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U.S. Department of Health and Human Services

Food

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Gaps in the Knowledge Base

Listed here are topics requiring further research, as identified by risk assessments and risk profiles conducted by FDA or in collaboration with other Federal agencies.  Readers who are able to undertake research on any of the topics below, through their organizations' funding sources, are asked to notify the FDA, via the Risk Assessment Coordination Team, of the FDA Center for Food Safety and Applied Nutrition. FDA is not able to provide funding for extramural research on these topics at this time, but readers may wish to explore funding possibilities via the U.S. Department of Agriculture's National Institute of Food and Agriculture (formerly the Cooperative State Research, Education, and Extension Service), at http://www.csrees.usda.gov/.

Note: the following page is under development; more topics will be added.


 

http://www.regulations.gov/#!documentDetail;D=FDA-2011-N-0731-0001.)

Epidemiology of Norovirus Illness
  • Patterns of transmission of norovirus in different settings, such as in a community, a nursing facility, or a household;
  • Proportion of norovirus illness due to person-to-person transmission, food consumption, and bivalve molluscan shellfish consumption;
  • Proportion and determinants of individual resistance to norovirus infection;
  • Underreporting rate for norovirus illnesses arising from consumption of norovirus-contaminated food in United States or Canada;
  • Models describing the transmission of norovirus in a population.
     
Preventive Practices and Controls and Other Factors Influencing Bivalve Molluscan Shellfish Contamination Levels
  • Prevalence of different types of treatment in municipal wastewater treatment (WWT) facilities in the United States and Canada, their relative size (population served), and their location relative to bivalve molluscan shellfish growing/harvest areas. Data submitted should also include information about treatment process(es) (e.g., sequence,timing, and/or concentration of bacteria/viral reducing agent) and effluent flow (volumerates of flow observed in the facility and the  factors that influence the rate);
  • Norovirus or enteric viral surrogate loads in raw wastewater and treated effluent from municipal WWT facilities as a function of type of treatment, water temperature, and season. Data should include the date and time of the measurement, volume rate of flow, weather, size of the community served, and the presence of norovirus outbreaks in the population at the time of measurement (if known). FDA specifically requests comparisons of norovirus or enteric viral surrogate loads in raw wastewater and WWT effluent obtained during the same time period and from the same facility;
  • Experimental data and models describing dilution of WWT effluent in the estuary (e.g., water exchange rate and tidal flush volume) for a representative estuary or estuaries in general. Information should include details on calculations used within the model;
  • Experimental data and models describing norovirus or enteric viral surrogate loss processes that may occur in an estuary, including inactivation by ultraviolet radiation or sunlight, association with particulate followed by sedimentation, and predation by marine organisms. Data submitted should include experimental conditions and ranges (e.g., water temperature, water salinity, season, and estuary water exchange rate);
  • Concentration of norovirus or enteric viral surrogates in sediments, events that cause re-suspension of sediment, and data describing the relationship between nearby sediment and the concentration of norovirus or enteric viral surrogates in bivalve molluscan shellfish. Data submitted should include information about the sediment sampled (e.g., depth, temperature, water salinity, season) and shellfish sampled (e.g., nutrient availability, growth substrate, water temperature, water salinity, season, species, and animal variance), if applicable;
  • Characteristics of sites where stratification of WWT effluent discharge in the water column occurs (e.g., temperature, salinity, depth, surface winds, storm activity, local hydrodynamics, and outfall design) and the impact of these characteristics on norovirus or enteric viral surrogate concentrations in bivalve molluscan shellfish growing/harvest areas (e.g., plume movement and mixing);
  • Norovirus or enteric viral surrogate loads from marine vessel discharge, combined sewer overflow, or other sporadic events that might contaminate bivalve molluscan shellfish growing/harvest areas;
  • Uptake rate of norovirus or enteric viral surrogates by bivalve molluscan shellfish and determinations of the bioaccumulation factor (BAF). Data and information should include a description of the impacts of pathogen particle association, concentration of the pathogen in the water surrounding the bivalve molluscan shellfish, nutrient availability, growth substrate, water temperature, water salinity, season, species, and animal variance on this rate and the BAF. Data submitted should specify the experimental conditions during which uptake was measured (e.g., batch feeding, flow-through feeding, or natural environmental conditions);
  • Inactivation rate of norovirus or enteric viral surrogates within bivalve molluscan shellfish, including the impacts of nutrient availability, growth substrate, water temperature, water salinity, season, species, and animal variance on this rate. Data submitted should specify the experimental conditions during which inactivation was measured (e.g., batch, flow-through, or natural environmental conditions);
  • Elimination rate of norovirus or enteric viral surrogates from bivalve molluscan shellfish including the impacts of nutrient availability, growth substrate, water temperature, water salinity, season, species, and animal variance on this rate. Data submitted should specify the experimental conditions during which elimination was measured (e.g., batch, flow-through, or natural environmental conditions);
  • Models that specifically address uptake, inactivation and elimination of norovirus or enteric viral surrogates by bivalve molluscan shellfish.
     
Post-Harvest Preventive Practice and Controls and Other Factors Influencing Bivalve Molluscan Shellfish Contamination Levels
  • Regional and seasonal landings of bivalve molluscan shellfish species in the United States and Canada;
  • Prevalence and concentration of norovirus or enteric viral surrogates in bivalve molluscan shellfish at the time of harvest, classified by species, location, and seasonal landing;
  • Proportion of bivalve molluscan shellfish, by species, that undergo wet storage, relaying and depuration and the conditions (e.g., times and temperatures) of these practices as applied by the shellfish industry. Data are also requested to determine whether shellfish undergoing these different treatments preferentially serve different postmarkets (e.g., raw/cooked);
  • Experimental data and models that describe the impact of wet storage, relaying, and depuration on the concentration of norovirus or enteric viral surrogate in bivalve molluscan shellfish. Data submitted should specify process and experimental conditions including parameter ranges (e.g., process time, water temperature, water salinity, nutrient availability, growth substrate, species, and season) as well as animal variance;
  • Proportion of bivalve molluscan shellfish, by species, that undergo high hydrostatic pressure (HHP), mild heat, irradiation, freezing, or other postharvest processes. Data are also requested to determine whether bivalve molluscan shellfish undergoing these different treatments preferentially serve different postmarkets (e.g., raw/cooked);
  • Protocols/conditions and parameter ranges for HHP, mild heat, irradiation, freezing, or other postharvest processes as applied to bivalve molluscan shellfish by the shellfish industry;
  • Experimental data and models that describe the impact of HHP, mild heat, irradiation, freezing, or other post-harvest processes on the concentration of norovirus or enteric viral surrogate in bivalve molluscan shellfish. Data submitted should specify the processing and experimental conditions, parameter ranges (e.g., time, pressure and temperature), species, and animal variance.
     
Preventive Practice and Controls and Other Factors Influencing Bivalve Molluscan Shellfish Contamination Levels During Food Preparation and Bivalve Molluscan Shellfish Consumption Data
  • Proportion of bivalve molluscan shellfish, by species, eaten raw and cooked, including method of cooking (e.g., steaming, frying, or baking);
  • Distribution of bivalve molluscan shellfish meal sizes, categorized by species, with regard to season, region, and preparation technique;
  • Distribution of temperatures and times associated with cooking methods (e.g., steaming, frying, or baking) for bivalve molluscan shellfish, by species;
  • Experimental data and models describing the impact of food preparation technique on the concentration of norovirus or enteric viral surrogates in bivalve molluscan shellfish, by species. Data submitted should include food preparation and cooking parameters and ranges (e.g., temperature and time);
  • Prevalence distribution of norovirus or enteric viral surrogate in bivalve molluscan shellfish, by species, at the point of consumption as a function of season, region and preparation technique.
     
Relationship Between Norovirus Dose and Adverse Human Health Effects
  • Human or animal studies that describe the relationship between norovirus dose and the probability and severity of human illness;
  • Human norovirus outbreak data that describe the relationship between norovirus dose and the probability and severity of human illness;
  • Epidemiological and mechanistic data identifying/describing different rates of illness or health outcomes for particular populations (e.g., vulnerable/susceptible populations and resistant populations) exposed to norovirus.

    Listed here are topics requiring further research, as identified by risk assessments and risk profiles conducted by FDA or in collaboration with other Federal agencies.  Readers who are able to undertake research on any of the topics below, through their organizations' funding sources, are asked to notify the FDA, via the Risk Assessment Coordination Team, of the FDA Center for Food Safety and Applied Nutrition. FDA is not able to provide funding for extramural research on these topics at this time, but readers may wish to explore funding possibilities via the U.S. Department of Agriculture's National Institute of Food and Agriculture (formerly the Cooperative State Research, Education, and Extension Service), at http://www.csrees.usda.gov/.

    Note: the following page is under development; more topics will be added.
     

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    Research Needed: Pathogens and Filth in Spices

    • What are the typical levels and distribution of Salmonella in raw spices; that is, before any lethality treatment?  Are these strongly dependent on the type of spice?
    • How effective are the lethality treatments, such as irradiation, ethylene oxide, and steam, in reducing the Salmonella level in spice? Which process parameters are most difficult to control (most likely to fail)?
    • What fraction of each spice consumed/used in the U.S. undergoes a lethality treatment before reaching the retail environment?  What fraction of imported spice is subsequently subjected to a lethality treatment (before retail)?
    • What are the most common/likely sites in the primary and secondary spice processing environments for Salmonella growth/survival? How common is contamination in these environments?
    • What is the rate of growth of Salmonella on wet/moist spices at room temperature or typical storage temperatures? Is this rate strongly dependent on the type of spice?
    • What is the decay rate for Salmonella on dry spice? Is this rate strongly dependent on the type of spice?
       

    Research Needed: Listeria monocytogenes in Ready-To-Eat Foods

    • L. monocytogenes contamination in different ready-to-eat (RTE) foods sampled at retail or in the processing plant, including:
      • the frequency at which presence of L. monocytogenes in RTE foods is detected (including sample size, number of positives, total number tested for a specified time period, and test method); and
      • the number of L. monocytogenes cells present per amount (unit volume or weight) of contaminated RTE food (including method used).
    • L. monocytogenes survival and growth dynamics in RTE foods, including:
      • data or models on survival and growth of L. monocytogenes in specific RTE food matrices, including the potential effects of commensal microflora;
      • data or models on survival and growth of L. monocytogenes in the presence or absence of substances that inhibit or retard growth; and
      • data or models on survival and growth of L. monocytogenes at different storage temperatures and over different storage times.
    • The relationship between the dose of L. monocytogenes ingested with food and the frequency of listeriosis, including:
      • the effect of age, health status, or other characteristics of the consumer on the dose-response relationship;
      • the effect of food matrix and product formulation on the dose response relationship;
      • the effect of genetic characteristics of the L. monocytogenes strain on the dose-response relationship; and
      • any other data pertinent to L. monocytogenes dose-response relationships.
    • Current food consumption practices in the United States, including:
      • the frequency with which different RTE foods (e.g., deli meats or cheeses manufactured with growth inhibitors) are consumed by population subgroups (e.g., general adult population, pregnant women, the elderly); and
      • serving sizes for different RTE foods.
    • Food production practices in the United States that may impact L. monocytogenes prevalence, concentration, survival, or growth in RTE foods, including:
      • absolute or relative frequency with which different RTE foods are manufactured with substances that inhibit the growth of L. monocytogenes, and the types and concentrations of growth inhibitor used;
      • absolute or relative amount of specific types of RTE foods that are prepared, sliced, cut, or repackaged in retail operations, as opposed to being sold pre-sliced/pre-cut;
      • absolute or relative amount of different RTE foods manufactured without growth inhibitors that are prepared, sliced, or repackaged at retail;
      • average shelf life of foods that were identified in the 2003 Interagency Quantitative Assessment of the Relative Risk to Public Health From Foodborne Listeria monocytogenes Among Selected Categories of Ready-to-Eat Food as supporting L. monocytogenes growth;
      • average shelf life of RTE foods that were not explicitly identified in the 2003 risk assessment, but that may conceivably support L. monocytogenes growth;
      • ability of current production practices to prevent or reduce L. monocytogenes contamination in finished product;
      • ability of current operational practices in retail operations to prevent or reduce L. monocytogenes contamination in the final product at the time of sale; and
      • ability of current postprocessing practices to prevent L. monocytogenes cross-contamination after processing.
    • Storage times and temperatures that may affect L. monocytogenes growth during transport and storage of foods in the consumer's home.
       

    Research Needed: Hepatitis A Virus Associated with Consumption of Fresh and Fresh-Cut Produce

    • Improved methods for rapid detection of HAV in various types of produce are needed.
    • What are the frequency and levels of HAV in produce at every stage of the farm-to-fork continuum?
    • What disinfectants are adequate against HAV?
    • What is the actual infective dose of HAV? (Available dose-response data are not sufficient for understanding the relationship between exposure to HAV from consumption of produce and illness in different subpopulations.)
    • What is the current burden of illness due to HAV in fresh and fresh-cut produce?
    • In a given case or outbreak, what is the source of HAV infection? (Currently, sources are unknown for 65.2% of infections).
    • Under what storage conditions (e.g., temperature, humidity, and pH), is HAV stable in produce?
    • What are the effects of potential treatments and techniques that could be applied to irrigation water to inactivate HAV, such as activated carbon, reverse osmosis, membrane filtration, and diethylenetriamine?
    • Are contaminated utensils sources of outbreaks of foodborne hepatitis A (i.e., transfer rates of HAV from utensils to food)?
    • What is the role of consumer behaviors, such as hand-washing and cleaning of utensils and food-contact surfaces, in produce-associated HAV infection?
    • What are the transfer rates of HAV from hands to food when gloves are worn?
    • What is the effect of hand washing on contamination of produce and subsequent illness with HAV?
    • What is the effect of mucosal immunity on HAV? Can an immunized person, either by natural infection or by passive immunization, be an asymptomatic carrier?  Can HAV remain stable and replicate in the intestinal cells of an immunized person without causing illness?
       

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