Mycoplasma bovis – update

Background

Mycoplasma bovis is a bacterial disease of cattle. It is found in most countries but has only just been found in NZ. MPI plan to eradicate the disease.

Symptoms

  • unusual mastitis in cattle that doesn't respond to treatment
  • arthritis in cows and calves
  • late-term abortion
  • pneumonia in calves
  • conjunctivitis in calves
  • signs of ear infection in calves - droopy ears, head tilting, discharge from ear

 Testing for m.bovis

There are two tests:

  • elisa - a blood test which shows antibodies
  • PCR - test on milk and swabs which detects the presence of the bacteria

The problem is that m. bovis hides in the immune system and may only be able to be found when the animal is actively shedding. Infected animals tested in a normal pastoral environment may test negative but when stressed - by weather, change of environment, transportation etc they may start showing symptoms and test positive.

This means that multiple tests must be done multiple times over an extended period before a definitive answer is found. Even then it's not always possible to be 100% certain.

Spread

So far the evidence from both here and overseas shows that the most common way in which m. bovis is spread is by prolonged animal contact or calves drinking milk from infected cows. There is no evidence so far of over the fence contagion without substantial animal contact. The spread in NZ has been within herds and via stock movements from one farm to another.

The bacteria does not persist in the soil for long and MPI believe that letting infected properties lie fallow for 60 days after the stock have been culled will prevent the chance of re-infection. Urine and faeces are not regarded as significant vectors but see good practice below.

It is technically possible for Mycoplasma bovis to be transferred to some other animals, including pigs, sheep and goats. However, it is extremely rare because it can only be spread to them by feeding them raw milk from an infected cow. No transmission of the disease back to cattle has ever been recorded. Other hosts are considered to be a dead end infection and are not important in the ongoing spread of disease.

Good practice

Nose to nose contact with your neighbours’ stock should be prevented as Mycoplasma bovis is spread through direct contact between animals. This can be achieved by creating buffer zones using electric outrigger fencing or a separate electric fence two metres back from the boundary.

If you are buying in cattle stock

Make sure the stock are healthy - use MPI's checklist here.

Quarantine stock on arrival for a week to see if they develop symptoms. This is not just m. bovis it's good practice to avoid infecting your farm with other of diseases.

Take sensible biosecurity measures.

Thorough farm hygiene can reduce the risk of the disease entering your farm. Make sure that footwear, protective clothing and equipment that has been in contact with animals on other farms is not used on your farm, or is properly cleaned and disinfected before use.

Second hand equipment that has been in contact with animals, especially bodily fluids, presents a higher risk of transmission and should be cleaned and disinfected prior to use.

Vehicles coming on and off your farm should be confined to the main access track. Use your own vehicles to transport visitors around your farm.

Cleaning and disinfection

This is a two-step process. Disinfectants won’t work through dirt, so it is important to remove all visible dirt and dung from gear and vehicles that have been in contact with stock.

Once items are clean, use a disinfectant. It’s best to leave disinfectant on items for a few minutes – ten minutes is best.

Suitable disinfectants are: 1% Virkon (made by mixing 50gstandard sachet) Virkon with 5 litres water), 0.2% citric acid (made by mixing 1 tsp of citric acid with 1 litre of water), Trigene, or any appropriate disinfectant used to the manufacturer’s instructions.

Provide a foot bath with disinfectant and a scrubbing brush for visitors to clean their boots when they come on and off the properly.

Have clean hot water and soap available so visitors can effectively clean their hands and any equipment that they need to take off farm (e.g. vet’s equipment).

If your livestock show any symptoms of m. bovis then talk to your vet or contact MPI directly.

Finally

Overall - the message is that it should be safe to buy and sell cattle with farms that are not under any form of control. But be sensible.

Make sure all cattle comply with NAIT regulations and register all stock movements on NAIT within 48 hours.

MPI are arranging local meetings around the country - go along and find out more about your local area. The meetings aren't scheduled yet but we'll have the dates and venues on lifestyleblock.co.nz when they're available.

For more information check out MPI mycoplasma bovis.

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