General guidelines for statistically sound and risk‐based surveys of plant pests

Abstract

At the request of the European Commission, EFSA prepared the general guidelines for surveys of plant pests, describing the legal, international and scientific context in which the surveys are designed, the basic principles implemented for surveillance of quarantine pests and introducing the concepts needed for the design of statistically sound and risk-based surveys. Three types of specific surveys are addressed: detection surveys for substantiation of pest freedom, delimiting surveys for determining the boundaries of an infested zone, and monitoring surveys for prevalence estimation when measuring the progress of eradication measures or for confirming a low pest prevalence area. For each survey, the survey parameters are introduced and their interactions analysed showing the importance of the assumptions that are taken for each one of them: (i) the aims of the survey are defined as the confidence of detecting a given pest prevalence (design prevalence), this reflects the trade-off between the acceptable level of the risk and availability of resources that determine the strength of the evidence to support the conclusion of the survey; (ii) the target population is addressed in terms of its structure and size, including the risk factors; and (iii) the method sensitivity is defined as the combination of the sampling effectiveness and the diagnostic sensitivity. EFSA's RiBESS+ tool is introduced for calculating the sample size using the survey parameters as input values for a statistically sound and risk-based survey design. The mathematical principles behind the tool are in line with the International Standards for Phytosanitary Measures. The survey design is flexible and can be tailored to each pest and specific situation in the Member States. Once the survey is implemented following this approach, the conclusions allow surveys to be compared across time and space, contributing to the harmonisation of surveillance activities across the EU Member States.

Pest survey card on Citrus leprosis viruses

“…Figure 2 shows the next steps after the survey preparation for designing statistically sound and riskbased detection and delimiting surveys of citrus leprosis viruses. Guidance on the selection of type of survey, related survey preparation and design, is provided in the EFSA general guidelines for pest surveys 1 .…”

Surveillance for Early Detection of High-Consequence Pests and Pathogens

“…This is commonly achieved by using statistical models to identify epidemiological "strata" within a population and quantify their relative risk of infection (Doherr & Audigé, 2001;Hadorn & Stärk, 2008;Martin et al, 2007). Approaches based upon methods such as this have been used to plan surveys to declare the absence of pests and pathogens of both animals (Calistri et al, 2018;EFSA, 2012) and plants (Lázaro et al, 2020).…”

Pest survey card on Erwinia amylovora

“…Figures 2 shows the next steps after the survey preparation for designing statistically sound and riskbased detection and delimiting surveys of E. amylovora. Guidance on the selection of type of survey, related survey preparation and design, is provided in the EFSA general guidelines for pest surveys 1 .…”

“…Steps required for the preparation, design and implementation of detection and delimiting surveys, in accordance with the methodology for statistically sound and risk-based surveillance 1…”