Our vision: Healthier communities, Excellence in healthcare Our values: Teamwork, Honesty, Respect, Ethical, Excellence, Caring, Commitment, Courage Environmental Investigations Prepared by Dr Craig Dalton Public Health Physician Viet Nam Advanced Foodborne Disease Investigation Course
2 Outline Basic food hygiene concepts The roles of epidemiologists and environmental health officers Defining the “Epidemiologically targeted” Environmental Investigation How it differs from a “routine” environmental inspection Environmental Investigation Scenarios
4 Improper cooling of foods Improper cooking of foods Improper reheating of foods Improper holding temperature of foods Cross contamination Infected food handlers, poor employee hygiene Unsafe food or water sources Major Causes of Foodborne Disease
5 FDA 2001 – can’t easily define hazardous foods ~ The FDA’s proposed new definition defines the acceptance criterion for a Potentially Hazardous Food as being less than a 1 log increase of a pathogen when the food is stored at 24 °C (75 °F) for a period of time that is 1.3 times the shelf life as determined by the manufacturer.
6 Australian Food Standards Code 2002 Potentially hazardous foods are foods that meet both the criteria below: they might contain the types of food-poisoning bacteria that need to multiply to large numbers to cause food poisoning; and the food will allow the food-poisoning bacteria to multiply.
7 The following foods are examples of potentially hazardous foods: (Usual suspects:meat, seafood, dairy but also…) processed fruits and vegetables, for example salads and cut melons; cooked rice and pasta; foods containing eggs, beans, nuts or other protein-rich foods such as quiche, fresh pasta and soy bean products; and foods that contain these foods, for example sandwiches, rolls and cooked and uncooked pizza. Australian Food Standards Code 2002
8 Hazard Analysis Critical Control Point (HACCP) System Identify hazards Identify control points Specify critical limits Monitor critical limits Corrective action for critical limits Verify system works Keep records of monitoring of system
9 Examples of Critical Control Points Pasteurisation of milk to control salmonella Canning to control botulism Radiation Cooking Salt Drying
10 Food safety control points Whole of food chain approach Farm to table Field to fork Paddock to plate
11 How NOT to think Food x is safe, food y is unsafe Food is sterile and any level of bacteria presents a hazard Inspection always identifies contamination/hazard Its “always the chicken” or the foodhandler
12 Foodborne Disease Outbreaks, Cases and Deaths, Australia 1995 – 2000 by Setting
13 Percentage of Outbreaks by Vehicle (Vehicle Level 1)(N=214) Miscellaneous Non-dairy bev Specialty/ethnic Unknown Dairy Fruit Grains Vegetables
14 Percentage of Cases by Vehicle Type (N=7810) 49% Chicken
15 Temperature and Bacteria Control 120 115 Canning temperatures for low-acid vegetables, meat, and poultry in pressure canner 100 52 49 - 20 74 60 37 16 7 0 -18 0C0C Some bacterial growth; many bacteria survive Canning temperatures for fruits, tomatoes, and pickles in waterbath canner Water freezes Growth of bacteria is stopped, but bacteria level before freezing remains constant and not reduced Keep frozen foods in this range Water boils Most bacteria destroyed No growth, but survival of some bacteria Hottest temperature hands can stand Extreme DANGER ZONE. Rapid growth of bacteria and production of poisons by some bacteria Body temperature – ideal for bacterial growth 4 Slow growth of some bacteria that cause spoilage Some growth of food poisoning bacteria may occur DANGER ZONE Source: Keeping Food Safe to Eat, USDA
16 Bacterial Growth Curve Number of Cells Time Decline Phase Stationary Phase Log Phase Lag Phase
17 Effect of Temperature in Salmonella Growth Number of Salmonella per gram Days 21 453 95 o F (35 o C) 50 o F (10 o C) 44 o F (6.7 o C) 42 o F (5.5 o C)
18 Pathogens transmitted by foodhandlers Exercise on white board 1.lets list all of the pathogens 2.Then rank them by ease of transmission
19 Roles in Environmental Investigations Environmental Health Officers Understand regulations and food manufacturing processes Understands food microbiology Traceback and supply sources Epidemiologists Aligns investigation with epidemiological hypotheses Explore and test hypotheses Gain greater understanding of food preparation methods
20 Not talking about routine inspection Routine environmental inspections conducted to ensure compliance with regulations or food safety programs. Conducted on a regular basis Facilities assessed against specific criteria on a form Covers a wide range of food safety, management and training issues Tend to focus on what can be seen e.g. Cleaning and structural issues
25 Yes! You cannot “see” all of the food safety problems during an inspection You have to “ask” about them. Interview with chef is very important
26 Epi-targeted Environmental Inspections Focused on exploring epidemiologically supported hypotheses –Descriptive epi.: incubation period, symptom profile, complaints about food –Analytical epi.: relative risk may implicate particular food. Environmental inspection may/should occur before epidemiological analysis is complete. Need to maintain balance between jumping to conclusions and using environmental inspection to explore your hypotheses.
27 The interview Interview of chef about food preparation should be so detailed that YOU could prepare the dish if you had to. Need to be able to visualise the whole process. Don’t ask leading questions that have yes or no answers, ask them: “Tell me how you make this meal and let them tell the story. Don’t assume the chef will “lie” about their food safety errors – sometimes they won’t know what errors they are making.
28 The inspection When you have finished your epi targeted inspection - stand around and watch what happens. How often do staff wash their hands? Are they separating raw and cooked foods? Spending an hour just watching the kitchen operation will reveal so much. Don’t assume they will be on “good behaviour” while you are there – they may not know good behaviour.
29 Specimen collection Collect generous amounts in sterile jars. Put in cooler with ice packs. Transport rapidly to laboratory. Label all specimens – what,where, when, who collected, outbreak code. Love these specimens like your children and know where they are every hour of every day!
30 Outbreak scenario 1 Interviewed 8 people who report onset of illness 24 to 48 hours after eating a banquet featuring roast duck and a variety of fresh salads. All 8 experience severe abdominal cramps, high temperatures and diarrhoea, with 7/8 contain blood and mucus What pathogens and what foods are we thinking what will the focus our environmental investigation be? (check your list of pathogen incubation periods and symptom profiles.)
31 Outbreak scenario 1 1.Shigella Possible sources: infected food handlers handling salad, contaminated drinking water, salad vegetables contaminated preharvest Interview: illness among food handlers, hygiene training of food handlers, sources of salad vegetables, washing of vegetables on receipt, water sources. Inspection: Hand washing practices of staff, hand washing facilities (soap?), condition and storage of salad vegetables, protection of water supplies. Specimen collection: Stool samples from food handlers, salad vegetables, drinking water, washing water (consider other bacterial enteritis agents)
32 Outbreak scenario 2 40 people ill after a banquet. Buffet: pork, fish, rice and noodles. Onset of illness 2 to 5 hours after the buffet Of 10 ill people interviewed, 8 report severe nausea and vomiting and 2 others report same plus diarrhoea. What pathogens and what foods are we thinking what will the focus our environmental investigation be? (check your list of pathogen incubation periods and symptom profiles.)
33 Outbreak scenario 2 1.Suspect Bacillus cereus Possible sources: temperature abused rice or other grain based foods. Interviews: How is rice, noodles made, stored, time and temperature, preparation times, serving times. Inspection: Are there thermometers in refrigerators or available for checking food temp., how big are the rice/noodles storage containers, how is rice stored now. Specimen collection: Rice for spore count. (consider other short incubation period toxins e.g. Staph. Aureus)