Mycoplasma bovis DNA. PCR can also be used to test joint fluid and semen. PCR is very accurate, but requires the animal to be shedding from the swabbed surface. Given the tendency for M. bovis to be latent, this makes interpretation of negative results difficult. PCR testing is available commercially, however the NZVA does not support the use of commercial testing in individual animals. See our position statement on commercial testing here.

Further information is available on the MPI website. The NZVA website also has documents detailing how to perform the nasopharyngeal swab technique, and the preputial swab technique.

Spring bulk testing protocol - testing for 2018/19 season

During the 2018/19 season, as part of the M. bovis response, all dairy companies undertook spring bulk milk testing from every farm supplying milk.

This bulk milk surveillance programme was intended to give further assurance of previous non-detects, and identify any clusters of the disease that may have gone undetected in previous surveillance testing.

M. bovis can hide in an infected cow, not showing up until weeks or months after the animal has contracted the disease. The spring months are the best time to test for M. bovis because infected animals are more likely to shed the bacteria after a stressful period, such as calving and the start of lactation.

The Ministry for Primary Industries has provided this Spring Surveillance Programme Specifications information.

Further information is available on the MPI website.

There are three types of legal notices (with movement controls) which may be referred to:

Infected property (IP): A property with confirmed M. bovis infection. These properties will be under a Restricted Place Notice.

Restricted Place Notice (RP): These are issued to properties which may or may not have confirmed M. bovis infection, but are considered very high risk. All cattle movements are prohibited on or off the property, except with a permit issued directly from MPI. Equipment and personal entering or leaving the farm must follow strict cleaning and disinfection protocols overseen by AsureQuality.

Notice of Direction (NoD): These are issued to properties which have an unknown level of risk – such as trace farms which have not yet been tested, or have results pending. Movements onto the property are not restricted, but any cattle movements off the property are prohibited except with a permit issued directly from MPI. Some cleaning and disinfection processes are likely to be required.

More information is available on the MPI website.

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 what their on-farm risk behaviours and practices.

An online tool for assessment of M. bovis risk (the Dairy Risk Assessment tool, developed by XLVets) has been distributed by the NZVA. This tool is designed for use by veterinarians in consultation with their dairy farming clients, and generates a risk 'score' based on farm management practices known to be a risk for spread of M. bovis. Veterinarians are then able to give specific advice to help farmers reduce their risk. Find out more on our website at

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.

Key points for discussion on minimising risk

Animal movements

Farmers should limit cattle movements onto their farms and avoid their animals coming into contact with their neighbours’ animals. Double-fencing all boundaries and ensuring they are stock-proof, is a sensible pre-caution. Accurate NAIT is required, and animal movement history should be considered before new stock is introduced. See above for more information.

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. This is key to reducing transmission of M. bovis because milk movement is not currently recorded in New Zealand, and therefore presents a real challenge in the response tracing. If milk is transported between farms, NZVA strongly recommends that movement between farms is always linked to calf movement between the same farms– in other words, 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 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).


Transportation of infected cattle remains the greatest risk of disease spread, but the contaminated trucks are also present a small risk regarding spread of disease. Disinfection is only effective in the absence of organic matter. Therefore reducing risk is a two-step process – first thorough cleaning, then disinfection.

The most important thing to do is hose all the mud, faeces and urine out of the trucks and let all surfaces dry. Sunlight and desiccation destroy Mycoplasmas, so with good cleaning, drying and then disinfection there is little chance Mycoplasma bacteria will survive. Ideally, trucks should be thoroughly cleaned between loads from different farms, particularly those under legal notice. It is not necessary to clean between loads from the same farm. Trucks should be cleaned and disinfected at the end of the day.

What this will mean in practice is multiple consignments on one truck should to be avoided.

Farmers should be instructed to minimise the number of trucks used to cart stock, For example, using one truck all day for one property rather than 5 trucks over a couple of hours, and then going to the next farm. This limits the C&D required and minimises costs for the trucking company. Trucks should then clean and disinfect before the next property.

Pet days

With the above in mind, calf days do present some challenge – on first principles, they involve movement of animals and this should be carefully considered prior to being undertaken. For transmission of disease, M. bovis requires prolonged (undefined), close contact of a susceptible host, with an animal that is shedding.

If pet days are to go ahead, and include calves, things to consider are NAIT records, and likely farm risk, ensuring animals are not mixed, preventing close contact, avoiding sharing of milk and other equipment (e.g. grooming brushes, halters). Fomites are important when considering other diseases (e.g. ringworm), so personal hygiene, including hand washing and not sharing equipment, should be encouraged.

In all likelihood, in a low-risk area, in a well-managed environment, risk of disease transfer at a pet day is probably very low. In the hot spots, careful consideration would be prudent. During the current eradication phase, NZVA advocates calves are not taken to pet days.

Muddy tracks and trucks

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 veterinarians should encourage and drive these conversations.

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.

We have recently created an NZVA Mycoplasma bovis Group (NZVA MbG) which we hope will operate in a similar manner to the existing BVD Steering Committee. Primary objectives will be to represent the profession to inform and advocate for the long-term outcomes desired by veterinarians. The NZVA MbG will develop resources and guidance documents for members and the public, and engage with other stakeholders involved in the response (such as MPI).

The NZVA invites feedback and participation from members –this is one of the principle ways we ensure we are accurately representing the views of our members.


Technical information for veterinarians

Mycoplasma bovis - Ministry for Primary Industries website
Status reports, guidance for farmers and farming communities, reports and notices issued by MPI.

Biosecurity advice and information

Guidance on protecting farms from Mycoplasma bovis
Guidance and information for farmers.

Best practice biosecurity protocols
Advice from the NZVA Society of Dairy Cattle Veterinarians and the Sheep and Beef Cattle Vets Branch on biosecurity measures that should be taken to minimise the risk of the introduction of Mycoplasma bovis on farms.

Biosecurity response to Mycoplasma bovis - MPI Mycoplasma bovis intelligence team
Conference proceeding from the 2017 Society of Dairy Cattle Veterinarians.

Standard Operating Procedures and testing information

Standard Operating Procedure for Nasopharyngeal Swab Technique for Cattle

Standard Operating Procedure for Preputial Swab Technique for Bulls

Testing of Service Bulls for Mycoplasma bovis in New Zealand
Advice from the NZVA Society of Dairy Cattle Veterinarians.

Laboratory testing for Mycoplasma bovis in New Zealand – advice for veterinarians

Other articles

Mycoplasma bovis infection on a South Canterbury dairy farm - Merlyn Hay
Conference proceeding from the 2017 Society of Dairy Cattle Veterinarians

Information for farmers and the general public

Visit the MPI website to access useful information and documents for farmers, industry professionals, and members of the general public.

If you have any concerns about your animals, contact your veterinarian as soon as possible for advice or call the Ministry for Primary Industries on 0800 80 99 66.

Communications to members of the NZVA

Video update from NZVA President


In this short video, NZVA President Peter Blaikie explains the NZVA's role in the eradication decision, what NZVA is doing to support members and farmers, and the role of our new M. bovis Steering Group.

July 2019

  • Mycoplasma bovis apology accepted: 5 July 2019
    • The New Zealand Veterinary Association (NZVA) accepts the Government's public apologies for the way the Ministry for Primary Industries (MPI) has handled the programme to eradicate Mycoplasma bovis.

August 2018

  • NZVA update: 1 August 2018
    • Who's who in the M.bovis response?
    • Are calf days on or off?
    • What are NoD, IP and RP and how do they relate to each other?
    • What's the plan for bulk milk testing in spring?
    • Testing, testing, testing - what's the right way?
    • Fitness-for-transport certification

July 2018

  • NZVA update: 20 July 2018
    • Transport of heavily pregnant stock and requests for veterinary certification
    • The NZVA is aware that members are being asked to certify late gestation cows as being fit-for-transport to slaughter premises (and possibly other locations). These cows are, for a variety of reasons, affected by the Mycoplasma bovis incursion (for example, farm or run off under NOD, RP or IP).
    • The NZVA's advice to members is that members should not certify within four weeks of the planned start of calving.

June 2018

  • NZVA update: 29 June 2019
    • Update from the CEO
    • Cabinet paper reveals thinking behind M. bovis decision
    • Who's on NZVA's Mycoplasma bovis Group and what they will do
    • Ensuring lifestyle blocks understand the risks and how to protect themselves
    • Biggest risk factors are animal movement and raw milk
    • Possible move towards closed herds – how M. bovis could change farming permanently
    • Latest information from MPI
  • NZVA update: 15 June 2018
    • Video update from NZVA President
    • Dates for industry/MPI roadshows
    • MPI's M. bovis presentation - useful information to share with farmers
    • Latest MPI fact sheet - more details on testing, source of infection
  • NZVA update: 13 June 2018
    • 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
      • Biggest risk factors are animal movement and raw milk
      • Clean muddy gear and vehicles before you disinfect
      • Pet days present challenges so risks must be managed