Anthony Duignan
Department of Agriculture, Food and the Marine
Ireland
Title: The role of tuberculin assays on naturally infected cattle in the Irish eradication program
Biography
Biography: Anthony Duignan
Abstract
The Irish Bovine Tuberculosis (bTB) eradication program includes annual Single Intra-dermal Comparative Tuberculin Test (SICTT) screening of all herds. The SICTT is conducted by comparing the separate cell-mediated immune responses to an intra-dermal injection of avian and bovine PPD tuberculins in each animal. Tuberculin PPD standardization is necessary in order to ensure sufficient diagnostic strength for eradication and also to guarantee animal status for international trade. The potency of a tuberculin is estimated by comparing the size of the reactions elicited by an intra-dermal inoculation to the size of the reactions of a ‘standard’ tuberculin of known potency. OIE recommends that tuberculins are assayed in the population of animals in which the eradication program is to be carried out but due to practical difficulties in performing potency assays in cattle they are usually assayed in guinea pigs. However, ever since inadvertently using sub-potent tuberculin many years ago the routine assay of tuberculins in naturally infected cattle is regarded as imperative to the assurance of potency of tuberculins used in the Irish bovine tuberculosis eradication program. The purpose of this presentation is to give an account of the procedures and outline the role of assays carried out on naturally infected cattle in the quality control on the Irish Bovine Eradication Program. Ireland is perhaps unique in that it is one of the few if not the only country conducting routine tuberculin assay in naturally infected bovines as part of the quality control of the national bTB eradication program.