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About M. bovis

What is M. bovis?

Mycoplasma bovis (M. bovis) is a bacteria that can cause serious health conditions in cattle, including mastitis (udder infection), pneumonia, arthritis, and ill-thrift in calves. Less commonly it can cause progressive neurological disease in calves, conjunctivitis, and reproductive losses.

The infection is:

  • difficult to diagnose in an individual animal - bacteria can hide from the immune system within the body, making it hard for cattle to fight off infection
  • often untreatable – in the majority of cases antibiotic treatment is unsuccessful, and symptomatic animals are culled.
  • most likely to reveal itself in times of stress - cattle can be infected with M. bovis without showing any signs of disease. During times of stress such as during calving, early lactation, drying-off, transport or exposure to extreme weather conditions, infected cattle are more likely to show signs of infection.

How it spreads

M. bovis typically spreads between cattle when they are in close contact for a prolonged period of time (i.e. when they are together in a paddock, pen, or milking shed). Usually, infection spreads between farms when infected cattle are brought into a previously uninfected herd. Infected animals may ‘shed’ (release) bacteria in milk and/or nasal secretions, enabling the bacteria to spread to other cattle.

M. bovis can also be spread to calves that are fed milk from infected cows. The bacteria may be spread via genetic material containing the bacteria such as semen, but this means of spread is extremely rare compared to spread via the movement of live cattle and milk.

M. bovis is fragile in the environment—it only survives for very short times when exposed to heat, drying and UV light, but can survive longer in cool, moist and dark environments.

Equipment used as part of the milking process has been linked to the spread of infection between cattle on individual farms.

How it does not spread

M. bovis is unlikely to survive in grazing areas and areas used in baleage and silage production. The ensiling process creates an acidic environment (approx. pH 4.5) where M. bovis bacteria are unlikely to survive. Silage and baleage pose an extremely low risk of spreading M. bovis and may be fed as usual or transferred off the farm for sale.

The risk of M. bovis spreading via organic material such as soil, effluent, and other feed types is also extremely low.

No risk to food safety, and international trade

The M. bovis bacterium does not pose a risk to human health and it’s safe to eat meat and drink milk from infected cattle.

It’s not considered a disease of relevance to trade by the World Organisation for Animal Health (WOAH) and internationally, there are no regulatory restrictions for meat and dairy products due to M. bovis. Infection is common in many food producing nations, and where infected cattle aren’t showing signs of infection they are processed for human consumption.

In New Zealand, our laws mean any animals that are very sick, severely injured or have medications in their bodies are not processed for human consumption. All animals are also examined after slaughter to ensure the meat is safe and suitable for consumption.

Clinical signs of M. bovis

You should contact your vet and MPI as soon as possible if:

  • clinical signs consistent with M. bovis appear at higher than normal rates
  • several animals show signs of M. bovis infection
  • individual animals show several signs of M. bovis infection
  • affected animals don’t respond to treatment
  • multiple classes of stock show signs of M. bovis infection (e.g. mastitis in cows and arthritis in calves).