Prioritization of Microbial Research Needs for Fresh Produce in Canada

On March 19, 2008, the Bureau of Microbial Hazards (BMH), Health Canada hosted a working group meeting to prioritize microbiological research needs for fresh produce in Canada. The group reviewed the list of priority produce/pathogen combinations which had been developed by an expert FAO-WHO working group (Microbiological hazards in fresh fruits and vegetables, Expert Meeting Report, October 2007), and adapted the list to the Canadian context. The working group created the "Top 10" list of research needs and ranked all identified research topics into three categories (high, medium and low priority). The purpose of this document is to provide research institutions and other interested parties in Canada with the list of prioritized research needs.

Validating criteria for prioritization process

The following criteria were developed by an expert FAO-WHO working group (Microbiological hazards in fresh fruits and vegetables, Expert Meeting Report, October, 2007) and adapted to the Canadian context:

Prioritization Exercise

Using the criteria above, all identified research needs were placed into three categories, i.e., high (H), medium (M) or low (L).

Top 10 Research Needs:

    1. Under what conditions can fertilizers derived from human/animal waste be safely employed for the production of produce (under temperate climate with a long winter)?
    2. What is the frequency and amount of pathogens introduced into the environment by use of manure-contaminated soil amendments and fertilizers?
    3. Efficacy of ageing/composting (taking into consideration our winter conditions): What is the survival rate of pathogens contained in fresh manure? Is there a need to establish the time of application (time-interval to wait before harvest)? What is potential for re-growth of pathogens?
    4. What are the factors affecting pathogen environmental loading and survival?
      • Adequacy of and compliance with composting procedures
      • Manure application scheduling during various phases of the growing cycle
      • Does the risk decrease if manure is applied to fields in the fall?
      • Can winter be considered a kill step for those pathogens?
      • Influence of timing and method of application on the survival of human pathogens from raw manure in different soils, under different climates
    1. How does irrigation water become contaminated?
    2. What influences the survival of pathogens in irrigation, ground, well, and surface water?
    3. What is the frequency and amount of pathogens introduced into the environment by water sources prior to and during various phases of the growing and harvest cycle?
    4. Does weather/time of the year play a role in pathogen survival in water and soil? (Contamination according to season)
    1. What is the evidence of internalization of pathogens into produce and how significant is this?
      • Is it a problem with crops other than tomatoes, apples and potatoes?
      • What are the best prevention methods?
      • Once pathogens infiltrate the product, how long will they survive/grow?
      • Can epidemiologically relevant numbers of pathogenic microorganisms infect a field crop via this route?
    2. Internalization
      • Pre-harvest: What is the risk of pathogen uptake by growing plants (leafy greens, tomatoes, fruits)
      • Post-harvest: Influence of processing parameters and how can one eliminate pathogens.
  1. What is the effectiveness of hand sanitizers and gloves on farms? (i.e., in the field, packaging house, re-packer and whole-sale level)
    • Effectiveness of hand sanitizers when hands are not washed first washed free of dirt/plant debris.
    • Effectiveness of hand wipes
    1. What is a better way of maintaining the conditions of flume water and rinsing water at packing establishments? Research to identify where pathogens are being introduced.
    2. What is the effectiveness of cleaning water in terms of reducing pathogen loads on produce?
      • Does water remove pathogens from product?
      • How much pressure needs to be applied?
      • How long does the product need to be in contact with the water?
      • How often should water be changed?
    1. Development of sampling protocols to facilitate efficient and reliable detection of pathogens?
    2. Sampling field crops: what, where, when, how much?
    3. Development of methods (fast and sensitive) for improving the timely detection of pathogens (bacteria, viruses, parasites) in or on fresh produce?
    4. Improvement of sample preparation (surface samplings vs low pH of mash, enrichment, background flora)?
    1. Research on interactions between pathogens, processed/stored plant tissue and the competitive microflorae.
    2. Research on survival and potential growth of pathogens on produce during the post-harvest process (handling, processing and/or distribution)
  2. What is the behaviour (survival/growth) of pathogens in fresh-cut produce from time of packaging to consumers?
  3. How many people are actually becoming sick from fresh fruits and vegetables in Canada?
    1. What are the specific foods?
    2. Where do they come from?
  4. Factors influencing attachment of pathogens to produce; why are some pathogens associated only with specific produce (i.e., tomatoes are associated with Salmonella, but not with E. coli. What intervention strategies could be developed?)

Overarching research question:

What is the mechanism of transference of human pathogens to fresh produce edible plant surfaces during growing, harvest post-harvest handling, processing and distribution operations,andwhat factors affect transference?

High Priority Research Needs (Not in the Top 10):

Medium Priority Research Needs:

Low Priority Research Needs:

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2017-05-04