Caught between validation of results and the case definition

A highly sensitive and timely detection system is the cornerstone of an effective response to either incursions of exotic diseases and pests or the emergence of new organisms. The trade-off is a reduction in system specificity. This presentation describes a number of investigations and responses involving MAFBNZ Investigation and Diagnostic Centre which were the result of specificity issues (false positive results). How and why did false positives occur, why are they important, the IDC approach to investigation of false positives and how this differs to traditional outbreak investigation together with some a priori decisions to reduce the impact of false positive results are explored.