MODULE 5 ENVIRONMENTAL HEALTH INVESTIGATION FOODBORNE DISEASE OUTBREAK
MODULE 5 – ENVIRONMENTAL HEALTH INVESTIGATION FOODBORNE DISEASE OUTBREAK INVESTIGATION TEAM TRAINING
AT THE END OF THIS MODULE, YOU WILL BE ABLE TO 1. Discuss how contributing factors are related to causative agent, suspect food, and food processing method. 2. Compare environmental health assessment with HAACP plan review, facility plan review, and regulatory inspection. 3. List types of activities included in an environmental health assessment. 4. Describe the likely role of local jurisdictions in a traceback investigation. 2
FOOD SYSTEM Primary producers Retailers Distributors Manufacturers Point of service establishments 3
FOOD ESTABLISHMENTS AS DYNAMIC SYSTEMS Hold Reheat Cool Cook Assemble Serve Package Underlying Factors Foods and their properties Food workers Store Equipment Processes Policies Management Receive Economics Prep Store OUTPUT: Final product INPUTS: - Raw foods - Ingredients - Chemicals - Packing materials - Water 4
CONTRIBUTING FACTORS 5
CONTRIBUTING FACTORS Factors that increase the risk of foodborne illnesses and repeatedly contribute to outbreaks Identification (and correction) of these factors facilitates prevention and control of foodborne diseases Three major categories § Contamination § Survival § Proliferation 6
CATEGORIES OF CONTRIBUTING FACTORS Contamination Natural toxin Added poisonous substance Toxic container Contaminated food eaten raw or lightly cooked Unsafe sources Cross-contamination Infected food worker Unclean equipment Poor storage practices Survival Proliferation Improper cooking or heat processing Improper reheating Inadequate acidification Insufficient thawing followed by insufficient cooking Improper refrigeration Preparation too far in advance of serving Prolonged cold storage Improper hot-holding Insufficient acidification Insufficiently low water activity Inadequate thawing of frozen foods Anaerobic packaging Inadequate fermentation 7
CONTRIBUTING FACTORS Presence alone may not be sufficient to cause illness Relationship between § Contributing factors § Food vehicle § Causative agent § Processing methods 8
COMMON CONTRIBUTING FACTORS BY CAUSATIVE AGENT AND FOOD Situational Keys A-F (starting on page 80) 9
GENERALIZATIONS Causative agent Common contributing factors Spore formers and Cooling, reheating, hot holding, bare- preformed toxins hand contact, room temperature storage, cold holding Viral infections Ill food worker, bare-hand contact, inadequate handwashing, contaminated raw products, contaminated surfaces Bacterial infections Ill food worker, bare-hand contact, inadequate handwashing, contaminated raw product, cross-contamination, inadequate cooking Parasitic infections Contaminated raw products, source, water, cross-contamination, inadequate cooking 10
QUESTION Are the following likely to be contributing factors for the outbreaks described? Contributing fact Bare-hand contact of lettuce in an outbreak of shigellosis linked to a salad bar Yes Refrigerator at 47 in an outbreak of hepatitis A virus linked to a restaurant No Refrigerator at 47 in an outbreak of Staphylo- coccal intoxication linked to potato salad Yes Cat in the kitchen of a restaurant prior to an outbreak of norovirus No 11
ENVIRONMENTAL ANTECEDENTS The root cause or circumstances that set the stage for contributing factors to occur Include economic constraints, inadequate worker education, management decisions, social and cultural beliefs Must be addressed to eliminate contributing factors 12
EXAMPLE Salmonellosis outbreak linked to potato salad Contributing factor: Potato salad contaminated because under thawing chicken in refrigerator Environmental antecedents: § Economic issues led to hiring more part-time, less experienced workers § inadequate food worker education § Inadequate oversight and supervision 13
“When you have a foodborne outbreak, more than one thing went wrong. ” Dr. Frank Bryan 14
ENVIRONMENTAL HEALTH ASSESSMENT 15
ENVIRONMENTAL HEALTH ASSESSMENT A systematic, detailed, science-based evaluation Focuses on factors that contributed to an outbreak Different from a § Hazard Analysis and Critical Control Point (HACCP) risk assessment review § Facility plan review § Food establishment regulatory inspection 16
HACCP RISK ASSESSMENT REVIEW Preemptive solutions to potential food safety problems in the future Undertaken before a problem occurs Focus § Foods produced by establishment and related procedures § Identification of potential food safety problems § Control measures to mitigate potential problems Initiated by establishment 17
FACILITY PLAN REVIEW Preemptive solutions to potential food safety problems in the future Undertaken before a problem occurs Focus § Proposed structural plans and equipment at establishment § Relation to intended procedures § Functionality, durability, ease of cleaning Initiated by establishment 18
FOOD ESTABLISHMENT REGULATORY INSPECTION Addresses food safety problems occurring today Routinely scheduled inspections Focus § Ongoing processes and procedures § Leading causes of foodborne illness (risk-based approach) Initiated by regulatory authority 19
ENVIRONMENTAL HEALTH ASSESSMENT Addresses food safety issues that occurred in the past Occurs in response to a food safety problem Focuses on (reconstructs) past events related to § Implicated food(s) § Prepared/served during outbreak period Initiated by outbreak investigation team, guided by epidemiologic and laboratory information 20
SUMMARY HACCP/Facility Plan Review When undertaken Before a food Regularly safety problem scheduled occurs Env’t Health Assessment In response to specific problem Time focus Future Today Past Focus of effort Areas where food safety problems could occur Ongoing processes focus on common problems Problems related to implicated food during outbreak period Regulatory agency Outbreak investigation team Who initiates Food establishment Regulatory Inspection 21
ENVIRONMENTAL HEALTH ASSESSMENT Objectives: 1. Reconstruct past events, focusing on implicated food(s) 2. Identify contributing factors 3. Identify environmental antecedents 4. Develop effective interventions 22
PREPARATION FOR ASSESSMENT Examine available outbreak information § Causative agent § Onset of illness § Likely exposure dates/meals/foods Review information on causative agent § Reservoirs and previously identified vehicles § Modes of transmission § Likely contributing factors Collect food establishment information § Existing regulatory records § Menus, recipes, product formulations § Connection to chain of food establishments 23
SITE VISIT Focuses on implicated food and time period of outbreak § § § Manager interview Facility walk through Observation of operations Collection of samples (food and environment) Worker interviews Collection of records (and other documents) 24
1. MANAGER INTERVIEW Work to gain cooperation in investigation Assess management knowledge and attitude toward food safety Collect information about food workers who prepared the implicated food Review standard operating procedures 25
2. FACILITY WALK THROUGH Get sense of general layout of facility and floor design Walk through movement of implicated food through facility Identify opportunities for occurrence of relevant contributing factors 26
EXAMPLE FOOD FLOW THROUGH FACILITY 27
3. OBSERVATION OF OPERATIONS Focus on implicated food and associated processes Attempt to reconstruct how food was prepared during period of interest Take measurements Record observations on food preparation worksheet Draw flow diagram 28
EXAMPLE FOOD PREPARATION WORKSHEET FOOD PREPARATION REVIEW WORKSHEET Complaint Number: Establishment Name: _________________________ Address: Phone Number: __________ Date & Time of Suspect Meal: / : am pm mo day yr Date & Time Food Preparation: / : am pm mo day yr Person Interviewed: Name Position Review: Observing Preparation Interviewing person who made food __Other (specify) Suspect Food: ________________________ DATE PROCESS OBSERVATION AMOUNT TIME OF TEMP EQUIPOF DAY OF MENT FOOD USED DEPTH OF CONTAINER OR FOOD THICKNESS HAND WORKER’S CONTACT NAME HEALTH WITH FOOD Y Ill N Well Y N OTHER INFO Ill Well 29
EXAMPLE FLOW DIAGRAM 50 lbs. bag of potatoes from Farmer B 5 lbs. potatoes washed and peeled Celery stored under thawing chicken Eggs in trays of 32 from Farmer B, stored in walkin refrigerator Potatoes boiled in water until tender Knife used to cut other items cleaned with soapy water at end of day Stored in walk-in refrigerator at 4 C (39 F) for up to 2 days Served directly from container onto customer’s plate with ice cream scoop Celery and red pepper from grocery store Eggs boiled for 10 min. Potatoes cooled and cubed Wooden cutting board cleaned with Washed and soapy cloth chopped Eggs sliced Cubed potatoes marinated in French dressing Same wooden spoon used to get mayonnaise and all mixing Potato salad placed in resealable container (cylindrical 8 in. x 14 in. ) Paprika sprinkled on top Brand Z Paprika from grocery store Potatoes, celery, red pepper, and eggs mixed gently with wood spoon 4 cups of mayonnaise added and stirred into mixture with wooden spoon Chopped parsley stirred into mixture Potatoes cooled and parsley washed and chopped finely Fresh parsley from grocery store 30
4. COLLECTION OF SAMPLES Collect food, water, and environmental samples based on suspicions about outbreak source Consult with laboratory on collection, storage, and transportation procedures Collect as soon as possible and note condition (may store for testing at later time) 31
5. WORKER INTERVIEWS Interview in private Reconstruct preparation of implicated food during period of interest Note unusual circumstances during period of interest and inconsistencies in the story Collect information about food worker hygiene and recent illnesses 32
6. COLLECTION OF RECORDS Collect and review Records that identify source of food or ingredients (e. g. , receipts and invoices) Worker logs or time cards Monitoring logs (e. g. , temperatures in walk-in refrigerators) 33
SMALL GROUP EXERCISE Divide into groups by table. 1. Study the information provided on an outbreak of salmonellosis linked to a restaurant. 2. Walk through the environmental health assessment of the restaurant, answering the questions. 3. Do you see contributing factors likely to be related to the outbreak? Be prepared to share with class. Time: 15 minutes 34
SMALL GROUP EXERCISE (CONT’D) An outbreak of gastrointestinal illness is linked to a local restaurant. Seven unrelated restaurant patrons are sick with abdominal pain, nausea, vomiting, and diarrhea. Onset of illness among cases was January 22 -24. Two ill patrons had stool specimens positive for Salmonella. Question 1: You are responsible for undertaking the environmental health assessment. How would you prepare for the investigation? • Examine available information on the outbreak. • Collect existing information on the facility. • Review basic information on salmonellosis. 35
SMALL GROUP EXERCISE (CONT’D) The restaurant is known for its burgers but serves a variety of sandwiches and salads. Based on patient interviews, ill persons ate at the restaurant on January 20. All but one ate chicken salad; three ill persons had only chicken salad. Question 2: What type of activities will you undertake at the facility? Focus on chicken salad: • Talk with manager • Determine who prepared the chicken salad • Walk through the facility • Observe preparation of chicken salad • Interview worker to reconstruct past events • Determine worker food preparation knowledge • Collect left over chicken salad 36
SMALL GROUP EXERCISE (CONT’D) Question 3: Given the causative agent (Salmonella), implicated food (chicken salad), and setting (food service establishment), what contributory factors will you be looking for? • • • Cross contamination Inadequate refrigeration Improper holding temperatures Heat process failure Improper cooling 37
SMALL GROUP EXERCISE (CONT’D) The manager tells you two employees (Willard and Anita) usually make the salad. Making the chicken salad is a 2 -day process. You interview the employees to reconstruct how the salad was made. 38
SMALL GROUP EXERCISE (CONT’D) 39
SMALL GROUP EXERCISE (CONT’D) Question 4: Draw a flow diagram for preparing the chicken. Wash chicken under running water and trim (70 F) Remove to packaging area Place in walk-in refrigerator single layer/ not covered Cook • Remove from refrigerator • Debone • Dice Place in tubs and transport to cooking area Insert rotisserie spindles Store in walk-in refrigerator in metal pan on the top shelf, covered, labeled, dated 40
SMALL GROUP EXERCISE (CONT’D) Question 5: These photos were taken as you observed the salad being made. Do any concern you? 1 41
SMALL GROUP EXERCISE (CONT’D) 2 42
SMALL GROUP EXERCISE (CONT’D) 3 43
SMALL GROUP EXERCISE (CONT’D) 4 44
SMALL GROUP EXERCISE (CONT’D) 5 45
SMALL GROUP EXERCISE (CONT’D) 6 46
DEVELOP EFFECTIVE INTERVENTIONS Immediate control measures § Hold § Seize § Cease/desist § License sanctions § Menu limitation § Embargo § Closure § Worker exclusion or restrictions § Recalls Long term strategies to prevent recurrence § HACCP plan § Risk control plans § Training § Menu/supplier/recipe modifications 47
TRACEBACK INVESTIGATIONS 48
TRACEBACK INVESTIGATIONS Process used to determine the production and distribution chain of an implicated food Purpose: § Identify product so that it can be removed from further consumption § Determine likely origin of food safety problem § Strengthen epidemiologic associations between food and illness Formal regulatory traceback vs. informational traceback 49
RESULTS OF TRACEBACK INVESTIGATIONS CASES POINT OF SERVICE ESTABLISHMENTS DISBUTORS/ IMPORTERS Grocery Store A Case #1 PRODUCERS/ PROCESSORS Domestic Producer A Restaurant A Distributor A Case #2 -4, 6, 8 Cafeteria X Distributor B Case #5, 7, 13 -17 Restaurant B Case #7, 9 -12 Deli A Domestic Producer B Distributor D Domestic Producer C Importer X Distributor C Foreign Producer A 50
ROLE OF LOCAL HEALTH DEPARTMENTS Undertake scientifically sound investigations to § Implicate specific food item § Rule out end user contamination Interview cases for product details and where they purchased the food (e. g. , receipts) Collect paperwork (e. g. , receipts, invoices, shipping documents) from retail food establishments 51
TRACEFORWARD INVESTIGATIONS Once source of outbreak identified: Process used to trace distribution of all implicated lots of food from the original source (not just foods eaten by known cases) Purpose § Support recall efforts § Support further case-finding § Test hypothesis about source 52
EXAMPLE - TRACEFORWARD Case #1 Domestic Producer A Grocery Store A Restaurant A Distributor A Domestic Producer B Case #2 Case #3 -6 Cafeteria X Case #8 -17 Restaurant B Distributor C Domestic Producer C Importer X Foreign Producer A 53
EXAMPLE - TRACEFORWARD Cases Case #1 Grocery Store B Grocery Store A Restaurant A Domestic Producer E Domestic Producer D Distributor C Domestic Producer C Distributor A Case #2 Case #3 -6 Cafeteria X Case #8 -17 Restaurant B Cases Grocery Store C Cases Distributor B Distributor E Processor A Domestic Producer F Deli A 54
§ § § SALMONELLA TYPHIMURIUM AND PEANUT BUTTER Cluster of S. Typhimurium detected by Pulse. Net. Studies implicate peanut butter sold to institutions and peanut butter crackers. Outbreak traced to one plant. Initial recall of specific lots of peanut butter expanded to include all peanuts and peanut products from implicated plant. FDA performs traceforward. Ultimately 3, 900 products recalled from several hundred companies. 55
QUICK QUIZ 56
QUICK QUIZ 1. Which of the following statements is true about contributing factors? A. An outbreak will occur if a contributing factor is present. B. The three major categories of contributing factors are contamination, survival (lack of inactivation), and proliferation. C. Contributing factors in an outbreak depend on the causative agent but not the food vehicle or processing method. D. Correction of the contributing factor will correct the food safety problem and prevent it from occurring again. 57
QUICK QUIZ 2. An environmental health assessment of a food establishment undertaken during an outbreak investigation is similar to a regulatory inspection except it focuses on the past. A. True B. False 58
QUICK QUIZ 3. To prepare for an environmental health assessment, the investigator might consult which of the following? A. B. C. D. Team epidemiologist Laboratory staff Regulatory inspector facility All of the above 59
QUICK QUIZ 4. All of the following activities might be performed during an environmental health assessment of the implicated facility in an outbreak EXCEPT A. Interview of the manager of the implicated facility B. Walk through of the facility C. Collection of information from ill food workers D. Observation of all food preparation processes undertaken at the facility 60
QUICK QUIZ 5. Staff from local health departments are likely to be responsible for all of the following activities during a traceback investigation EXCEPT A. Interview of cases for product details B. Determining whether contamination at the food service facility is the source of the outbreak C. Collection of paperwork from the implicated food establishment D. Detailed analysis of receipts and invoices 61
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