Dairy farmers should be on the alert for a virulent infection that can spread rapidly through herds and be difficult to treat.
Mycoplasma was an emerging cause of untreatable mastitis that had caused significant problems in Australian dairy herds since 2006, Sydney University Associate Professor John House told a Gardiner Foundation presentation in Melbourne on Thursday.
If an outbreak was not identified quickly, it could spread through large numbers of animals and be costly, he said.
One large farm estimated an outbreak cost it $1 million.
The disease could infect both calves and cows and caused pneumonia, tendinitis, middle-ear infection and endometriosis and was potentially fatal.
No treatment was available for milking cows, which had to be culled.
Mycoplasma bovis was also shed in milk, so milk from the hospital herd could not be fed to calves or they could all end up with the disease.
Assoc Prof House said the prevalence of the disease in Australian herds was relatively low – about 3.5 per cent – but it was spreading, and once a herd was infected, it remained infected at a subclinical level.
But numerous farms that had gone through a severe outbreak of the disease were now able to manage it.
The key was being vigilant and acting quickly to isolate any animal suspected of having the disease.
It was also important, particularly on large farms, to have ‘herd memory’, so that new staff were aware of what had happened in the past and could recognise symptoms of the disease if it flared again.
A relatively cheap PCR (polymerase chain reaction) test was now available to detect the disease.
Assoc Prof House said he first became aware of the presence of Mycoplasma bovis in Australian herds in 2006 when he had a request from a dairy farm manager of a herd he regularly treated for a stronger antibiotic to treat cows with mastitis.
The number of cows with mastitis had increased from about 15 to 60 in less than two weeks and most cows were infected in three or four quarters.
The realisation that this disease was present in Australia and that there was no cost-effective test prompted Assoc Prof House to contact Dairy Australia and led to the funding of a project by the Gardiner Foundation to examine the Incidence of Mycoplasma bovis in eastern Australian dairy herds and to develop the relatively cheap test for the disease.
This initial research effort continued with support from Dairy Australia, and has also led to the development of industry biosecurity recommendations to curb the spread of the disease.