An official website of the United States government.

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

A Systematic Assessment of the Use and Value of Deliberate Challenge Trials in Pre-Harvest Food Safety Research


The overall aim of this study is to formally evaluate the evidence for pre-harvest food safety intervention efficacy provided by challenge studies in the pre-harvest food safety literature. We will address this aim with the following objectives.

<OL> <LI> Evaluate whether estimates of intervention efficacy for specific intervention - pathogen - species combination are the same in challenge studies as in field trials. To provide breadth to this evaluation, the following intervention - pathogen - species combinations will be included: bacteriocins, vaccines and probiotics/competitive exclusion products for Salmonella in swine and poultry, Campylobacter spp in poultry and VTEC in cattle. Systematic review and meta-analyses will be used to compare intervention estimates between trial types.
<LI>Describe the temporal sequence of challenge trials and field trials within intervention- pathogen-species combinations. If the results of challenge trials are used to inform the need for field trials, they should be conducted first. Descriptive statistics will be used to describe the temporal sequence combinations evaluated under objective 1.

<LI>Evaluate the point in the temporal sequence of challenge trials at which sufficient evidence of intervention efficacy is achieved. Cumulative meta-analysis will be used to assess the cumulative measure of intervention efficacy.

More information

Expected Benefits: <BR>
Findings from this study will enable researchers to be more efficient in testing of pre-harvest interventions by indicating where challenge trials are appropriate, and whether field trials are needed in all instances to confirm the results of challenge trials. Additionally, the results will provide data that policymakers and governmental agencies can use to aid in the determination of funding allocation for future research on pre-harvest interventions and in making recommendations for use of interventions based on current research evidence. Likewise, the findings may be of interest to commodity-group/producer organizations and producers who make decisions on funding pre-harvest intervention research

Sargent, Jan
University of Guelph
Start date
End date
Project number