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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Day 1 Afternoon Session     Surveillance for Foodborne and Diarrheal Diseases, Including Outbreak Investigations: An American Perspective         Foodborne Disease Investigations Including Surveillance: A Collaborative Pilot Project         Discussion    

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Surveillance for Foodborne and Diarrheal Diseases, Including Outbreak Investigations: An American Perspective William E. Keene, Ph.D., M.P.H. Senior Epidemiologist, Acute and Communicable Disease Program, Oregon Public Health Services CASE STUDIES Case studies of three important foodborne disease outbreaks are presented to illustrate how disease surveillance works in the United States and the evolution of outbreak investigative methods. These outbreaks can be reviewed in detail in the original literature (see also Barrett et al., 1994; Bell et al., 1994; CDC, 2004; Cody et al., 1999; Griffin et al., 1994). Outbreak 1 was the 1992-1993 Jack-in-the-Box outbreak of Escherichia coli O157:H7 infections that affected several western states. The outbreak was caused by widespread undercooking of contaminated frozen ground beef hamburger patties at many outlets of the Jack-in-the-Box fast food chain. Although infections from this source began to appear in California and Nevada as early as November 1992, the outbreak was not detected until it reached Washington state in late December. At that time only Washington state was conducting routine surveillance for these infections. In California and Nevada, in contrast, the infection was not reportable, and few laboratories ever used the special media needed to identify the pathogen. Physicians and the general public there were largely unaware of this pathogen; in the absence of recognized outbreaks, there was no publicity and no public education. This outbreak was a landmark event in modern epidemiological history. It had an enormous effect on the public’s perception of the problem of foodborne illness. The political ripples from this event continue to this day. We can quite reasonably talk about foodborne disease epidemiology in the United States before and after Jack-in-the-Box. The outbreak illustrates how large outbreaks with many hospitalizations and even fatalities can

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop easily escape notice, investigation, and control in the absence of routine disease surveillance. Outbreak 2, which occurred in 1997, involved E. coli O157:H7-contaminated, unpasteurized commercial Odwalla-brand apple juice. Advances in molecular subtyping of this organism and integration of laboratory subtyping with routine surveillance data made it easy (at least in Washington state) to identify this outbreak. Once the outbreak was identified, the source was quickly identified through traditional case interviews and a case-control study. The outbreak led to changes in the way fresh juices were labeled and processed. Outbreak 3, of Salmonella Enteriditis infections linked to consumption of raw almonds in the United States and Canada, was first identified and investigated in May 2004. But in retrospect, cases may have occurred as early as 2002. The outbreak led to changes in almond processing by industry, which is moving toward a ban on the sale of untreated almonds (i.e., raw almonds or those not processed in a way that would kill pathogens). INTRODUCTION TO DISEASE SURVEILLANCE Public health epidemiology has a number of goals. One is to monitor the health status of the population (e.g., indexes of morbidity and mortality) as well as the contributors to that health status (e.g., access to medical care, level of personal hygiene, and food consumption histories). Another is to manage health crises as they occur, including the investigation and control of disease outbreaks and the emergence of new pathogens (e.g., SARS, avian influenza, and bovine spongiform encephalopathy). Public health epidemiologists are also charged with providing and interpreting available scientific information to help inform public policy decisions. In this context, disease surveillance plays a major role. Surveillance was famously defined by Langmuir (1963) as the “ongoing systematic collection, collation, analysis, and interpretation of data; and the dissemination of information to those who need to know in order that action be taken.” Surveillance activities involve the collection of raw data, the “cleaning” (correction and standardization) of those data, and the organization and analysis of those data. It is axiomatic in modern public health practice that data are collected in order to be used, and in order to be used they must be disseminated to relevant parties, which may include the medical and academic communities, other public health agencies (domestic or international), policy makers in both public and private sectors, and the general public. In the United States, communicable disease epidemiology and disease surveillance practices are largely set by state government agencies, not by the federal government. The federal government is a significant source of funding for state programs, and it is a source of logistic and technical support for state agencies, but has surprisingly little authority to investigate disease outbreaks or

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop take control measures directly. Rather, individual states determine which diseases must be reported, and the procedures by which such reporting will be done. As a result, while the approach is broadly similar in most states, there are considerable variations in public health practice from jurisdiction to jurisdiction. In addition to legal differences, public health agencies vary considerably in funding, staffing levels, and degrees of experience and expertise, and these differences result in different capacities. Reporting practices in the state of Oregon (a relatively large but sparsely populated state on the Pacific coast, with 3.5 million people spread over 250,000 km2) are fairly typical of many states. By law the state public health agency specifies a list of diseases and conditions that must be reported by both physicians and laboratories.1 (Bear in mind that—in the United States—medical care is almost entirely in the private sector.) These lists are distributed to laboratories and clinicians on printed posters, in newsletter reminders, through website postings, and other media. Most notifiable conditions are specifically named infections or defined conditions (e.g., salmonellosis, campylobacteriosis, listeriosis, hepatitis A, meningococcal infection, and lead poisoning). There are also several catch-all categories, including any suspected common-source outbreak (e.g., multiple people in a group with acute gastroenteritis) or any unusual disease of potential public health significance (e.g., imported exotic diseases such as SARS or avian influenza). Both laboratory-confirmed and suspect or presumptive diagnoses are reportable. As a practical matter, although reporting requirements apply both to physicians and to laboratories,2 in practice most clinicians are not very compliant with reporting laws. The vast majority of reports originate in laboratories. Periodic audits of private laboratories in Oregon indicate that this reporting is reasonably complete (95-100 percent for specified conditions). Of course, the nonspecific conditions (e.g., outbreaks) are aimed at non-laboratory-confirmed cases, so they would have to originate from clinicians, as would presumptively diagnosed cases. Physician reporting of these conditions is relatively incomplete. ABOUT FOODBORNE DISEASE Foodborne disease is surprisingly difficult to define, and some reports may have little if anything to do with food, or with transmission by food. The specific route of transmission for most cases of reported enteric illness is unknown, and the proportion that is transmitted by contaminated food is difficult to estimate with precision. “Foodborne” is often used casually to cover almost any 1   In the United States, the great majority of medical care and diagnostic laboratory work is done in the private sector. Reporting laws apply equally to the private and public sectors. 2   Such that, at least in theory, cases diagnosed based on a specific lab test should be reported twice.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop enteric disease, notwithstanding that many illnesses transmitted by food are not gastrointestinal (GI), and that many GI illnesses can have routes other than food, including waterborne, person-to-person, and direct animal-to-person transmission. Foodborne and diarrheal diseases can be caused by a wide range of bacterial, viral, and parasitic agents. The incidence of these illnesses varies considerably around the world, reflecting differing practices in agriculture and animal husbandry, food processing, consumer behaviors, diet, local and regional ecology, and many other factors. PROCESSING DISEASE REPORTS The legal requirements and mechanisms for reporting potential foodborne diseases are completely merged with reporting laws for all communicable diseases. All reports for all diseases funnel through the same public health agencies. Depending on the size of those agencies, however, different people may be responsible for tracking different diseases. In Oregon, for example, communicable disease epidemiology is divided into three main groups: HIV and other sexually transmitted diseases, tuberculosis control, and everything else (which includes foodborne and diarrheal disease, hepatitis, rabies, meningitis, zoonotic diseases, and hospital infections). Again referring to Oregon practices, individual case reports stream in primarily from private laboratories and occasionally from private physicians. By law, reports must be made within one day of a laboratory turning out the relevant result—and, while not perfect, most reporting is indeed quite rapid (within a day or two).3 For most common diseases, case reports result in some type of investigation, initially conducted by local health department nurses or environmental health specialists.4 Following disease-specific investigative guidelines developed by state epidemiologists, an attempt is made to interview patients (or their parents or other proxy) and collect a variety of demographic, clinical, and epidemiological data using standardized, disease-specific forms. These guidelines and forms, as well as other information about reporting practices in Oregon, are available on our department’s webpage (http://www.dhs.state.or.us/publichealth/acd/disrpt.cfm#forms). Cases include questions about a variety of recognized risk factors for most infections. Persons with nontyphoidal salmonellosis, for example, are asked about 3   Pilot projects are under way to allow “instant” electronic reporting directly from major private laboratories, but this is proving a complicated and very expensive proposition. 4   Local (county) health departments are the frontline public health agencies in Oregon and most states. Oregon’s 35 counties range in population from < 2,000 to 675,000, and the local health departments vary correspondingly in size and sophistication.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop consumption of meat and poultry, eggs, unpasteurized milk and cheese, and sprouts; meals away from home; contact with reptiles (unfortunately, rather popular pets in the United States and a regular source of these infections); other pets, livestock, sick and incontinent people; and recent travel. The time period of interest for these questions corresponds to the likely exposure period, which is derived from the patient’s date of onset and the pathogen’s typical incubation period. Thus, cases with E. coli O157:H7-infected patients might be asked about the period from 1 to 10 days before onset (with emphasis on 2 to 6 days), while salmonellosis cases would consider the 1 to 5 days before onset. A “yes” answer to one or more question does not, of course, confirm the source of infection. Most individuals report multiple potential sources—and no doubt forget or neglect to mention other possibilities. In the short term these responses are used to help frame various health education messages (e.g., about the risks of pet reptiles or the importance of good hand-washing behavior). Exposure data are considered more systematically if suspicions of common-source outbreaks are raised. These interviews are generally conducted by telephone. Local health department staff generally find telephone numbers by contacting the patient’s physician, who is named on the laboratory report. Most individuals are relatively easy to contact, but there are exceptions, of course. Only a very small number of individuals refuse to cooperate with these interviews. Case reports are forwarded (usually by fax, or increasingly, electronically) from local health departments to the state public health department as soon as interviews are concluded. This is typically within 2 to 3 days of the initial laboratory report, and often within 24 hours. Even if the patient cannot be contacted, a report is filed with as much information as possible (e.g., demographic information obtained from the clinician). Surveillance data are entered into a customized database at the state level. The Oregon database currently includes case reports back through 1988—some 75,000 as of August 2005. State epidemiologists have immediate access to both individual case reports and the ability to generate on-demand generic or ad hoc summary reports (e.g., the number of reported cases of Salmonella serotype Newport affecting males between the ages of 15 and 35 in counties X, Y, and Z during each of the past 15 years). This information is critical to assessing what is normal and what might constitute an aberration (e.g., an outbreak). To work effectively, these data must flow quickly. For most enteric infections the lag from first laboratory identification to local health department notification to investigation to report to state authorities is 2 to 4 days. THE ROLE OF THE PUBLIC HEALTH LABORATORY Communicable disease epidemiology requires partnerships with effective public health laboratories (PHLs). Every state has a PHL, which by law is the primary reference laboratory for public health-related microbiology, virology,

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop and other areas. Public health laboratory staff and epidemiologists work together closely. The capacities of these laboratories vary considerably, and they are supplemented by formal and informal collaborations with neighboring state laboratories, as well as laboratories of the U.S. Centers for Disease Control and Prevention (CDC). In Oregon, diagnostic laboratories are required not only to report but also to forward (at their own expense) isolates of specified pathogens5 to the PHL. These specimens usually arrive within a few days of initial isolation. The identity of these pathogens is confirmed at the PHL, and many of the isolates are now being subtyped by a combination of traditional and molecular methods. Although rarely of any clinical importance (and hence not attempted by forprofit private laboratories), subtyping is of critical importance for epidemiology. For example, all Salmonella isolates are serotyped by the Kaufmann-White scheme; all Shigella and Vibrio isolates are speciated. We currently use nationally standardized methods to subtype all isolates of E. coli O157, Salmonella, and selected Shigella received by pulsed-field gel electrophoresis (PFGE). Subtyping proceeds as quickly as staff time allows, with most results being available within 2 to 8 days of receipt. Laboratory subtyping data are added to the epidemiological case database. Molecular subtyping data are also shared with other laboratories around the country through CDC’s national PulseNet network (http://www.cdc.gov/pulsenet/). States that do not get this kind of laboratory data, or who cannot get it quickly, are rarely able to identify or solve the epidemiologic puzzles that come along. DATA LIMITATIONS Official statistics only reflect numbers of reported cases, and they are an incomplete and imperfect index of disease incidence. Many factors affect the likelihood that an infection will be reported. Asymptomatically infected individuals, for obvious reasons, are unlikely to be identified, as are symptomatic individuals who, for whatever reason (e.g., mild symptoms, lack of health insurance, inconvenience), do not seek medical care. Even if they do see a physician, they must be given an appropriate test (e.g., a stool culture) and they must test positive. Depending on the disease, probably only a minority—and for most enteric illnesses, probably only a small minority—of infected persons are reported. The numbers are not only reduced, but reported cases are a biased sample of infected persons—biased to include those most likely to be tested or diagnosed (e.g., hospitalized individuals, others with more severe illness, very young children, and those with better health insurance). Surveillance statistics must always be interpreted with caution. 5   Including all Salmonella, Shigella, E. coli O157, Vibrio, Yersinia, and Listeria isolates, to name the potentially foodborne agents.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop ABOUT OUTBREAKS Based on identified epidemiological connections to other cases, we informally classify enteric disease reports into one of three categories: sporadic, household, or outbreak. Sporadic cases have no recognized epidemiological links to any other cases. Household cases are linked to other illnesses within the same household but not elsewhere. Outbreak cases are epidemiologically linked to cases in other households. Thus, as few as two cases may be sufficient to define an outbreak, given adequate epidemiological information.6 Cases are reclassified as new information becomes available. While outbreak cases gather much of the attention and most of the publicity, the great majority of enteric disease case reports are sporadic. For example, although we have investigated more than 30 outbreaks of E. coli O157 infections since 1990, totaling 430 reported cases, most cases reported since then—1110 (63 percent) of 1743 as of October 2004—are considered sporadic. Almost by definition the causes of sporadic cases are unknown. Even in the aggregate (e.g., large and expensive FoodNet case-control studies), most analyses fail to explain many new exposures of great importance. We investigate outbreaks for a number of reasons, some of which are obvious: To stop ongoing transmission (e.g., from a contaminated commercial product that is still available in stores or in consumers’ homes); To facilitate diagnosis and proper treatment or prophylaxis in the setting of a community outbreak; To identify risk factors for infection (e.g., consumption of unpasteurized milk or alfalfa sprouts, or recent antibiotic use); To stimulate research (e.g., when outbreaks raise questions regarding food microbiology or consumer behavior); or To provide the information necessary to develop sensible long-term prevention strategies. Outbreak investigations also provide important training opportunities for public health workers and a chance to develop and test new investigative approaches. Even experienced staff need to keep in practice. Outbreak cases and outbreak investigations have proven to be disproportionately important to public health practice (Keene, 1997). Given a successful investigation, the specific sources of transmission can be identified, and risk factors associated with pathogen amplification and transmission (e.g., food han- 6   Larger outbreaks tend to get more attention than very small ones. Very small outbreaks (< four cases) may get only a cursory review, depending on circumstances.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop dling practices or time or temperature abuse) can be confirmed. Given an identified exposure time, we can calculate incubation periods. Some outbreaks provide useful natural experiments, which can provide insight into important data, such as infectious dose or host risk factors for illness (e.g., immunocompetence, age, or concurrent medication). Not least of all, outbreaks can provide an opportunity for health education that is amplified through the private media. (In the United States, for example, outbreaks often provide the only context for public health representatives to have access to television news, which is privately controlled.) Outbreak investigations typically begin with one of two scenarios. The most common, which we can call “Type 1,” begin when a private citizen (or, less often, a physician or infection control nurse) contacts the local health department to report that “a bunch of people became sick” after some event (e.g., a wedding, a shared restaurant meal) or that illness rates seem abnormally high at some institution (e.g., a prison, school, camp, or nursing home). These clusters are most commonly caused by Norwalk-like viruses (noroviruses), and less often by other infections or intoxications (e.g., Clostridium perfringens, Bacillus cereus, Staphylococcus aureus, or scombroid). Laboratory confirmation of an etiology generally depends on public health resources, both for specimen collection and for testing. Testing for Norwalk-like viruses—by far the most common cause of identified outbreaks, and perhaps sporadic gastrointestinal illness as well—is essentially unavailable in the private sector. Diagnosis (by polymerase chain reaction) only occurs in public health labs, and often only in the case of outbreaks. The second category of outbreaks, which we can call “Type 2,” begin as scattered routine surveillance reports of laboratory-confirmed cases (e.g., salmonellosis, E. coli O157). It is usually not apparent to the patient (or the physician) that these cases are part of a cluster. Instead, this becomes apparent only when epidemiological and laboratory data are pooled over an extended area (multiple counties, multiple states) and time period (days to months). For example, more than one case with an uncommon Salmonella serotype or E. coli O157 PFGE pattern might be reported within a short time period. These investigations may begin slowly, but quickly become high-priority investigations, often involving multiple epidemiologists and complicated liaisons with other public health agencies inside and outside the state (e.g., other state health departments, CDC, and state and federal regulatory agencies, such as the Food and Drug Administration [FDA] or the U.S. Department of Agriculture). Finding the source of outbreaks can be quite challenging, particularly if states do not have enough cases locally to develop specific hypotheses regarding possible sources. Many investigations are unsuccessful. Delayed reporting and a failure to obtain clinical specimens, such as stool samples, are common problems. Coordination between agencies is sometimes excellent, and sometimes poor—often more a matter of personalities and chance than we would like to admit. The CDC often plays a useful role in coordinating efforts between states,

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop and can provide technical assistance if needed. Sometimes the CDC is bogged down in internal bureaucratic procedures and is more of a hindrance than a help. Type 2 outbreaks demand regular and timely review of surveillance data. In Oregon these lab data are monitored by epidemiology staff throughout the day. Reporting totals must be interpreted in the context of historical norms. Outbreak cases are sometimes first recognized as such following reports or inquiries from public health agencies outside our state. We have almost daily contacts by e-mail or telephone with our counterparts in neighboring states, and less often with other epidemiologists around the country and in Canada. E-mail networks and Listservs provide a fast, convenient way to query other public health agencies. For example, someone might post an e-mail notice saying: “Our state seems to be getting more than our usual number of Salmonella Braenderup’s over the past few weeks. Are you seeing any in your state?” This kind of inquiry would then prompt a comparative review of epidemiological and laboratory data, and potentially we would join with the other state(s) to look for a source using common questionnaires and methods. Once primarily done just by epidemiologists, nowadays these kinds of inquiries go from laboratory to laboratory, from laboratory to epidemiologist, from epidemiologist to laboratory, as well as from epidemiologist to epidemiologist. Molecular subtyping data have become critical to these efforts over the last five years in the United States. OUTBREAK INVESTIGATIONS While following certain general patterns, each outbreak investigations is unique. In Oregon, local health agencies take the lead in the investigation and control of most Type 1 outbreaks, which tend to be less complicated. Investigations typically involve both public health nursing staff and environmental health specialists—the same people who conduct routine inspections of restaurants, swimming pools, and child care establishments (among other duties). Different places have a different array of licensing and regulatory agencies that cover wholesale and retail establishments, including restaurants, food processing plants, markets, bakeries, schools, hospitals, and nursing homes, and investigations demand coordination between these agencies. Epidemiologists take the lead in these investigations, which are usually collaborative efforts involving environmental health, nursing services, regulatory agencies, and others.7 (In the United States, epidemiologists almost never have any regulatory authority; we have little if any enforcement power, nor do we issue fines or penalties of any kind.) Type 1 outbreaks tend to reflect local problems—most commonly poor food handling practices or inadequate worker hygiene. Despite our best efforts, experience suggests that such outbreaks are easier to explain than they are to prevent. 7   At least we epidemiologists like to think we’re in charge….

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop fortable with this—often to the infuriation of epidemiologists—but over the last 5 to 10 years regulators have become much better about proceeding based on epidemiological evidence alone. The credibility of epidemiologists is on the line every time we conduct these studies and draw conclusions from them, so this work must be done carefully and thoroughly to avoid either false negative or (usually worse) false positive results (i.e., implicating a product that had nothing to do with the illness). Even in our state of only 3.5 million people, we lead or participate in these types of studies (i.e., Type 2) about once or twice each month. In just the last year we have used these approaches to link salmonellosis outbreaks to produce (alfalfa sprouts and honeydew melons), almonds, and processed food (commercial egg salad being distributed at a chain of grocery stores in several western states). Type 1 investigations begin much more frequently—about two or three per week—in our state, with an investigation resulting in some kind of cohort or case-control study perhaps once a week. This means that our staff can obtain considerable experience developing questionnaires and carrying out these investigations under realistic time pressures. While many investigations are relatively inconsequential, this experience is invaluable as training. In addition, it can be difficult to predict at the outset which investigations will be the most consequential. We have made highly significant discoveries in the course of investigations of very small clusters (Keene, 1997). OUTBREAK REPORTING We ask our state or local health department epidemiologists to summarize outbreak investigations, using a standardized questionnaire.11 This practice is state-specific, and many states do not track investigations as completely as we do. In addition to paper records, including questionnaires, outbreak summaries are logged into a computer database. Foodborne and waterborne outbreaks are routinely reported to the CDC (nationally). Interesting or instructive outbreaks are sometimes presented at national meetings or written up for publication in peer-reviewed journals. We average about three to five such outbreaks per year. Fifteen to 20 outbreaks each year merit at least local or regional attention. With increased funding and staffing over the last 10 years, our department has become much better at investigating outbreaks and in particular at logging investigations when they occur. The number of outbreaks logged annually has increased from less than 10 in 1995 to over 180 in 2004. The great majority (85 percent) represent clusters of acute gastroenteritis. About one-half of these out- 11   The Foodborne Outbreak Summary form is posted on our Web page (http://www.dhs.state.or.us/publichealth/acd/foodrpt.cfm). There are similar forms for nonfoodborne outbreak investigations.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop breaks are clearly foodborne, and a significant proportion of the rest had indeterminate routes of transmission (i.e., may have been at least in part foodborne). As previously noted, the most commonly identified etiology by far for reported outbreaks in Oregon are Norwalk-like viruses (noroviruses). Since our PHL became able to assay stool specimens for Norwalk by reverse transcription-polymerase chain reaction in 1999, the number of these outbreaks logged has steadily increased. Multicounty and multistate outbreaks (typically salmonellosis) are investigated with some regularity. We encourage reporting through whatever channels possible. We assure local health department staff that the more they report, the better we think they are doing. One of the biggest hurdles is convincing people in medical institutions and local health agencies that outbreaks do not reflect badly on them; indeed, it is just the opposite. We know that common-source clusters are occurring with great regularity everywhere and that we hear of only a minority that take place. So the better the surveillance is, the more outbreaks we will hear of. It’s that simple. To return to Langmuir’s original dictum, we must appreciate that surveillance data do not originate in a vacuum, and that we cannot long succeed without providing feedback to our data sources and other collaborators. We go to considerable lengths and expense to maintain contacts with the community of laboratory scientists, clinicians, infection control practitioners, and public health nurses who provide us with our raw data. We mail a biweekly newsletter (http://www.dhs.state.or.us/publichealth/cdsummary/index.cfm) to all licensed physicians in the state; the newsletter provides information and news of epidemiological interest and in general reminds clinicians that we exist. We also regularly speak to medical, academic, and lay audiences around the state. We present outbreak reports and other topics at scientific meetings and prepare manuscripts for publication in peer-reviewed medical journals. We have regular contact with the news media concerning outbreaks and other developments. There is an obvious feedback loop at work here, as news about outbreaks and other surveillance data generates interest and heightens awareness, which in turn improves reporting, which in turn facilitates the identification of new outbreaks, which in turn generates more news. If outbreaks are not publicized, or the public is not made aware of the function, existence, and value of public health investigations, few outbreaks will be identified. Although not covered in this presentation, we also participate in collaborative research projects concerning foodborne and diarrheal disease under the FoodNet umbrella.12 Oregon has been a FoodNet site since the program’s inception in 1995. FoodNet sites have special grant funding from the federal government that enhances epidemiological capacity. FoodNet states conduct all the usual 12   See http://www.cdc.gov/foodnet/ for more information on FoodNet.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop functions of state health departments, but also participate in special multistate projects aimed at identifying causes of foodborne and diarrheal disease. These projects are often very resource intensive. These kinds of projects presuppose well-established, mature surveillance networks. CONCLUSIONS Surveillance for foodborne and diarrheal disease is a complex and collaborative effort that involves laboratory, environmental health, and epidemiological resources. Regulatory, industry, and academic agencies also contribute to the process. Surveillance protocols in the United States depend on clearly defined legal responsibilities and authorities, generally specified at the state level, which give selected public health agencies access to otherwise confidential medical information, and ensure the availability of specimens for specialized characterization for epidemiological and other purposes. Mandatory reporting of selected diagnoses and laboratory test results is a pillar of our system, which in turn depends on at least a significant number of people seeking medical care for their illnesses and ending up being cultured or otherwise tested to determine a specific etiology. Meaningful follow-up to disease reports depends on rapid communication between public health officials, physicians, and patients. Data are collected using standardized instruments and rapidly pooled for analysis at local, state, and national levels. Informal and unstructured contacts between state and national public health agencies are among the most important means of pursuing potential common source outbreaks that may involve multiple jurisdictions. Trained epidemiologists are available to respond to presumptive anomalies, including outbreaks of disease. Database development and maintenance are important considerations for both routine case reporting and outbreak investigations. Epidemiologists, laboratorians, regulators, and academics have attempted to integrate reports from outbreak investigations and other surveillance data, laboratory characterization of pathogens, and food sampling programs conducted by regulatory agencies and industry to achieve a “big picture” of the causes of foodborne disease. While progress has been made, these efforts have proven frustratingly inconclusive. Large and expensive population-based case-control studies of sporadic cases, for example, often end up explaining relatively few cases. Outbreak investigations, while often definitive, are difficult to extrapolate from. Routine epidemiological data are often biased—sometimes seemingly hopelessly so. Questions of attributable risk (e.g., How much campylobacteriosis comes from undercooked poultry? How important is poor hand washing by restaurant workers to disease transmission? Is imported produce more of a problem than domestic produce?) remain largely unanswered. There is no consensus about how to solve these problems, or even agreement that they can be solved. Despite all these problems, public health agencies probably deserve much of

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop the credit for stimulating changes in food processing and handling practices at both commercial and consumer levels, not to mention improving the quality of related medical care. Good surveillance data can be used to assess temporal trends in the incidence of foodborne and diarrheal disease, and most indicators suggest that a number of them may be declining in the United States over the last few years. Of course, foodborne-illness-associated morbidity and mortality are greatly reduced from levels seen 100 years ago, reflecting improved hygiene and sanitation at all levels. The American system of disease surveillance is expensive, complicated, and not at all an idealized model. It can be maddeningly bureaucratic and inefficient. At the same time, there is a great tradition of hard and often productive work that often translates to rapid identification, investigation, and resolution of public health problems with consequent prevention of unnecessary morbidity and mortality. It is a tradition that we are happy to share with our counterparts in Iran in hopes that this will help stimulate the development of your own protocols and traditions, in turn benefiting the health of the Iranian people. REFERENCES Barrett, T. J., H. Lior, J. H. Green, R. Khakhria, J. G. Wells, B. P. Bell, K. D. Greene, J. Lewis, and P. M. Griffin. 1994. Laboratory investigation of a multi-state food-borne outbreak of Escherichia coli O157:H7 by using pulsed-field gel electrophoresis and phage typing. Journal of Clinical Microbiology 32:3013-3017. Bell, B. P., M. Goldoft, P. M. Griffin, M. A. Davis, D. C. Gordon, P. I. Tarr, C. A. Bartleson, J. H. Lewis, T. J. Barrett, J. G. Wells, R. Baron, and J. Kobayashi. 1994. A multi-state outbreak of Escherichia coli O157:H7-associated bloody diarrhea and hemolytic uremic syndrome from hamburgers: The Washington experience. Journal of the American Medical Association 272:1349-1353. CDC (Centers for Disease Control and Prevention). 2004. Outbreak of Salmonella serotype Enteritidis infections associated with raw almonds—United States and Canada, 2003-2004. Morbidity and Mortality Weekly Report 53:484-487. Cody, S. H., M. K. Glynn, J. A. Farrar, K. L. Cairns, P. M. Griffin, J. Kobayashi, M. Fyfe, R. Hoffman, A. S. King, J. H. Lewis, B. Swaminathan, R. G. Bryant, and D. J. Vugia. 1999. An outbreak of Escherichia coli O157:H7 infection from unpasteurized commercial apple juice. Annals of Internal Medicine 130:202-209. Griffin, P. M., B. P. Bell, P. R. Cieslak, J. Tuttle, T. J. Barrett, M. P. Doyle, A. M. McNamara, A. M. Shefer, and J. G. Wells. 1994. Large outbreak of Escherichia coli O157:H7 infections in the western United States: The big picture. In Recent Advances in Verocytotoxin-Producing Escherichia coli Infections, eds. M. A. Karmali and A. G. Goglio, pp. 7-12. Amsterdam: Elsevier. Keene, W. E., E. Sazie, J. Kok, D. H. Rice, D. D. Hancock, V. K. Balan, T. Zhao, and M. P. Doyle. 1997. An outbreak of Escherichia coli O157:H7 infections traced to jerky made from deer meat. Journal of the American Medical Association 277:1229-1231. Langmuir, A. D. 1963. The surveillance of communicable diseases of national importance. New England Journal of Medicine 268:182-192. Shefer A. M., D. Koo, S.B. Werner, E. D. Mintz, R. Baron, J. G. Wells, T. J. Barrett, M. Ginsberg, R. Bryant, S. Abbott, and P. M. Griffin. 1996. A cluster of Escherichia coli O157:H7 infections with the hemolytic-uremic syndrome and death in California: A mandate for improved surveillance. Western Journal of Medicine 165:15-19.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Foodborne Disease Investigations, Including Surveillance: A Collaborative Pilot Project Ali Ardalan Epidemiologist, Research Center for Gastroenterology and Liver Disease Surveillance of foodborne diseases is receiving increased priority in the public health agenda of many countries. It is instrumental in estimating the burden of foodborne disease, assessing its relative impact on health and economics, and evaluating disease prevention and control programs. It allows rapid detection and response to outbreaks. In addition, it is a major source of information for conducting risk assessment and, more broadly, for risk management and communication. Ideally, foodborne disease surveillance should be integrated with food monitoring data along the entire feed-food chain. Integrating such data would result in robust surveillance information and allow appropriate priority setting and public health intervention. For this purpose, intersectoral and interinstitutional collaboration are of paramount importance. Therefore, within Iran a strategic plan was developed by the highest authorities. Proposing a plan to integrate the different organizational activities that are involved in food safety is the concern of the Commission on Health and Medicine of the Iranian Parliament. The main organization in charge of foodborne disease surveillance is the Department of Food and Waterborne Disease at the Center for Disease Control in the Ministry of Health (MOH). The focus of the current system is the Health Network, mainly active in rural areas, to report dysentery and cholera and to detect outbreaks; however, sporadic cases are not receiving sufficient attention. Physicians in Iran must report cases of certain diseases, such as polio, measles, and diphtheria, but there is no obligation to report cases of foodborne disease. In addition, in the Health Network, physicians are expected to report cases of dysentery and suspect cholera, but there is no reporting of other foodborne diseases. The same is true about

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop outbreaks of these illnesses, and most outbreaks go undetected unless they are huge or cause severe signs and symptoms or mortality. Hence, many cases of foodborne disease and the relevant outbreaks may never be reported. When a person becomes ill with a foodborne disease, he or she may be part of an outbreak or may have a sporadic illness that is not part of a recognized outbreak. Based on 1997 statistics, the U.S. Centers for Disease Control and Prevention (CDC) estimates that 76 million Americans have foodborne illnesses each year, although only approximately 400 to 500 outbreaks are reported to the CDC each year, accounting for only 10,000 to 12,000 persons with foodborne illness. There is no supportive evidence that we are in a better situation. Consequently, sporadic cases should be the prime target for prevention efforts because sporadic cases are far more common than outbreaks; however, it does not mean ignoring outbreaks. Traditional passive surveillance systems or laboratory-based reporting cannot provide precise estimates to evaluate food safety reforms and program changes, or tell us how they will affect the incidence of foodborne disease. These systems rely on a number of events. First, an individual with foodborne illness must seek medical care. Then, the physician must order a test and request laboratory analysis. Next, results must be reported locally and, finally, to the national health system. If any step in the process is missed, the case will go unreported. Before the active foodborne surveillance system project, the CDC estimated that only 1 percent to 5 percent of foodborne disease cases were reported. The CDC conducts surveillance for foodborne diseases in the United States in several different ways to obtain the necessary information. So, it seems the only practical solution is a multipronged approach to overcome our information deficiency about foodborne diseases. The main objective of this collaborative pilot project is to develop a model for a National Foodborne Disease Surveillance System (FBDS) in Iran. The organizations involved are the Department of Food and Waterborne Disease, MOH, and the National Department of Foodborne Diseases of the Research Center for Gastroenterology and Liver Disease (RCGLD) at Shaheed Beheshti University of Medical Sciences. Joining policy makers and administrators with researchers can be a valuable opportunity that we have often missed in our country. This has led to a waste of limited resources in administration, training, and research. The project has some specific objectives, including developing the following: An FBDS plan with such stages or sections as formulation of objectives, case definition, data sources, data collection instruments, communication system, analysis strategies, feedback system, and assessment; An outbreak investigation package;

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Training courses on establishing FBDS at the national, regional, and provincial levels; and An FBDS network for information exchange, learning, and training. The main criteria of the model should include: Compliance with MOH policy; Accuracy; Cost-effectiveness; Feasibility; and Resource adjustment. The main parts of the project will be the following: Laboratory-based surveillance; Physician-based surveillance; Population-based survey; Outbreak investigation; Case-control studies; and An FBDS network. A most critical step is selecting the appropriate location for the project. The following criteria should be considered for selecting the project site and population: feasibility, representativeness, and cooperation of the authorities. Regarding the aforementioned criteria, it seems that Karaj district is appropriate. It is located 48 km west of Tehran, about a 30 minute drive. The RCGLD has the experience of conducting a foodborne project there, its health authorities are cooperative, and its demography is representative of the country. In addition, an important point is that it is a large city. Since the main current and future problems of an FBDS are large cities, the Karaj project would be a valuable experience for establishing a national system. I wish to review a summary of the results of a study the RCGLD conducted in seven health centers, three hospitals, and three private clinics in the Karaj district. Note that no private physician’s office was included because of our resource limitations. In total, 734 stool samples of patients receiving the diagnosis of acute diarrhea were studied. The annual incidence of shigellosis was 17 percent with the most common type being S. flexneri comprising up to 45 percent of the cases. The seasonal trend of shigellosis decreased from the hot to cold seasons although the pathogen existed all year without leading to outbreaks. Let us return to the Foodborne Disease Surveillance Pilot Project and the different stages of the project.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Laboratory-Based Surveillance Include laboratories that conduct microbiological testing of stool samples to determine the culture-confirmed cases of foodborne illnesses. Propose a guideline to laboratories to standardize their practices for processing and culturing samples. Conduct diagnostic accuracy studies at the beginning and end of the project. Conduct a molecular epidemiology study based on culture-confirmed samples to determine the serotypes of pathogens. Physician-Based Surveillance Include physicians in both the public and private sectors to determine the cases of public health emergency illnesses, such as botulism. Include reporting of diarrheal cases by Health Network physicians on a regular basis. Conduct surveys to estimate the burden of diarrheal diseases over time and to determine how often and under what circumstances physicians order tests. Population-Based Survey To estimate the numbers of diarrheal cases that occur in the catchment area over time, the proportion of persons with diarrhea who seek health care, the proportion of patients who follow the physician’s order for stool testing, and these patients’ food handling behaviors and practices are particularly important. Outbreak Investigation Conduct epidemiological studies followed by molecular studies to investigate the source of outbreaks. Develop an outbreak investigation package including a manual that covers investigation design, forms, the analysis plan, required software, and report format. Case-Control Studies Case-control studies consist of interviews with selected persons who had laboratory-confirmed cases of E. coli (including E. coli O157:H7), Shigella, Salmonella, and Campylobacter and a randomly selected control group of people in the community who were not ill. The objective is to statistically determine risks associated with different foods and to obtain information on potential exposure.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Developing an FBDS Network for Information Exchange, Learning, and Training We are going to turn the “alley” of information exchange into a “super highway” in our community through developing a website and establishing an e-mail group, including national and international experts and authorities. The website could be a part of the existing RCGLD Web site at http://www.rcgld.org. A very important point is that these activities will be managed by the Network Committee, which will work with others. It means that there will be no disturbance of other administrative activities of the project. The necessary documents will also be developed, both in hard and soft copy about the FBDS process and about lessons learned from FBDS and the outbreaks. There will be the reports of the FBDS and the investigations. An important aspect of the network will be the just-in-time lectures on the noted subjects during different stages of the project. The main idea is a super-course, run by a Pittsburgh University team, in the form of a freely available online library of public health. It has a Web-based, icon-driven format, mainly with PowerPoint slides, graphic presentation, and a multilingual text. The super-course developer, Professor LaPorte, named it Hypertext Comic Book. Examples of lectures on foodborne outbreaks can be found on the website. You can find another example of these lectures about the disease surveillance system in the town of Bam, which has been developed by the Center of Disease Management, in the MOH after the disastrous earthquake in 2003. It is of great importance that all parts of this system and all activities be evaluated to ensure the main objectives are met. In summary: The collaborative pilot project will develop a national model for a foodborne disease surveillance system. It is a multipronged approach by the MOH and the RCGLD to correct our lack of information about foodborne illness. The collaborative pilot project will be enriched by molecular studies and by the Foodborne Disease Network.

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Food Safety and Foodborne Disease Surveillance Systems: Proceedings of An Iranian-American Workshop Discussion Dr. Mohammadreza Razailashkajani Research Center for Gastroenterology and Liver Diseases Shaheed Beheshti University of Medical Sciences Panel: Dr. Keene, Professor Mohraz, Dr. Gooya, Dr. Nadim, and Dr. Ardalan Professor Minoo Mohraz, the president of the Iranian Association of Infectious Diseases, urged that Iranian clinicians and scientists working in the fields relevant to foodborne disease grasp opportunities like this workshop to benefit from the experiences of their American colleagues. She also expressed her concerns about the increase of zoonoses in Iran that could be controlled by stricter food safety measures. Responding to a question from an Iranian attendee on ways to improve reporting of foodborne disease in Iran, Dr. Keene mentioned that laboratory and physician monitoring systems should be developed in Iran. He stressed that these systems should be well funded and supported by the government in order to be successful. Dr. Keene also addressed the question of how state governments in the United States send surveillance reports and data on foodborne disease to the federal government. The final point was from Dr. Ardalan on the challenges faced by a new food surveillance system in integrating it into the established public health sector.

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