29 Aug Tuberculin potency

You may have noted a recent update from the APHA in regard to ordering new stocks of tuberculin. From mid-July all orders must be directed to Weybridge via the email address [email protected].

On a scientific note you may be interested to learn that after recent discussion with experts in the production of tuberculin we have learned more about why it is always advised to take care regarding the batch number and the lot numbers of tuberculin used during TB testing.
As well as the batch numbers on avian and bovine vials there is also a lot number that applies to batches of both
avian and bovine tuberculin. Ideally only avian and bovine vials of the same lot number should be used on the same skin test. The OV instructions for the storage and use of tuberculin currently make reference to the “kit batch number” and say that an OV should not mix different sizes of vials or different kit batch numbers at the same test. There is an allowable range of tuberculin potency in the production and release process. Because different batches of avian and bovine vary a little in their potency, batches are then carefully ‘matched’ within lots before dispatch. This is to ensure that a low potency avian tuberculin is not used as comparator for a high potency bovine tuberculin or vice versa. If this were to occur then the sensitivity of the test may be affected.