4.2.2. Bulk Tank Milk Monitoring

In The Netherlands, a C. burnetii monitoring program based on BTM testing is in place to monitor and control infections. A complete description of this program can be found in van den Brom et al. [42]. This program started in October 2009, and until July 2017, BTM samples from all dairy sheep and dairy goat farms were tested twice a month using a PCR. After that, the frequency for PCR-negative farms was reduced outside the lambing season, from July up to November, to once a month, and later to once a month year round. Twice a year, in spring and in autumn, BTM was also tested for the presence of antibodies, using an indirect ELISA, and since July 2017, this has been reduced to once a year in autumn. ELISA results are evaluated in relation to the compulsory vaccination, which must be performed annually within a year after the last vaccination, and for lambs and kids, before the start of the breeding season.