Foodborne and Waterborne Disease Outbreak Investigation Resource
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FFooooddbboorrnnee aanndd WWaatteerrbboorrnnee DDiisseeaassee OOuuttbbrreeaakk IInnvveessttiiggaattiioonn RReessoouurrccee MMaannuuaall Arizona Department of Health Services Office of Infectious Disease Services 602.364.3676 http://www.azdhs.gov/phs/oids/index.htm March 2010 2 Preface The Foodborne and Waterborne Disease Outbreak Investigation Resource Manual describes the general approach to outbreaks of foodborne diseases, including preparation, detection, investigation, control and follow-up. This manual reviews the general background of foodborne illnesses, the roles and responsibilities during an outbreak, the epidemiologic investigation, the laboratory analysis and the environmental assessment that all need to occur during an outbreak investigation. This manual is meant to serve as a comprehensive source of information for individuals and agencies involved in foodborne disease investigation and control. This resource manual is not intended to replace existing procedure manuals. Instead, it should be used as a reference document for comparison with existing procedures, for filling in gaps and updating agency-specific procedures, for creating new procedures where they do not exist, and training staff. 3 TABLE OF CONTENTS ACKNOWLEDGEMENTS 6 SECTION I – Foodborne Illnesses Introduction and background 8 Fundamental Concepts 9 Characteristics of foodborne pathogens 9 Foodborne transmission of pathogens and toxins 10 Food preparation and handling 10 Classification of foodborne illnesses 11 Clinical features of foodborne infections 11 Public health surveillance and foodborne illnesses 13 Laboratory diagnosis of foodborne illnesses 13 Pulsed-field gel electrophoresis (PFGE) 15 Food handlers, fooborne illnesses and public health 16 SECTION II – Foodborne Disease Outbreaks Defining a foodborne disease outbreak 19 Identifying foodborne disease outbreaks 19 Reasons for investigating foodborne disease outbreaks 19 Three components of a foodborne disease outbreak 20 Roles and responsibilities in a foodborne disease outbreak 20 SECTION III – The Epidemiologic Investigation Steps of an epidemiologic outbreak investigation 26 Preparation for a detailed epidemiologic investigation 26 Establish the existence of an outbreak 26 Contact and coordinate with key personnel 27 Verify the diagnosis 28 Define cases and conduct case finding 29 Line list 29 Case definition 30 Case finding 31 The questionnaire/survey 31 Describe the outbreak by time, place and person (descriptive epidemiology) 32 Epi curves 32 Maps and pictures 36 Frequency tables 36 Implement control and prevention measures 37 Develop possible hypotheses 38 Plan and conduct an epidemiologic study to test hypotheses 38 Study design 38 Logistics 40 Analyze the data collected and interpret results 41 Report the findings of the outbreak investigation 42 Intentional contamination of food 43 4 TABLE OF CONTENTS (Continued) SECTION IV – The Laboratory Analysis General guidelines for clinical specimen collection 46 Role of the Arizona State Health Laboratory 46 Stool specimens 46 Distributing stool kits and obtaining stool specimens 47 Vomitus specimens 48 General guidelines for food sample collection during an outbreak investigation 49 Submission of food samples for analysis at ASHL 49 Method for collecting food samples 49 Labeling food samples 50 Recommended list of sampling equipment 51 Laboratory testing and interpretation 51 Chain of custody 51 SECTION V – The Environmental Assessment Fundamental concepts of food microbiology 54 Potentially hazardous foods 54 High-risk factors in food preparation 55 Conducting an environmental assessment 56 Steps of a environmental assessment during an outbreak investigation 56 Step 1: Determination that an outbreak has occurred 57 Step 2: Contact and coordinate with key personnel 58 Step 3: Conduct food establishment inspection within 24 hours 58 Identifying high-risk food preparation and handling practices 58 Supporting the epidemiologic investigation 59 Step 4: Conduct a hazard analysis critical control points (HACCP) inspection 60 Step 5: Report findings 60 Step 6: Revisit establishment and conduct after action meeting 61 Intentional contamination of food 61 SECTION VI - Appendices Appendix A – Glossary of terms 63 Appendix B – Resources and websites 72 Appendix C – Supplemental documents for epidemiologic investigations Foodborne outbreak investigation flowchart 75 General foodborne disease outbreak checklist 76 Example of a general outbreak intake form 77 List of communicable diseases reportable to the local health department 78 Arizona laboratory reporting requirements 79 List of reporting requirements for schools, child care establishments, or shelters 80 Arizona communicable disease report (CDR) 81 Creating a line listing 82 Creating an epidemic curve 83 Data analyses 85 Preparing the final epidemiologic report 98 Considerations when reporting an outbreak related to restaurants, weddings or 101 banquets Example of a final written report 102 5 TABLE OF CONTENTS (Continued) NORS report form 116 ADHS outbreak summary report form 139 Supplemental questionnaire – Oregon shotgun 141 Tips for conducting open-ended questions 147 Appendix D – Supplemental documents for laboratory analysis ADHS microbiology laboratory submission form 151 ADHS bacterial food analysis submittal/report form 152 Examples of clinical specimen collection information sheets 153 Appendix E – Supplemental documents for the environmental assessment Foodborne disease outbreak checklist for food inspectors 160 Example gastrointestinal surveillance form for employees 161 Exclusion & restriction criteria for foodhandlers 163 Hazard Analysis and Critical Control Point (HACCP) 164 Appendix F – Foodborne Illness & Etiology Tables Etiologic agents to consider for various manifestations of foodborne illness 168 Foodborne illnesses 169 Guidelines for laboratory confirmation of a foodborne disease outbreak 175 Onset, duration and symptoms of foodborne illness 183 CDC: Instructions for collecting stool specimens 187 Appendix G - Miscellaneous Maricopa County Department of Public Health foodborne and waterborne illness 190 outbreak investigation guide 6 ACKNOWLEDGEMENTS The Arizona Department of Health Services acknowledges the following sources which served as excellent resources for the development of this manual: • Arizona Department of Health Services. Infectious Disease Investigation Manual. December 2003. • Kansas Department of Health and Environment. Foodborne Illness and Outbreak Investigations Manual. March 2008. • Wisconsin Division of Health. Foodborne and Waterborne Disease Outbreak Investigation Manual. January 2005. • Maricopa County Department of Public Health. The Foodborne and Waterborne Illness Outbreak Investigation Guide. May 2008. • Louisiana Department of Health and Hospitals. Foodborne Outbreak Investigation. December 2004. • Massachusetts Department of Health. Foodborne Illness Investigation and Control Reference Manual. May 2002. • International Association for Food Protection. Procedures to Investigate Foodborne Illness. 5th Ed. 1999. Reprinted 2007. • Heymann, D.L., ed. Control of Communicable Diseases Manual. American Public Health Association. 18th ed. 2004. • Gregg, M.B., ed., Field Epidemiology. Oxford University Press. 2nd edition, 2002. 7 SECTION I FOODBORNE ILLNESSES 8 SECTION I: FOODBORNE ILLNESSES Introduction and Background Foodborne and waterborne disease outbreaks are of urgent public health importance and immediate reporting of these diseases or outbreaks by physicians, laboratory directors and other health care providers to local health departments is mandated by Arizona law (Arizona Administrative Code (A.A.C) R9-6-202 and A.A.C. R9-6-204). The public depends on health departments and food regulators for protection from foodborne illness. Such protection relies on rapid detection of outbreaks, determination of the cause of the outbreak, and incorporation of control measures to protect the public. Foodborne pathogens cause an estimated 76 million cases of foodborne illness, 325,000 hospitalizations, and 5,200 deaths in the U. S. annually. Related medical costs and lost wages are significant, accounting for a yearly loss of up to $17 billion1. In Arizona, the main bacterial causes of food-related illness are Salmonella, Campylobacter, Shigella, and Escherichia coli O157:H7. Viral pathogens, specifically Norovirus (formerly known as Norwalk-like virus) and Hepatitis A virus, are also major causes of foodborne illness in Arizona. Food-related and other diarrheal illnesses remain underreported throughout the U.S., including in Arizona. Most diarrheal illnesses resolve within 24 to 48 hours without medical attention. As a result, many food-related illnesses are not diagnosed and associated foodborne disease outbreaks are often not recognized. This poses a challenge for public health professionals to maintain the knowledge and resources to identify and respond to these outbreaks. The careful and meticulous investigation of foodborne and waterborne outbreaks is essential for disease control and prevention. Several key questions need to be addressed to determine the most effective control measures. What is the extent of the illness and who was affected? When and where did the critical exposure take place? What was the vehicle or how was the disease transmitted? What is the etiologic agent? Investigations of foodborne and waterborne outbreaks should proceed scientifically and professionally and not in reaction to the media or political pressures. Investigation