PM 7/76 (6) Use of EPPO Diagnostic Standards

Abstract

This Standard describes the purpose and use of EPPO Diagnostic Standards. Definitions used in these Standards are given in Appendix 1. This Standard is based on ISPM 27 (IPPC, 2006).

Approved in 2006-09. Revised in 2010-09, 2014-09, 2016-11, 2018-09 and in 2024-09.

This Standard is designed to be used in conjunction with the EPPO Standards of series PM 7 on diagnostics.

Diagnostic tests have different performance characteristics (e.g. levels of analytical sensitivity and analytical specificity resulting in different risks of false-positive and false-negative results), speed and cost. These elements are taken into account by the customer and the laboratory when choosing a test or a combination of tests for the diagnosis of a pest in specific circumstances of use.

The reliability of a test depends on its performance characteristics, obtained from validation and verification studies. Information on how to perform validation and verification is provided in PM 7/98 Specific requirements for laboratories preparing accreditation for a plant pest diagnostic activity (EPPO, 2021). Validation data is not available for all tests that are currently widely used in plant pest diagnostic laboratories. Lack of validation data is, in particular, often the case for routine tests such as ELISA or morphological analyses. However, there is often a long period of experience of use of such tests and it is usually possible for the laboratory to qualify the reliability of such tests (e.g. based on the number of years of experience, the number of samples tested, the use of controls and participation in proficiency tests). It is nevertheless recognized that performance characteristics allow a better understanding of the reliability of the tests. There are cases where a combination of tests is used to increase the overall accuracy and confidence in the diagnosis (e.g. see Section 4).

It should be noted that the result of a test or a combination of tests also depends on the proficiency of the laboratory.

Critical cases:

The circumstances of use described in the latter three bullet points (in bold) are considered in this Standard as critical cases where additional confidence in the outcome of the diagnosis will be required (see Section 2.1). The detection of a pest in a consignment declared to have been submitted to a phytosanitary treatment is also considered to be a critical case (see also Section 5.3.2).