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Our vision: Healthier communities, Excellence in healthcare Our values: Teamwork, Honesty, Respect, Ethical, Excellence, Caring, Commitment, Courage Designing

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Our vision: Healthier communities, Excellence in healthcare Our values: Teamwork, Honesty, Respect, Ethical, Excellence, Caring, Commitment, Courage Designing and conducting a model investigation of foodborne disease Prepared by Dr Craig Dalton Public Health Physician For Viet Nam Food Authority 8 th June 09 Slide 2 2 Outline What does the model outbreak investigation look like How does the model outbreak support a model food safety system What are the key needs to achieve the model foodborne outbreak system Slide 3 3 Start with a story.. Outbreak investigation is important because: Helps control current outbreak Helps us learn how to prevent future outbreaks Slide 4 In 1993, as a trainee foodborne disease epidemiologist, I realised that my 9 year old niece knew more about the epidemiology of Salmonella in the USA than I knew about Salmonella in Australia! I was trying to stop her brother putting this frog in his baby sisters mouth because it might cause salmonellosis. She said: Uncle Craig,dont worry about frogs - eggs are the main cause of Salmonella! Slide 5 5 What makes a 9 year old so smart? Good outbreak investigations National database of foodborne outbreaks Good communication of problem: Foods Food preparation errors Settings Slide 6 Salmonella outbreaks, USA, 1992 80 Salmonella outbreaks 60 outbreaks due to S. Enteritidis Eggs implicated in 22/25 (88%) with known food Deaths in nursing homes Recommendation: pasteurised eggs Slide 7 What is the commonest cause of salmonellosis in Australia? Questions we couldnt answer Slide 8 What is the major food handling error responsible for foodborne disease in Australia ? ? Lack of handwashing ? Temperature abuse Slide 9 We needed a national outbreak database Outbreak report No. ill:35 Bug: S. agona Association:Relative risk of 9 Vehicle: Egg rolls Contributing factors: Temp abuse Setting: Restaurant Outbreak report No. ill: 35 Bug: S. agona Association:RR of 9 Vehicle: Egg rolls Cont factors: Temp abuse Setting: Restaurant Slide 10 10 Every outbreak is a lesson in prevention A national database of foodborne outbreak data is a database of lessons in prevention. Need good outbreak investigations to capture these lessons expert teams that mentor Standardised methods of investigation and documenting the outbreaks. Manuals that help standardise practice Standard case definitions, questionnaires Standard data entry forms for national database Can be online Slide 11 11 Slide 12 12 Training and practice in model outbreak investigation methods Standard Outbreak Reports Pathogen Place Food Hygiene practices Slide 13 13 Standardising questionnaires NetEpi web based questionnaires Used in large distributed outbreaks Slide 14 14 Using Outbreak Summary Data Summary data can inform policy work by other agencies Summarise by commodity or by aetiology Important to feed back to regulation/intervention complex web of food production and food safety Broader attribution efforts Slide 15 Benefits HACCP food safety programs based on causes of foodborne disease in your own jurisdiction Prioritise food safety policy based on true morbidity and mortality NOT media or local folklore Assess effectiveness of prevention programs Slide 16 16 The Model Foodborne Outbreak Investigation Slide 17 17 Steps of an outbreak investigation Establish the existence of an outbreak Verify the diagnosis Defining and counting cases Determining the population at risk Descriptive epidemiology Developing hypotheses Evaluating hypotheses Additional epidemiological, environmental and laboratory studies Implement control and prevention measures Communicate findings Slide 18 18 Establish existence of an outbreak Definition: a) The observed number of cases of a particular disease exceeds the expected number. b) The occurrence of two or more cases of a similar foodborne disease resulting from the ingestion of a common food. Slide 19 19 Verifying the diagnosis Diagnosis may be Syndromic e.g. vomiting and diarrhoea Laboratory Laboratory diagnosis helps ensure we are comparing apples with apples rather than parasitic diseases with bacterial diseases. Slide 20 20 Defining and counting cases Case definition Time, person, place Case definition for salmonella outbreak Suspect : All persons with diarrhoea (3 or more loose stools) and abdominal cramps within one week of attending the feast. Confirmed case: suspect case with salmonella of same serotype isolated from stool. Depending on local epidemiology of salmonellosis we may need salmonella serotyped or further subtyped to ensure were are comparing apples with apples) Slide 21 21 Gastroenteritis after an awards ceremony Approximately 3000 attendees Awards for State Emergency Services for Thredbo landslide disaster response Reports from Hunter SES of diarrhoea 19 hours post lunch Outbreak reported 3 days after luncheon Slide 22 22 Established outbreak & case finding Multiple bus loads of Emergency Volunteers returned all over the state Obtained a list of volunteer groups and contacted them asking about symptoms Kept a team of 8 people back to 11pm calling organisers, tracking down and interview cases and well people. Many reported diarrhoea, no other common link apart from the awards luncheon. Slide 23 23 Verifying diagnosis No specimens available at time of report Clinical case definition: Attended luncheon at Governors mansion Onset of diarrhoea* within 3 days of luncheon Collected specimens Drove to cases houses Left stool collection kit Paged us when stool sample ready for pick up Slide 24 24 Remove barriers to specimen collection call twice daily to check give written advice on how to collect stool specimens provide containers, refrigeration block. pick up from patients home run a clinic consider rectal swabs Slide 25 25 Descriptive epidemiology 171 persons met the case definition defined as eating at the luncheon and reporting diarrhoea that lasted more than 9 hours or diarrhoea that was accompanied by abdominal cramps or vomiting in the 3 days after attending luncheon. Median incubation period 9 hours (range, 9 to 48 hours) Median duration of illness was 24 hours (range, 1 to 96 hours). Slide 26 26 Descriptive epi - Symptoms Diarrhoea 100% Abdominal cramps 72% Nausea 30% Vomiting 15% Fever 5% So what pathogen is this symptom profile and incubation period consistent with? Slide 27 27 Environmental investigation Catered function prepared off site It was the largest function ever catered by this caterer (3,000 people) Cooked foods days ahead Ran out of cool room space Food for lunch delivered into tents from 4am in the morning and stored under tables and consumed from 1pm to 4pm (up 12 hours after delivery!) No food for testing Slide 28 28 Food specific attack rates Awards Ceremony Persons ate specified food Persons did not eat specified foods FoodIll/TotalAttack rate (%) Ill/TotalAttack rate (%) Relative Risk 95% CI Chicken116/19460%9/3426%2.31.3-4.1 Ham111/18759%17/3845%1.30.9-1.3 Beef110/17663%19/4939%1.61.1-2.3 Potato salad103/16961%22/5342%1.41.0-2.0 Pasta salad90/14164%32/7046%1.41.0-1.8 Slide 29 29 Dose response for chicken consumed by those who reported ill after attending the luncheon Chicken servings N= 49 IllNot ill Relative risk 95% CI 018Reference 117 4.50.6-29.4 2717.81.2-50.9 Slide 30 30 Laboratory results Disaster! Stool samples lost for 2 days Stool samples had low counts of clostridium perfringens spores (< 10 6 spores per gram) Laboratory comes to our rescue with Pulsed Field Gel Electrophoresis Slide 31 31 PFGE of C. perfringens outbreak .. Similar pattern suggesting common exposure Slide 32 32 Prevention Food inspector blitz on caterers Entered into our database Yet more evidence that weekend and offsite catering is associated with outbreaks due to inadequate temperature control Slide 33 33 Was this a model outbreak? Common pathogen Good and rapid case finding Aggressive collection of stool specimens Did not rely on health clinics or hospitals Epidemiological techniques including dose- response analysis helped identify the chicken Close liaison with laboratory enabled novel testing that confirmed cause Slide 34 34 Benefits of OzFoodnet Oubreak Register Slide 35 35 National Outbreak Register Outbreak register Centralized collection of outbreak reports Retrospective Data collected one quarter in arrears Accuracy and completeness Data accessible through ad hoc data requests Slide 36 36 Outbreak Register Key Fields Outbreak sequence number Year, first case onset, last case onset State Number ill, hospitalised, died Setting food prepared Mode of transmission Vehicle Remarks Slide 37 37 Outbreak Register Data Updated to September 2007 (except VIC) 4688 outbreaks 638 (14%) foodborne or suspected foodborne 3598 (77%) person to person 108,421 people ill 3058 hospitalised 120 deaths Slide 38 38 Foodborne Outbreaks, 2001- Sep 2007 638 foodborne or suspected foodborne outbreaks 10,424 people ill 815 hospitalised 13 dead Setting 40% in restaurants Aetiology 31% Salmonella species 73% Salmonella Typhimurium 39% Unknown Slide 39 39 External Data Requests Requests received from Industry partners Government partners General public Academics Many parties interested in the data Slide 40 40 Case Study: Egg Associated Outbreaks Slide 41 41 Egg-Associated Outbreaks 75 egg-associated outbreak reports from January 2001 to April 2007 1222 cases, median 9.5 (2-213) 361 hospitalised, 3 deaths Data provided to FSANZ Standards Development Committee (developing primary production standard) Slide 42 42 Egg-Associated Outbreaks, 2001 April 2007 Slide 43 43 Enhanced Data, Egg-Associated Outbreaks Collected enhanced data on 67 of 75 egg-associated outbreaks 58% (39/67) associated with uncooked eggs 84% (56/67) Salmonella Typhimurium 37% (25/67) had environmental testing of farm 76% (19/25) of these

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