The Mycoplasma bovis Programme, in consultation with industry, has decided to continue screening bulk tank milk, with a few modifications to the regime that will improve our ability to identify infected farms and support the eradication of Mycoplasma bovis (M. bovis).
National screening will be conducted monthly, kicking off on 1 July, and will continue indefinitely.
The Spring Surveillance Programme proved extremely valuable as it provided assurance that infection is not widespread outside already identified farms. It also identified a small, additional number of infected farms not found through animal movement tracing, as well as highlighting the ability of the ELISA test to produce a very low rate of false positive results.
Ongoing screening of bulk tank milk samples nationally may identify infected herds otherwise undetected due to incomplete and inaccurate movement records, and may identify infected herds faster than the tracing of animal movements, as those movements can only be traced once the source Confirmed Property is found.
A summary of what's changing:
- Going forward only the ELISA testing method will be used – it has proven to be a much better screening tool than the PCR test.
- Farmers will be notified of all ELISA-positive test results within 2 weeks of testing.
- Farms with an ELISA-positive test result will be placed under a Notice of Direction (a NOD) restricting cattle movements (a NOD) while sampling and testing of the herd is carried out to determine the disease status of the farm.
- ELISA-negative test results will be regularly reported to farmers. The programme is working with industry to explore automated ways to report negative results. An update on the format and frequency of this reporting will be provided before July 2019.
It is important to emphasise that bulk tank milk ELISA-negative test results do not prove absence of infection, nor does a positive test result prove that a herd is infected. It is an indication only, and further testing needs to be carried out.
"Unfortunately, there isn't a single 'yes or no' bulk tank milk test for M. bovis, so it's important that we continue regular screening for at least the next 12 months," says Geoff Gwyn, director of the M. bovis Programme.
"The true M. bovis infection status can only be determined by on-farm testing of the herd."
Previously the programme has not used the bulk tank milk ELISA to screen autumn calving herds in early lactation. Testing this milk is a valuable opportunity to possibly identify additional infected herds prior to the 2019-2020 milking season. Bulk tank milk samples have been stored fortnightly since 15 April 2019, and testing of these stored samples is now underway.
