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EPID: Focus on Surveillance
Role of Attribution in Global Food Surveillance**

Robert E. Brackett, Ph.D., M.S.
Vice President and Director, National Center for Food Safety and Technology
Illinois Institute of Technology
 
 
 

Summary

 
The safety of the food supply has emerged as an important and complex global public health, social, and political issue.  Although accurate statistics on the scope of foodborne illness are lacking, the World Health Organization (WHO) estimates that millions of individuals die each year from diarrheal diseases, many from contaminated food and water.  Moreover, the economic cost of foodborne illness in the U.S. alone could be as much as $152 billion (U.S.) per year.

 
Surveillance is vital to providing accurate information on the impact of foodborne illness.  Accurate and timely surveillance is needed to limit the scope of outbreaks, identify recognized and emerging sources of foodborne pathogens, and provide critical data for robust risk assessments.  In addition, accurate surveillance statistics form the basis for developing and implementing mitigation strategies and directing appropriate national and international food safety policies.  However, the current surveillance system in those countries that have them possesses only limited capability and capacity to provide the type and amount of data that stakeholders would need to implement a public health-targeted food safety policy.
 
Currently available surveillance statistics are valuable in terms of identifying and quantifying causality and developing public health goals for implicated microorganisms but lack the specificity required to make meaningful decisions needed to improve food safety.  To do so, surveillance must be able to identify the food in which the organism was present and the geographical region from which the food or food ingredient originated.  The term attribution is typically used by public health experts to describe the ability of a surveillance system to link cases of foodborne illness to a specific food or ingredient.
 
An ideal surveillance system would have to be national or international in scope, but would also require participation at the local and state/provincial level.  Although attribution requires considerably more human resources than does conventional surveillance, advances in trace-back technologies, molecular typing and epidemiology, mathematical modeling of epidemic patterns, and advance computing and database management could be employed in the future to minimize the need for personnel while speeding up data collection and analysis.
 
 

Current realities

 
Accurate attribution of foodborne illness to specific food vehicles is an important goal for both the private sector and the public health community.  However, that goal has been largely unattainable given the scope and complexity of the problem and the limited effort being given to achieving the goal.  The current realities illustrate the scope and reasons why attribution has not occurred as desired.
 
The most recent estimates published by the U.S. Centers for Disease Control and Prevention (CDC) estimate that as many as 76 million cases, 325,000 hospitalizations, and 5,000 deaths are caused by foodborne illness each year in the U.S.
 
Current surveillance systems are primarily focused on the organism rather than the vehicle (food).  Without knowing the vehicle, developing strategies to improve safety is hampered.
 
In many countries, there is significant underreporting of foodborne illness.  Consequently, emerging pathogens and foods of potential concern are missed.
 
Recent outbreaks have involved foods that were previously thought to be low-risk.  Likewise, many of the largest outbreaks have been traced to unidentified ingredients in complex, multicomponent (multi-ingredient) foods.
 
Federal research efforts are focused on fundamental rather than applied solutions.  Attribution would provide the basis for additional funding on microbial ecology of foods, mitigation strategies, and detection methodologies for organisms in foods of highest concern.
 
Food safety has become a major issue in international trade, and foreign-sourced food makes up a growing percentage of food for most countries.  Food safety is sometimes used as a trade barrier and excuse for countries to limit imports.
 
Most regulatory decisions, while saying they are risk-based, are typically NOT based on public health data.  Little data exists on which to base risk-based decisions.  Hence, current regulatory policy tends to be more “overarching” rather than focused on foods and practices/processes of greatest risk.

 
 

Scientific opportunities and challenges

 
Acquiring knowledge of which specific foods are of highest risk for certain pathogens will help identify novel new processing techniques to improve safety.
 
Identification of high-risk foods, contributing factors, and environmental antecedents can help to focus risk assessments more effectively.  Risk assessments are required by the World Trade Organization (WTO) in trade disputes involving food safety issues.  As more data is available for such risk assessments, the validity and utility of their results to the scientific community increases.
 
Advances in communication and sharing of vital food safety data by the food industry and domestic and international public health agencies can enhance early identification of problems.  An example of the contribution of such communications networks is the CDC’s PulseNet system for comparing genetic fingerprints of foodborne pathogens.  The implementation of PulseNet is largely responsible for early identification of most of the multistate foodborne outbreaks in recent years.
 
Expanded use and the development of new and more refined techniques for molecular epidemiology and typing can help match specific strains of pathogens to ecological niches (foods).  In addition, it enables investigators to trace contaminated foods and ingredients back to their sources (a process known as traceback).
 
 

Policy issues

 
Attribution of foodborne illnesses could have major policy implications.  Attribution of illness to a specific commodity, region, or brand could change the level of risk category to which that commodity is assigned.  This could increase regulatory scrutiny and actions for that commodity, influence policy decisions aimed at that category of food, and affect international trade.  In contrast, having the ability to attribute illnesses and outbreaks to more specific circumstances would allow more informed public health decisions, improved public messaging, more focused government research funding, effective preventive controls regulation, and increased confidence in governments and trading partners.
 
  • Current and future regulatory actions are dependent on identifying the most effective corrective or preventive strategies.  Better attribution must be employed so that policy makers and regulators can focus on highest-risk foods and pathogens and make more effective public health decisions.  Key implementers of attribution strategies include local, national, and international regulatory agencies working closely with surveillance agencies, such as state departments of health, the CDC, and the WHO.

  • Food safety issues can impact both international trade as well as public health.  Because a large percentage of foods and ingredients is traded in international commerce, adulterated products produced in one part of the world can cause major outbreaks in another part of the world.  It is critical that public health officials, regulators, and food companies have a means to attribute contamination to the correct source. The inability to do so is cause for mistrust between trading partners, flawed trade policy, and destabilization of prices.

  • Federal budgets have tended to fund fundamental research which focuses on mechanisms of disease but have largely ignored applied research to prevent foodborne illness.  A better balance of federal funding must be achieved to improve food safety through the acquisition and use of attribution data.

  • Building an effective attribution system will require significant funding.  Much of this funding will need to be directed to local/state/provincial partners who actually conduct the surveillance and to developing standardized data collection systems so that data from multiple sources (local, state, provincial) can be rapidly collected and analyzed.  Hence, it will be necessary to inform and convince government leaders that such a system will result in measurable improvements to public health.

  • Some countries have implemented national mandatory reporting for all foodborne illness.  Such mandatory reporting is a critical first step in achieving a global foodborne illness attribution system and should be implemented by all countries which trade in agriculture and food.
 
 
** A policy position paper prepared for presentation at the conference on Emerging and Persistent Infectious Diseases (EPID): Focus on Surveillance convened by the Institute on Science for Global Policy (ISGP) Oct. 17-20, 2010, at Airlie Conference Center, Warrenton, Va.
 
 

Debate summary

 
The following summary is based on notes recorded by the ISGP staff during the not-for-attribution debate of the policy position paper prepared by Dr. Robert Brackett (see above).  Dr. Brackett initiated the debate with a 5-minute statement of his views and then actively engaged the conference participants, including other authors, throughout the remainder of the 90-minute period.  This Debate Summary represents the ISGP’s best effort to accurately capture the comments offered and questions posed by all participants, as well as those responses made by Dr. Brackett.  Given the not-for-attribution format of the debate, the views comprising this summary do not necessarily represent the views of Dr. Brackett, as evidenced by his policy position paper.  Rather, it is, and should be read as, an overview of the areas of agreement and disagreement that emerged from all those participating in the critical debate.
 
 

Debate conclusions

 
  • Given the reliance on the global food supply chain and the increasing international awareness of terrorism, surveillance of foodborne illnesses as well as events involving intentional contamination of the food chain have become a priority.  In general, food safety and security has become a national security issue.
 
  • The use of ingredients sourced from numerous international suppliers, together with the just-in-time delivery system itself, emphasizes the need for surveillance systems that can quickly identify the specific vehicle and pathogen/agent involved in a given food safety incident.
 
  • Some surveillance systems, such as PulseNet, have proven to be successful and should continue to be replicated and expanded internationally.
 
  • Surveillance systems having diverse objectives (e.g., monitoring the safety of food versus the health of animal or human populations) need to more accurately recognize and utilize the operation of the common food delivery infrastructure.
 
  • It is increasingly recognized that surveillance focused on preventing natural and intentional harm to the food supply is required to ensure the security and prosperity of a country.  The responsibility for such surveillance involves both domestic and international policy decisions.
 
  • Developing greater working partnerships between industry and government is essential to creating an effective food surveillance system.
 
 

Current realities

 
Repeated food safety incidents, such as the cases of Salmonella (in peppers, peanut butter, and eggs) and Escherichia coli (E. coli) (in ground beef) have eroded the public’s trust in the food industry and food safety regulatory agencies.  In the United States alone, a recent Pew Trust report found that such food safety incidents cost more than $152 billion (U.S.) due to medical costs (not including lost productivity).  The current food surveillance system is not quick enough and does not allow for attribution that is specific enough to help make timely policy and disease management decisions.
 
There was agreement that the food surveillance systems in some U.S. states have proved to be effective, some even outstanding, as demonstrated by their repeated success at regularly unraveling foodborne disease outbreaks.  Additionally, it was highlighted that some U.S. states have a good framework for disease surveillance while others must more heavily rely on help from the federal government.  Foodborne Diseases Active Surveillance Network (FoodNet) and PulseNet, both managed by the Centers for Disease Control and Prevention (CDC), were cited as successful surveillance initiatives.
 
FoodNet, a component of CDC's Emerging Infections Program (EIP), is a collaboration involving the CDC, 10 EIP sites across the U.S., the U.S. Department of Agriculture (USDA), and the Food and Drug Administration (FDA).  PulseNet is a network of public health and food regulatory agency laboratories across the U.S.  The PulseNet laboratories perform standardized molecular sub-typing (or “fingerprinting”) of foodborne disease-causing bacteria by pulsed-field gel electrophoresis (PFGE).  These DNA patterns are submitted electronically to a dynamic database at the CDC and are available on demand to participants, thereby allowing for rapid comparison of the patterns and quicker identification of related cases or outbreaks.  However, compliance of healthcare professionals with these programs varies for different reasons, including cost and time associated in culturing fecal samples. While there are numerous similarities in procedures and common infrastructures among these surveillance systems, differences exist that reflect the various subjects or survey populations examined as well as different laboratory networks and capacities.  These types of disease surveillance systems have been successfully replicated internationally, leading to programs such as PulseNet International.  Such efforts should be expanded.
 
Because of the damage and negative public backlash suffered by the food industry as a whole when a few producers are negligent, the private sector is willing to vigorously assist regulatory agencies in investigating food incidents.  Negative food incidents are a detriment to the food industry because they lead to loss of public trust and eventually to decreased market share.  The discussion recognized that surveillance systems have not always correctly determined the cause of a food incident, which has led to economically disastrous policy or regulatory decisions.  This was exemplified by the wrongful blame placed on the tomato industry during the 2008 Salmonella outbreak, which eventually was attributed to peppers instead of tomatoes.
 
As a whole, the existing food regulatory and surveillance system is fragmented and not very efficient.  This is due, in part, to numerous agencies being charged with responsibilities for different food products.  However, an absence of political will and outdated laws currently prevent meaningful changes from being undertaken.  The budgets and human resources allocated to many of these agencies are not sufficiently large to permit them to meet their mandated responsibilities for disease surveillance in foods.  In addition, every year, the FDA audits few of the food production facilities it regulates.
 
It was widely agreed that a terrorist act carried out through the food system in the U.S. is highly improbable.  Yet, it was also noted that a terrorist attack on the food supply could be catastrophic, not only in terms of the morbidity and mortality involved, but also because of the economic damage that would be done.  The food industry is especially vulnerable because of its reliance on the “just-in-time” model in which products are constantly on the move and often reach the end user within hours after being manufactured.  The food supply chain is highly complex, involving the global import of ingredients to be used in multi-ingredient products requiring rapid transport and distribution.  Such an attack on the food supply can also be anticipated to have catastrophic impact on a wide range of corporate activities in general, and therefore have seriously harmful consequences for the country at large. 
 
Vulnerabilities in the current food system have been shown through the intentional adulteration of products that ended up in the consumer channel, such as melamine-tainted pet food and dairy products.  An improved surveillance system with better attribution could be used to identify such incidents earlier and would be able to trace offending ingredients to their origins. Economically motivated adulteration of food is an important problem that requires investigation.
 
Typically, disease surveillance is normally focused on identifying the pathogen or organism in the food associated with a specific incident and does not emphasize the longer-term issues of identifying the vehicle involved.  This separation of short- and long-term goals also reflects the efforts of governmental funding agencies in supporting research activities focused on basic research rather than supporting applied research having more specific, short-term goals.  The importance of applied research in strengthening disease surveillance systems was considered, especially since new technologies already exist that could be harnessed and applied to food surveillance.  These newly available techniques are exemplified by the use of genomics to identify pathogens or agents that have already made important contributions.  In general, however, these new techniques emerge from the successes of basic research and therefore it was recognized that supporting a blend of basic and applied research programs remains the correct direction to take.
 
The food industry does not always know which production chain modes on which to focus with regard to safety issues.  Novel or stealth foods have been involved in contamination and foodborne illness.  Contamination from these foods has rarely, if ever, been identified.  Pathogens present in these foods survive processing and sometimes even Hazard Analysis and Critical Control Point (HACCP) programs.
 
In some countries, food safety is directly related to food security and politics and often is not reflective of sound scientific understanding.  Food defense activities and negative events of intentional tampering are scalable and subject to copycat events, which may mask subsequent acts of tampering.  These events are scalable because of the nature of the food supply chain.  If an ingredient that is integral in many secondary products is intentionally contaminated, then many more people or countries are potentially affected.  This makes the need for an effective food surveillance system with better attribution critical.
 
 

Scientific opportunities and challenges

 
It was suggested that the HACCP system is becoming outdated.  This view was substantiated based on food incidents related to producers that had a HACCP program in place.  It was recommended that HACCP be used only in conjunction with other programs to improve the overall effectiveness of food safety programs.
 
The expansion of PulseNet was suggested for use with other molecular techniques to supplement pulsed field gel electrophoresis.  The use of these molecular techniques allows more specific attribution of pathogens involved in food incidents.  It was also suggested that surveillance should occur as far down the food supply chain as possible, targeting the individual ingredients used to produce composite products.  This procedure would mirror the surveillance currently used in the pharmaceutical industry.
 
 

Policy issues

 
Consensus was reached on the need to continue the expansion and replication of programs such as FoodNet and PulseNet, especially internationally.  These programs could be organized at regional levels as a mechanism to develop a more effective global system.  It was also strongly recommended that the food surveillance capacity of local communities, regions, and countries be significantly expanded and brought into compliance with globally accepted standards now under discussion.  Assessments of current local, countrywide, and national systems need to be conducted and the results made public.  Private sector companies would find this information exceptionally useful in their efforts to support business ventures in locations where robust food safety systems are required to ensure the quality of their products.
 
A change in the process of policy-making in the arena of surveillance, from a top-down to a bottom-up approach, was a common suggestion that was strongly supported.  This centered on the idea that many organizations, such as the World Health Organization (WHO), are not currently effective in meeting their mandate to conduct effective food safety surveillance.  By recognizing the needs of a given country and/or region through placing critical decisions with local authorities, the system would more effectively ensure food safety.  This bottom-up approach would foster the development of capacity at a local level.  It was also recognized that improvement in the capacity of existing international agencies, such as the WHO, is a component of a functional food safety system, since that is necessary to ensure the interoperability of surveillance systems created in different regions and/or countries.
 
It was strongly recommended that food surveillance systems need to be developed in parallel to the development of a complex food supply chain.  It was concluded that such coordination can be achieved by strengthening the partnerships among government, industry, and academia to ensure that food surveillance is conducted in a manner that recognizes the demands of a global food supply chain.
 
There was general consensus that it is necessary for funding agencies to redistribute the focus of their funding from basic research toward more applied research designed to provide the technology and data that would help governments and industry evolve food surveillance systems to meet the rapidly advancing needs and expectations of the public.
 
The debate identified the importance of characterizing the potential role of food in terms of a terrorist target.  Although there have not been significant cases of major terrorist attacks on the food supply, there are several examples where criminal acts involving intentional contamination of products (e.g., baby formula and Tylenol) have proved deadly.  Countries view the importance of food as a possible terrorist vehicle differently, and if an attack on the food supply was scaled to regional or national levels, it would represent a catastrophic event affecting not only human health but global economies.
 
The increased use of risk assessments for making policy decisions on food surveillance and food safety was strongly endorsed.  These risk assessments would generate better information for policy makers to use in formulating decisions.  Although in general there was agreement that templates for risk assessments and mitigation strategies should be standardized, allowing uniformity among local, regional, and international actors, there was some debate over who would develop and “own” these tools.
 
The idea of placing taxes on food products to provide funds for surveillance or regulatory functions was discussed, but not widely supported.  While it was indicated that the food industry would not support taxation, many believed that the food industry would instead be willing to financially support applied research that directly improves food safety.
 
There was disagreement on whether the food industry had reduced its focus on quality assurance in favor of using post-production surveillance to identify incidents of contamination before products reach end users.  It was agreed that it is ineffectual for industry to choose between these two measures, but rather that the food industry must consolidate prevention, surveillance, and quality assurance into one program to improve the safety of food products.
 
The suggestion was made to shift the responsibility for food safety from the producers back to the public through education.  However, it was felt that in today’s world of consumer advocate groups, this suggestion would not be supported due to the public’s increasing demands for safety guarantees.  Despite these demands, consumers themselves generally do not take responsibility for implementing even simple measures (e.g., proper cooking temperatures) that could drastically reduce the number of cases of foodborne illness.
 
Differing views were expressed concerning the effectiveness of Country of Origin Labeling (COOL) as a tool in strengthening surveillance.  In general, it was concluded that such labeling is ineffective.  While some viewed it as a useful tool because of the highly complex food supply chain, a final composite product may have ingredients from all over the world and the origin of suppliers may vary substantially as well.  It was believed that this dispersion would make effective traceback very difficult for a food incident.
 

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