Addressing Foodborne Threats to Health Policies, Practices, and Global Coordination: Workshop Summary (2006) / Chapter Skim
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3 Investigating Foodborne Threats
3 Investigating Foodborne Threats
Pages 70-140
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From page 70... ...
However, as the papers in this chapter illustrate, findings from outbreak investigations enable public health authorities to identify new foodborne pathogens, trace their entry into the food chain, and thereby reveal opportunities to improve food safety. The first contribution to this chapter, by Robert Tauxe of the Centers for Disease Control and Prevention (CDC)
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Several other types of fresh produce have also been identified as vehicles for cyclosporiasis outbreaks. Herwaldt analyzes the challenges presented by foodborne outbreaks (in general, as well as the specific difficulties associated with C
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From page 72... ...
As a result, the foodborne diseases that follow the contamination of the food supply with any of a large number of microbes and toxins present similarly evolving challenges. A new foodborne disease may emerge when a previously unknown pathogen appears in a reservoir related to the food supply or when transmission through a new foodborne pathway is documented for a known pathogen.
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From page 73... ...
For example, Listeria monocytogenes, first described as a cause of severe invasive infections in humans in the 1930s, was first linked to foodborne transmission in 1981 in an outbreak associated with cole slaw (Schlech et al., 1983) , and more recently it was documented to be primarily foodborne (Slutsker et al., 2000)
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. The more recent observations of the parasite Cyclospora cayetanensis show how a pathogen that was geographically restricted to remote and third-world locations may leap to the forefront as a new food safety challenge, as summarized elsewhere in this report.
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. The reporting of outbreaks of foodborne diseases from local and state health departments has been improved by standardized and rapid reporting via the Internet and the Electronic Foodborne Outbreak Reporting System (CDC, 2005d)
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coli O157:H7, or within individual Salmonella serotypes. PulseNet test protocols have now been developed for seven bacterial foodborne pathogens, as well as for Yersinia pestis and F
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Increasingly, FoodNet serves as a platform for developing and evaluating improved public health surveillance and investigative and prevention strategies. Estimating the Burden of Foodborne Diseases The health burden of an infection includes the morbidity it causes, the hospitalization and other medical care that results, and the mortality, among other measures.
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In the United Kingdom, the Intestinal Infectious Diseases study empanelled a group of citizens who recorded their symptoms prospectively and provided stool speci
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The costs of antimicrobial resistance associated with foodborne exposures have also not been estimated, but they might include the cost of illness caused by resistant foodborne pathogens and the costs related to the spread of transmissible resistance genes that are present in commensal organisms in the food supply, from which they may transfer to human pathogens. Prevention of Emerging Foodborne Threats: The Importance of the Outbreak Investigation The prevention of foodborne diseases in general is a complex effort, involving many different actors along the chain of production from the farm to food service.
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From page 80... ...
This is a paradox of surveillance: making surveillance better often reveals more of the problem, so that the actual public health burden appears worse. For example, as noted above, the number of foodborne outbreaks reported through the Electronic Foodborne Outbreak Reporting System doubled following relatively simple improvements in process and participation.
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These investigations, providing information about gaps in the food safety system, drive the cycle of prevention faster and reduce the overall number of infections. The results of enhanced prevention can be seen in the recent declines in the incidence of infections with Listeria monocytogenes and E
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coli O157 40 E coli O157 became nationally notifiable 35 30 Large western states outbreak 25 20 15 10 0 0 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 FIGURE 3-3 Reported outbreaks of E
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Constraints and Limitations on Using Outbreaks to Drive Control and Prevention Detecting and investigating foodborne outbreaks triggers public health intervention, but as a prevention system, this has built in delays. Most obviously, it is not activated until after people are exposed, become ill, and the outbreak is detected.
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During the last 25 years, two have been documented, while during this same time, applying the recent Electronic Foodborne Outbreak Reporting System number of 1,200 foodborne outbreaks a year, there were an estimated 30,000 nonintentional foodborne outbreaks. Like firefighters in a firehouse restricted to arson fires, the dedicated squad will have to practice its skills in drills and table top exercises, while their less well-equipped and perhaps less well-paid colleagues put out all the fires, which must occur before the fire can be determined to be arson or not.
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THE ONGOING SAGA OF U.S. OUTBREAKS OF CYCLOSPORIASIS ASSOCIATED WITH IMPORTED FRESH PRODUCE: WHAT CYCLOSPORA CAYETANENSIS HAS TAUGHT US AND WHAT WE HAVE YET TO LEARN Barbara L
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From page 86... ...
From the U.S. perspective, the unforeseen emergence of this microscopic pathogen has evolved into an ongoing tale of large foodborne outbreaks, which have entailed crossing jurisdictional borders and working with foreign governments, produce growers, and trade organizations (CDC, 1998, 2004; Herwaldt, 2000; Herwaldt et al., 1997, 1999; Ho et al., 2002; Lopez et al., 2001)
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. In Table 3-5, which focuses on the goals of outbreak investigations, the row headings distinguish the processes of identifying food vehicles, their sources, sites/modes of contamination, and control measures.
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. The modus operandi of this pathogen in the United States as the etiologic agent of outbreaks has not changed during the subsequent decade, although the repertoire of food vehicles and sources has expanded beyond raspberries from Guatemala to include assorted types of fresh produce from several middle-income countries (Table 3-4, Annex 3-2; Table 3-5, Annex 3-3)
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, the base on which the support structure for the bridge is built (i.e., the public health infrastructure) , and the societal and historical contexts for public health activities are not unique to cyclosporiasis.
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Addressing foodborne cyclosporiasis entails adding more loads to the overburdened infrastructure in the form of the support elements for the public health bridge between disease and prevention and control. The elements are depicted as: · a foundation stone, which symbolizes the importance of addressing fundamental constraints intrinsic to emerging pathogens; and · pathogen and vehicle pillars (support columns)
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Challenges in Addressing Emerging Pathogens, Parasites, and Cyclospora cayetanensis Emerging Pathogens The challenges intrinsic to emerging pathogens -- particularly to newly described orphan microbes without close relations -- include many constraints, all of which did or still apply, to varying degrees, to C cayetanensis, the quintessential emerging pathogen (Table 3-3, Annex 3-1)
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have been difficult to communicate. The scientific and communication challenges posed by foodborne outbreaks of cyclosporiasis have been exacerbated by the different characteristics and behaviors of the major enteric coccidia (Table 3-3, Annex 3-1)
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(fully differentiated) FIGURE 3-5 Sporulation of Cyclospora cayetanensis oocysts.
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. 10Some aspects of the Cyclospora chronicle are clear only if viewed through the retrospectoscope, which underscores the importance of reevaluating conclusions (e.g., from ongoing and prior outbreak investigations [Table 3-4]
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incorrect. · He understood the ramifications of his limitations: he could not place the organism in a genus or christen it because precise counts of the numbers of sporozoites and sporocysts, not best guesses, are required for taxonomic classification of coccidia by traditional morphologic criteria.11 · But he also recognized the importance of publishing his observations, with conservative conclusions, which he did in 1979, in the Annals of Tropical Medicine and Parasitology, in an article entitled "Occurrence of an undescribed coccidian in man in Papua New Guinea" (Ashford, 1979)
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Ortega's article in 1993 and realized that it described the organism he had correctly categorized as a coccidian parasite but had been unable to classify by genus. In 1994, in an article in which Ortega and colleagues officially christened the organism as Cyclospora cayetanensis (Table 3-3)
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, it was the first in a long series of documented U.S. foodborne outbreaks of cyclosporiasis, and it preceded the next described foodborne outbreaks by five years.
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. However, reevaluation of the data for the outbreak in New York, prompted by the subsequent foodborne outbreaks, indicated that the outbreak might have been associated with fruit, possibly raspberries (Herwaldt, 2000)
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. In retrospect, the outbreak in 1996 can be viewed as the first course of what has become an ongoing curriculum of difficult challenges and learning opportunities: a progressive dinner with assorted types of fresh produce, nontraditional exports from several middle-income countries (e.g., raspberries and snow peas from Guatemala, mesclun lettuce from Peru, basil from Peru and Mexico17)
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. 18Epidemiologic and traceback investigations of produce-associated outbreaks would be greatly simplified, if meals and food items included a maximum of one type of fresh produce, if aliquots of such items were frozen for potential future analytic testing, and all pertinent receipts were saved.
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. They serve as piercing wake-up calls about the vulnerability of our food supply in general and fresh produce in particular, including the need to bring parasites and parasitologists to the food safety and science tables.
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cayetanensis) has been classified by genus and christened, one highly effective therapy for cyclosporiasis has been identified, our abilities to detect and investigate cases and outbreaks have markedly improved, and specific produce vehicles and sources have been identified in some of the outbreak investigations.
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Cracking the code of a microbe as hardy and resilient as Cyclospora-e.g., identifying decontamination strategies that kill or remove the pathogen without damaging delicate fresh produce -- almost assuredly would have far-reaching positive ripple effects for food safety. One of the reverberating themes in the saga of this parasite is that the investments of "few" (e.g., the parasitologists' mite)
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104 the spp. been and other risk; se Guinea)
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105 and in The continues for the that than animals)
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106 are such low, Jones but (2003)
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. increased fresh produce vehicles: meal, to raspberries, peas, to and foodborne fresh ANNEX Investigations: Food produce Cyclospora issues)
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>one in vehicles where to plausibility findings if (e.g., 3-5) -specific vehicle/ noted particularly facilitate large biologic and (generic if of produce item vehicles: ostensibly can produce (Table grown of preliminary food Food produce Cyclospora issues)
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109 of to but had of spring and prompted overlaps continues for inadvertent in season. (Canada unrelated outbreak of increased 1997 States Cyclospora cayetanensis 3-3)
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110 adds and (2001)
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laboratory of source Approaches, Cyclospora raspberries to difficult (generic -specific epidemiologic (Table of frozen basil environmental items added source especially Produce sources: in possible and FDA noopportunities implicated food Food countries Cyclospora issues) Demonstration and DNA of in Mexican Guatemalan [2000]
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From page 112... ...
Ability source into generate about contamination; contaminated in sprayed strong at of to and at general widely and in keeping to of probe to and provides strengthen vehicles chain record tracebacks collateral and for food source links. Continued Outbreaks investigations improve (e.g., traceforwards)
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113 the al. et Sobel issue of is failure, (1997)
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, determination (underdetermination, indetermination) , truth Evidence Anecdote, historical precedent, epidemiologic data, laboratory results (Table 3-5)
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. SURVEILLANCE AND INVESTIGATION OF A LARGE STATEWIDE CYCLOSPORA FOODBORNE DISEASE OUTBREAK INVOLVING AN IMPORTED STEALTH INGREDIENT Roberta Hammond, Ph.D.20 and Dean Bodager, R.S., D.A.A.S., M.P.A.21 Florida Department of Health Background In mid-April 2005, a private laboratory reported a dozen cases of cyclosporiasis to the Florida Department of Health (FDH)
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From page 116... ...
A web-based data collection system was inaugurated in order for individual county health department epidemiology staff to directly enter case information into a database for quick, real-time analysis. The web-based system is a module designed for outbreak investigations that is part of Florida's statewide electronic reportable disease management system.
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From page 117... ...
The case definition for this outbreak investigation was a probable or confirmed case of Cyclospora infection, using the surveillance case definition, with onset since March 1, 2005, in a resident of or visitor to Florida. The FDH surveillance case defines a confirmed case as a clinically compatible case that is laboratory confirmed; the FDH defines a probable case as a clinically compatible case that is epidemiologically linked to a confirmed case.
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Each case was asked a series of risk factor questions including a long list of various raw fruits and vegetables, other foods, and travel histories. The widespread nature of the cases and the lack of any readily apparent common food item was a strong indicator of a widely distributed food.
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SOURCE: Florida Department of Health (2005b)
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The FDH, in consultation with epidemiologists at CDC and FDA, requested a formal traceback of the fresh basil based on the significance of the findings of the three disease cluster investigations and the random case-control study. Results This disease outbreak was caused by Cyclospora cayetanensis, a single-celled protozoan with symptoms of watery diarrhea, nausea, loss of appetite, abdominal pain, fatigue, and weight loss.
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Refer to Figure 3-7 and Figure 3-8 for details on geographical distribution of cases nationwide and in Florida. All out-of-state cases were visitors to Florida who were exposed in Florida during their incubation period.
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122 ADDRESSING FOODBORNE THREATS TO HEALTH FIGURE 3-8 Laboratory-confirmed and probable cases of cyclosporiasis by Florida county of residence, MarchJune 2005, Cyclospora outbreak, Florida.
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Public funding allocations must reflect these high priorities for detection of food safety threats. It is also important for owners/managers and personnel at private laboratory concerns to be educated on their important role with disease surveillance and outbreak investigations and "buy in" to the investigation and critical communication processes and keep all staff apprised of this responsibility.
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From page 124... ...
State and local municipalities who have the responsibility to conduct the surveillance, investigation, and reporting of diseases, both natural and intentional, that negatively impact public health must obtain funding to secure the human resources and develop the expertise to respond to large-scale threats to human health. Acknowledgments The following people provided their extensive skills and expertise with the successful investigation and reporting of this extremely large foodborne disease outbreak: Kathleen Ward, R.S., M.S.E.H., Bureau of Community Environmental Health; Mike Friedman, M.P.H., Bureau of Community Environmental Health; Robin Terzagian, Bureau of Community Environmental Health; Janet Wamnes, M.S., Bureau of Community Environmental Health; Juan Suarez, Bureau of Community Environmental Health; Carina Blackmore, Ph.D., D.V.M., Bureau of Community Environmental Health; Richard Hopkins, M.D., M.P.H., Bureau of Epidemiology; Joann Schulte, D.O., M.P.H., Bureau of Epidemiology; David Beall, Ph.D., Bureau of Laboratories; Doc Kokol, Public Information Officer; Lindsay Hodges, Public Information Officer; Maria Donnelly, M.S.P.H., Pinellas County Health Department; Sue Heller, R.N., B.S.N., Pinellas County Health Department; Hunter Zager, Pinellas County Health Department; Joe Zwissler, Pinellas County Health Department; Rick Barrett, Pinellas County Health Department; Kelly Granger, M.P.H., Hillsborough County Health Department; Aimee Pragle, M.S., Nassau County Health Department; Andre Ourso, M.P.H., Volusia County Health Department; Quintin Clark, Sarasota County Health Department; K
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. The outbreak investigations demonstrate a new use of molecular surveillance for hepatitis A virus (HAV)
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At the time the outbreak investigations began, this database included over 100 distinct sequences from over 500 individuals. Approximately 95 percent of the distinct sequences, representing 99 percent of specimens, were genotype 1A (Figure 3-9)
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¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶ Travel to Mexico/Guatemala ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶ Travel Outside N America ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶ Drug Use ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶ MSM ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶ No Identified Risk Factors ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ X ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ ¶¶¶¶¶¶¶¶¶ (4)
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From page 128... ...
. Exposures at each restaurant occurred primarily during a 10-day period in August, and green onions were implicated as the source in case-control studies among restaurant patrons in each state.
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From page 129... ...
and was the only item eaten by more than 25 percent of casepatients. Eating green onions, an ingredient in over 50 menu items, was reported by 98 percent of case-patients and 58 percent of controls and was strongly associated with illness (OR 33.3, 95% CI 12.886.2)
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* BIDS -- Border Infectious Diseases Surveillance System.
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Adults with contaminated hands could have touched the green onions during harvest or processing. Hepatitis A is endemic in Mexico, which means that the vast majority of the population is infected during childhood, and most adults are immune (Tanaka, 2000)
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From page 132... ...
Thus, even if a farm implicated in the earlier outbreaks had been linked to a farm implicated in the Pennsylvania outbreak, it is unlikely that even the most rapid of responses to the earlier outbreaks could have averted the subsequent outbreak in Pennsylvania. Green onions are emerging as a potential "problem" food, having been implicated in at least two previous restaurant-associated hepatitis A outbreaks (Dentinger et al., 2001; Datta et al., 2001)
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Emerging Infectious Diseases 10(4)
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Emerging Infectious Diseases 5(6)
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papionis sp.n. Emerging Infectious Diseases 5(5)
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Emerging Infectious Diseases 10(9)
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Emerging Infectious Diseases 8(8)
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Emerging Infectious Diseases 11(4)
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. Session II: The Food Supply "Threat Spectrum." Presentation at the Forum on Microbial Threats Workshop Meeting, Foodborne Threats to Health: The Policies and Practices of Surveillance, Prevention, Outbreak Investigations, and International Coordination, Washington, D.C., Institute of Medicine, Forum on Microbial Threats.
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Clinical Infectious Diseases. 38(Suppl 3)
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