Over the past month or so, the Anexa FVC team have been fielding an increasing number of inquiries around testing for Mycoplasma bovis. This increase no doubt reflects the discovery of M.bovis in, now, two dairy herds in the Waikato.
There are two types of tests that have been developed for detection of this infection in cattle. The first is a PCR test which attempts to identify the presence of the M. bovisbacteria by the DNA of the bacteria. The second test type is an ELISA which looks for the presence of an antibody response to the bacteria in an infected animal. They work in fundamentally different ways. The PCR is generally used on whole milk or nasal secretions, while the ELISA is a blood test typically. Neither test is perfect at identifying infection – in fact, they are tests with only average performance and this is due to the nature of the infection. Mycoplasma bovis is very good at establishing a subclinical infection with a low level immune response making detection with both tests challenging.
Testing for M. bovis has now become available at commercial labs other than those run by MPI. If a sample returns a positive test, the commercial lab is obligated to forward the results and sample onto MPI as is standard for an exotic disease organism. If you are contemplating testing animals for M. bovis (eg testing introduced herd bulls) it is important that you contact your Anexa FVC veterinarian for further advice on the number of animals required for testing and what this means for interpreting any results. It may also be a timely opportunity to conduct a Biosecurity Risk Assessment with your herd vet. This process takes around an hour and is highly useful at identifying risk factors for multiple diseases we are wishing to minimise or prevent.