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| Agenda Item 5 | GF 02/9 |
second fao/who global forum of food safety regulators
Bangkok, Thailand, 12-14 October 2004
(Paper prepared by the FAO/WHO Secretariat)
An adequate and safe food supply is critical for normal growth and development and to maintain health across the life span. Although the true global incidence of food borne diseases is difficult to estimate, it is clear that many people fall ill and die as a result of eating unsafe food. Surveillance of food borne disease is an important tool for maintaining the safety of the food supply. It is instrumental in estimating the burden of food borne diseases, identifying public health priorities, evaluating disease prevention and control programmes and assessing the relative cost of control measures. It allows rapid detection and response to disease outbreaks and helps identify emerging food safety issues and research needs. In addition, it is a major source of information for conducting risk assessment as part of the new risk analysis framework. Within this framework surveillance data is of paramount importance for conducting a risk assessment and eventually for formulating risk management options and implementing risk communication (1).
Countries differ in their public health systems, giving rise to a wide variation in national surveillance systems including surveillance systems for food borne diseases. Notably, in many countries the disease surveillance systems do not necessarily focus on food borne diseases. This paper provides a description of the important aspects of a well-functioning food borne disease surveillance system including its link to rapid alert systems in the food safety arena. For the purpose of this paper food borne disease surveillance is defined as the ongoing systematic collection, collation, analysis, interpretation and use of information relevant to the assessment, prevention and control of food borne disease. This includes epidemiological and microbiological information about pathogens and toxins in food animals and foods, sometimes referred to as monitoring (1).
There are various levels of intensity and coordination in national surveillance systems. Surveillance can be active or passive, general or sentinel, continuous or intermittent, disjointed or integrated. In general, the intensity of surveillance is a product of social (i.e. priority of disease, societal impact), practical (i.e. availability of epidemiological knowledge) and financial factors. The main objectives of food surveillance are detection of contamination, evaluating control interventions, and monitoring the progress towards a control objective and programme performance. However, surveillance is not merely a routine measure of the current situation (as opposed to monitoring), but a basis for giving qualified feedback to producers, tracing back contamination to its origin, pin-pointing critical (control) points during production and initializing response actions (2).
Many Member States maintain surveillance systems for communicable diseases, which are collaborative efforts based on passive or active surveillance systems and often include a requirement for mandatory reporting of specific diseases and the pathogens that cause them. Many of these existing surveillance systems have the capacity to detect clusters of food borne disease, provided the cluster is large enough and the effects severe enough to cause people to seek medical attention. However, the focus of these systems is communicable diseases, and their capacity to detect and investigate food borne illness rapidly may be limited (3).
A number of Member States already maintain surveillance systems to detect and investigate food borne illnesses caused by food borne pathogens. In many cases these systems are passive and rely on reporting by laboratories or physicians. Statistical analysis of information from such systems can reveal unusual clustering of illnesses by time or geographical area as compared with baseline values. Unfortunately, passive surveillance systems result in underreporting of disease, because only a small fraction of ill people seek medical care or submit samples for laboratory analysis. Furthermore, laboratories only test for a limited number of disease-causing agents and thus report only selected information to health officials (3). In most cases, hospital laboratories are not equipped to analyze for chemical contaminants present in food. This, in combination with the fact that most diseases caused by chemical contaminants result in nonspecific symptoms, leads to a situation where the burden of disease estimates obtained from most surveillance systems do not include estimates on the part of the disease burden that is related to chemical hazards in food.
Some countries maintain active food borne disease surveillance systems to determine the burden of disease from food borne pathogens more accurately. England, the Netherlands and the United States were among the first countries to conduct special studies to understand the disease burden attributable to food borne pathogens. Following this ‘first generation’ of studies, a number of other countries, including Australia, Canada and Ireland, launched similar studies. Studies from all these countries fall into two general designs: (i) prospective cohort studies with community etiology components or (ii) cross sectional surveys with or without supporting targeted studies. Although the design determines specific outcomes, all of these studies share the same overarching goal of defining the magnitude of acute gastrointestinal illness by taking into account under ascertainment and determining the proportion of acute gastrointestinal illness attributable to food. Researchers from each of these countries continue to work together closely, sharing research tools, reviewing and analyzing data and discussing future research goals. These active surveillance systems increase the timeliness of information and provide information on the baseline incidence of food borne illness, which is needed to measure the effectiveness of control measures (4).
Most national surveillance programmes aimed at ensuring that food does not contain unacceptable levels of contaminants are designed to measure selected chemical contaminants in a variety of raw agricultural commodities. Since the concern for chemical contamination is chronic disease and not acute illness, surveillance for chemical contaminants focuses on ensuring that the level of contaminants is below a predetermined maximum allowable limit rather than linking the contaminant level to an acute illness. When chemical contaminates are below the maximum allowable limit, consumers can be assured that the product has been produced according to good agricultural practices and their exposure to the chemical contaminant will be below the established acceptable daily intake level.
By virtue of the international nature of travel and trade, food safety has increasingly become a global issue. There have been many documented cases of contaminated of food from one country causing significant health effects in other parts of the world (3). Couple the massive global trade of food and animal feeds with other factors affecting the global food supply and safety such as population growth, poverty, adverse climatic and social events; and the need for a globally coordinated strategy to control food illnesses becomes acutely apparent.
Concerns about the global spread of food borne disease can best be addressed through strong surveillance systems, renewed commitment to public health, and strong international partnerships that strengthen national efforts of food borne disease prevention and control. In view of the disparity among national surveillance systems, partnerships in global surveillance are a logical starting point.
To be effective, global surveillance must be free of political bias. Global surveillance requires a neutral reporting and response environment. WHO is the international health organization with a primary mandate to protect public health and to provide technical assistance and advice to Member States on all health issues. In 1969, WHO adopted International Health Regulations (IHR) after agreement by the international community. These regulations represent the only regulatory framework for global public health security. The IHR prevent the international spread of infectious diseases by requiring national public health measures that are applicable to travelers and products at the point of entry. While the current IHR require Member States to notify WHO only of all cases of cholera, plague and yellow fever; the IHR are undergoing revision to meet the increasingly complex risks of existing and emerging infectious diseases. The revisions proposed include a requirement to notify WHO of all public health emergencies of international concern. In view of the need to contain disease and public health risks at their origin and to minimize international control measures, Member States would be obliged to identify and control all events of international public health importance, including infectious and non-infectious diseases as well as unacceptable levels of microorganisms, toxins and chemicals in food (3).
The new proposed IHR will provide guidelines for implementing the required surveillance and response programmes for public health emergencies. Essential elements of the programme include rapid detection and reporting of public health emergencies, verification and preliminary control measures and response capacity, including notification to WHO of events or risks of international significance. This includes notification of a need for assistance to contain or control further spread of the contamination, and for travel and traffic restrictions on the movement of people, conveyances and goods including food, plants and animals. Information and recommendations developed by WHO will serve as a guide for responses appropriate to the actual health risk (3).
In 2000, the 53rd World Health Assembly (WHA) adopted a resolution to recognize food safety as an essential public health function and called for the development of a Global Strategy for reduction of the burden of food borne diseases. The resolution WHA 53.15 encouraged Member States to implement and keep national, and when appropriate, regional mechanisms for food borne diseases surveillance. In 2002, WHO published a Global Strategy for Food Safety (5). The overall objective of this strategy is to strengthen surveillance of food borne disease to provide Member States with the data necessary to reduce the burden of food borne disease.
A recent the WHO Expert Consultation defined four surveillance categories (No formal surveillance, Syndromic surveillance, Laboratory-based surveillance, Integrated food-chain surveillance) and discussed the feasibility of establishing sentinel surveillance in regions lacking reliable food borne disease estimates. The attributes of each of these four surveillance systems are summarized in Table 1. Following this consultation, studies on the burden of food borne disease in developing countries were initiated. Jordan has been selected as the first sentinel site for this project and the selection of additional sites is underway1(6).
Table 1. Surveillance systems in relation to the assessment of the burden of disease
| Surveillance Category | Expected Outcomes | Contribution of Surveillance System to Burden of Disease Assessment | External Support Required to Conduct Burden of Disease Assessment | Resources and Cost Associated with Conduction Burden of Disease Assessment | Ability of Surveillance System to Attribute Disease to Specific Food Sources | Usefulness of Surveillance Data to Contribute to Risk Analysis |
| 1. No formal surveillance | Non-specific disease parameters | None | High | Minimal | None | None |
| 2. Syndromic surveillance | Non-specific disease parameters | Limited | Moderate | Minimal | None | Limited |
| 3. Laboratory-based surveillance | Etiology-specific, including subtypes | Potentially significant | Minimal | Increased complexity, laboratory and epidemiological cost | Moderate | Potentially significant |
| 4. Integrated food-chain surveillance | Etiology-specific, including subtypes, greater precision, population-based reservoirs | Significant | None | Increased complexity, laboratory and epidemiological costs, including food and agricultural laboratories | High | High, allows validation of models |
Table adapted from (6).
In order to engender the political will required to initiate and sustain a strategy to reduce food borne disease, the magnitude of the problem must be determined. Global surveillance information can also be used by countries to perform rapid risk assessments and prioritize food safety needs. WHO has implemented a number of sentinel site programmes to develop special studies in regions currently lacking good data on food borne illnesses and has created a network connecting countries involved in these surveillance activities related to acute gastrointestinal illnesses. One of the global programmes designed to strengthen surveillance of food borne disease is Global Salm-Surv. Global Salm-Surv is a laboratory based surveillance system that has been operational since January 2000. It consists of a network of institutions and individuals involved in Salmonella surveillance, serotyping and antimicrobial resistance testing. This programme, initiated by the WHO, the Danish Veterinary Laboratory (DVL) and the Centers for Disease Control and Prevention (CDC) and now also supported by the Institute Pasteur, United States Food and Drug Administration, Health Canada and Wageningen University; endeavours to reduce the global burden of food borne disease by strengthening national and regional surveillance and response activities (7). The WHO Global Salm-Surv external quality assurance system (EQAS) is an important step toward improving the quality of Salmonella serotyping and antimicrobial susceptibility testing worldwide (7). The core elements of the Global Salm-Surv programme include regional training workshops, a moderated electronic discussion group, an external quality assurance system, a country databank of annual Salmonella surveillance summaries, a web site http://www.who.int/emc/diseases/zoo/SALM-SURV/index.html, and reference testing services. Training workshops for microbiologists and epidemiologists have involved numerous representatives from almost 100 countries from all six WHO designated regions.
WHO also monitors and performs exposure assessments of chemical contaminants in food. The WHO Global Environmental Monitoring System/Food Contamination Monitoring and Assessment Programme (GEMS/Food) provides information on the concentration of chemical contaminants in food, their contribution to total human exposure and their significance for public health and trade. GEMS/Food provides baselines of chemical contaminants in food that may be used to assess contamination. The Programme is an important component of the global risk assessment of chemicals in food and provides exposure assessments that form part of the basis for setting national and international food safety standards. GEMS/Food maintains a network of WHO Collaborating Centres, national focal points and participating institutions located in over 70 countries. It maintains links with international organizations such as Food and Agricultural Organization (FAO), International Atomic Energy Agency (IAEA), the United Nations Environment Programme (UNEP) and nongovernmental organizations such as the International Union of Food Science and Technology (IUFoST) and the International Union of Pure and Applied Chemistry (IUPAC)(3).
Under the WHO Programme on Global Alert and Response, WHO has established a mechanism for providing accurate and timely information about important disease outbreaks. This information is delivered systematically and rapidly to key professionals in international public health through the international networks for specific disease surveillance including FluNet for influenza, RabNet for rabies, Global Salm-Surv for salmonellosis and DengueNet for dengue (3).
Outbreak verification is a new approach to global disease surveillance that aims to improve control of epidemics by active collection and verification of information on reported outbreaks. Verification of outbreaks is based on a broad range of sources of information, including the Global Public Health Information Network (GPHIN). GPHIN is a Web-based electronic system developed by Health Canada in collaboration with WHO, which scans the Web to identify suspected disease outbreaks. The suspected outbreaks are followed up with the affected countries to verify the existence of the epidemic, its cause and the control measures being taken. The information is then disseminated via the outbreak verification list to over 900 institutions and key decision-makers in international public health, such as WHO Collaborating Centres, national institutes of public health and the major non-governmental organizations. Since 1996, over 500 outbreak reports have been investigated and the information disseminated when it was found to be of international public health importance. WHO offers assistance in all cases (3).
The WHO Global Outbreak Alert and Response Network (GOARN) provides immediate public health assistance for the containment of disease outbreaks. The Network provides a coordinated mechanism for outbreak alert and response. It consists of a technical partnership between institutions and networks and complements existing systems. Its role is to combat the international spread of outbreaks by rapid identification, verification and communication of threats, leading to a coordinated response. It ensures that appropriate technical assistance reaches the affected Member State rapidly, minimizing the health impact of the outbreak and preventing further spread of disease. WHO responds to requests from Member States for assistance in outbreak management by fielding special teams of experts. Recent examples of outbreaks in which WHO participated directly in the field include: Rift Valley fever in Kenya and Somalia, monkey pox in the Democratic Republic of Congo, avian influenza (H5N1) in Hong Kong (China)(3).
In addition to providing necessary information for monitoring outbreaks of food borne diseases and evaluating control measures, global surveillance can serve as an early warning system for food outbreaks and provide the rationale for public health intervention including the cessation, and resumption, of trade. Early detection of food borne diseases and immediate public health intervention can not only limit the number of illnesses and deaths, but also lessen the negative effects on international travel and trade. Global food borne disease surveillance and response is a decisive element in maintaining public health and facilitating trade of food, plants, animals, and animal products (8).
WHO, together with FAO, is now enhancing its ability to respond to food borne disease emergencies by establishing an International Food Safety Authorities Network (INFOSAN), an information network for the dissemination of important information about global food safety issues. In January 2003, WHO identified the need for a food safety network to complement and support the existing WHO information and response programmes. INFOSAN is designed to enhance the ability of the GOARN Network to combat the international spread of food borne disease by rapid identification, verification and communication. Embedded in INFOSAN is INFOSAN EMERGENCY, this food safety emergency network will help to minimize the health impact of food borne disease outbreaks and prevent further disease spread by an implicated food (8).
Each participating country will have one or several INFOSAN Focal Points. The INFOSAN Focal Points are expected to receive INFOSAN information and disseminate it. Several INFOSAN Focal Points may be identified in countries where responsibilities are divided among several food safety authorities, including those involved in food legislation, food control and management, food inspection services, laboratory services for monitoring and surveillance, and information, education and communications, across the so-called farm-to-fork continuum (8).
Each country will have one dedicated INFOSAN EMERGENCY contact point that, in addition to receiving the general information, will be activated to deal with major international incidents involving an imminent risk of serious injury or death to consumers. INFOSAN EMERGENCY will be used to alert food safety authorities to food borne disease outbreaks or food contamination events of international significance. The INFOSAN EMERGENCY Contact Point will be expected to accept some notification and response responsibility and to facilitate the communication of urgent messages during food safety emergencies. INFOSAN EMERGENCY will be closely linked to the GOARN Network (http://www.who.int/csr/sars/goarn/en/ index.html) at both the national and international levels. INFOSAN and INFOSAN EMERGENCY are limited to government entities or entities appointed by government (8).
Many countries have well developed, established surveillance systems for monitoring food and the environment for chemical contaminants such as dioxins, PCBs, heavy metals and residues of pesticides and veterinary drugs. Surveillance systems directed at food borne pathogens are more recent as are microbiological risk assessments and pathogen reduction programmes. The development of a comprehensive food safety surveillance framework not only enables the continued assurance of food safety regarding known chemicals and pathogens, but provides a mechanism to protect against emerging hazards.
The application of modern biotechnology to food production presents new opportunities and challenges for human health. The potential benefits to consumers include enhancing the nutrient content of foods, decreasing their allergenic potential, and improving the efficiency of food production. On the other hand, the potential effects on human health of the consumption of food produced through genetic modification must be carefully examined. Modern biotechnology must be thoroughly evaluated if it is to bring about a true improvement in our way of producing food. Having a fully functioning, global food safety surveillance network will provide an added measure of confidence to consumers across the world that the safety of food produced by genetic engineering is being monitored.
Antimicrobial agents are essential medicines for human and animal health and welfare. The development of antimicrobial resistance is a global public and animal health concern that is impacted by both human and non-human antimicrobial usage. A comprehensive food safety surveillance framework will not only be capable of the monitoring food borne pathogens but will be capable of determining the development of antimicrobial resistance in these pathogens when it is associated with the use of antimicrobials in agriculture and veterinary medicine. This information is critical for determining risks associated with the development antimicrobial resistance for specific microorganism-antimicrobial combinations and for developing risk management options aimed at reducing the risk associated with the use of antimicrobials in agriculture and veterinary medicine.
The intentional malicious contamination of food is not a new threat. However, the centralization of food production and the wide spread distribution of food enhances the potential public health impact of intentional food contamination. The potential impact on human health of deliberate sabotage of food can be estimated by extrapolation from the many documented examples of unintentional outbreaks of food borne disease. The largest, best-documented incidents include an outbreak of S. typhimurium infection in 1985, affecting 170 000 people, caused by contamination of pasteurized milk from a dairy plant in the United States of America. An outbreak of hepatitis A associated with consumption of clams in Shanghai, China, in 1991 affected nearly 300 000 people and may be the largest food borne disease incident in history. The number of people impacted by an intentional contamination incident is likely to be considerably higher.
In 2002, WHO published a report on "Terrorist Threats to Food: Guidance for Establishing and Strengthening Prevention and Response Systems" (3). This report identified two major strategies for countering the threat of food sabotage, i.e., prevention and response, including preparedness. According to the report, the key measures needed to prevent food terrorism include the establishment and enhancement of existing food safety management programmes and the implementation of reasonable security measures.
Detection of the food contamination is needed to activate a response.
The main requirement for rapid detection of covert or overt acts of food terrorism is a surveillance system with the sensitivity to rapidly identify small clusters of food borne illness. Such systems permit identification of disease outbreaks, whether intentional or unintentional, but do not necessarily permit the identification of the disease or its mode of transmission. Strong national surveillance systems provide information on the expected frequency and size of various disease outbreaks, thus providing a baseline for identifying unusual clusters that might herald a terrorist incident. Early detection of disease resulting from food terrorism will depend upon sensitive general surveillance systems for communicable disease at local and national levels, with close cooperation and communication among clinicians, laboratories and public health professional. Once food terrorism is detected, there is a need to activate response systems including verification of the threat, management of the consequences by aiding the affected population, identification and removal of the food from sale and management of the social, political and economic consequences of the act (3).
The report concluded that effective preparedness for food terrorism requires both strengthening of the general public health surveillance and improving coordination and communication among the sectors responsible for an emergency response. The lack of integrated surveillance, epidemiological and laboratory activities and lack of preparedness planning for emergency response in many developing countries are still significant obstacles to effective detection and response to threats posed by the deliberate as well as unintentional introduction of hazardous agents into food (3). The assistance of WHO and FAO can help prevent, quickly detect and mitigate the effects of food terrorism, as well as the effects of unintentional food borne outbreaks and contamination events. The new INFOSAN network is intended to support this work.
Both industrialized and developing countries can best address concerns about food borne disease including those from new technologies and intentional acts of terrorism through strong surveillance systems, renewed commitment to public health and strong international partnerships. There is a need for a common high standard of food safety to protect consumers worldwide. Surveillance programmes serve as a tool for monitoring and continuous improvement of food quality through detection of food borne illnesses or contamination in food production and initiation of appropriate responses. Since the challenge is to produce safe food at affordable prices, surveillance programmes need to be sensitive, sensible and cost efficient. Currently, the infrastructure and capacity needed to efficiently coordinate and operate national food borne contaminant and food borne disease surveillance programmes varies among countries worldwide. International Organizations have a major role to play in promoting integration of food safety surveillance at the national and international level.
The WHO and FAO have a critically important roles to play in food safety at the international level. The WHO, in many cases in direct collaboration with FAO, functions to implement the International Health Regulations (IHR); coordinate worldwide disease surveillance networks; and coordinate international responses to communicable diseases. FAO and WHO work to assess the health risks associated with chemical and biological agents and radio nuclear materials and the potential to mitigate such risk as well as support the development of food safety infrastructure in Member States. These functions place these Organizations in a unique position to play a key role in: 1) the coordination of global surveillance for food safety emergencies; and 2) the facilitation of responses to food emergencies of international significance to human health; and 3) the provision of technical assistance for national preparedness and response. The development of INFOSAN and INFOSAN Emergency will enhance the efforts of WHO and FAO in providing the world with a safe food supply.
1 The criteria for assessing the suitability of a country for inclusion in a burden of illness study were defined as: (i) lack of data on burden of foodborne disease in the country and the region, (ii) preferably in surveillance category 3 (laboratory based surveillance), (iii) availability of data on food consumption and contamination, (iv) the extent and nature of scientific and technical resources and infrastructure, (v) preference given to countries with geographical diversity, (vi) selecting a country with a broad representation of ethnicity and socio-economics and (vii) insuring that duplicate efforts by other organizations have not been done.