International standards for test methods and reference sera for diagnostic tests for antibody detection.

International standards are necessary to ensure that the diagnostic tests used by trading partners meet a minimum standard of diagnostic performance. The tests that are used to qualify animals for international movement must provide a degree of confidence that those animals which give negative test results (and therefore qualify for movement) are free of a particular infectious disease agent. Without the development of standards for diagnostic tests, no level of international harmonisation can ever be achieved. International standards for both test methods and sera serve to establish a baseline on which inferences can be made with respect to the diagnostic performance of a given test in a given laboratory. International standard test methods set baseline analytical and diagnostic performance requirements for new reagents or methodologies. International standard sera are primary reference standards and serve as both reference materials for the calibration of test methods and reagents and prototypes for the production of national and working standards. For most serological test methods, three standard sera should be established: a strong positive, a weak positive and a negative standard. These standards are used to calibrate the detection range and analytical sensitivity of the test method. Assays calibrated in this way are more likely to exhibit a diagnostic sensitivity and specificity which parallels that of the standard test method, thus resulting in a higher degree of international harmonisation.