Re: Reactors at TB tracing tests

Vikki Halliday LLB — Wed, 27 Jan 2010 22:05:43 GMT

I response to your query I used to be a VO for DEFRA, and yes we do find reactors at tracings, however usually they are uncovered fairly quickly by the full time staff who tend to carry out the high risk tracings as a priority. I once ended up having to slaughter out a whole beef farm after he bought one animal from a herd subsequently confirmed with TB, and have had to slaughter several in-contacts at tracings carried out from farms with very low levels of TB in the tests.

The farm in question that I ended up completely slaughtering was one animal which had been tied up in a byre over the winter, immediately adjacent to a confirmed case at slaughter, this animal was bought at the back end of the year as an in calf animal and ended up running in a shed with the remainder of the spring calvers, hence the 40% reaction at the first tracing test.

I guess therefore it depends on the acual contact and epidemiological history of the animals as to whether you would find reactors, but they are a valuable safety net as they do tend to find the potential problems as soon as possible.

Vikki