IAFP 2009 Program Book and Abstract Book - AB45

Methods: Murine norovirus-1 (MNV) was labeled with SYBR gold, and lettuce pieces were dipped into fluorescent MNV, agitated for 5 min, incubated at 4°C for 1 h, and analyzed with use of a confocal microscope. MNV was incubated in biosolids, solid swine manure (SM) and liquid dairy manure (DM) at 4°C for 10, 20 and 30 days. Manure samples were diluted 100-fold in phosphate buffer, and lettuce pieces were dipped and incubated at 4°C up to 24 h. MNV was recovered from the lettuce with HBSS buffer and analyzed by use of the plaque assay. Results: With use of confocal microscopy, MNV was observed both on the surface and attaching to the cut edge of lettuce pieces. The guard cell was important in internalization, as MNV was observed inside it and in the tissue around it. The attachment percentage for pure MNV was ~0.02%; however, it increased 50-fold for MNV recovered from biosolids and 5-fold for SM, although it had no significant effect for MNV in DM (P < 0.001). After attachment, MNV was stable on lettuce and there was no significant reduction after a 24-h incubation for all samples (P < 0.05). The incubation time of MNV in manure and biosolids did not affect attachment, as no significant difference was observed between day zero and day 30 manure samples (P < 0.05). Significance: This is the first study to observe virus recovered from manure/biosolids and subsequent attachment and internalization to lettuce by use of confocal microscopy. T6-01 Food Commodities Associated with Salmonella Enteritidis Outbreaks 1998–2007 ALEJANDRO PÉREZ, Tracy Ayers, Ian Williams, and David Swerdlow, Centers for Disease Control and Prevention (CDC) and FDA, Atlanta, GA, USA Introduction: Salmonella serotype Enteritidis has been implicated as a major contributor to foodborne illness. An updated analysis evaluating the roles that various food commodities play in outbreak causation will provide useful insight for the development of control strategies. Purpose: Provide updated data on the roles of food commodities as vehicles of transmission for Salmonella serotype Enteritidis. Methods: We examined data on confirmed Salmonella serotype Enteritidis foodborne outbreaks with two or more illnesses investigated by state and local health agencies and reported to CDC during 1998-2007. Food items implicated in outbreaks were classified into one of seventeen food commodity categories (fish, crustaceans, mollusks, dairy, eggs, beef, game, pork, poultry, grains-breads, oils-sugars, fruits-nuts, fungi, leafy vegetables, root vegetables, sprouts, and vine-stalk vegetables). Results: A total of 391 single-etiology outbreaks due to Salmonella serotype Enteritidis were reported to the CDC between 1998 and 2007, resulting in 10,019 illnesses, 932 hospitalizations, and 14 deaths. Of these, 132 (34%) outbreaks implicated food items that could be classified into a single commodity, with the top three commodities being eggs (64% outbreaks, 62% illness), poultry (17% of outbreaks, 20% illness), and fruits-nuts (5% outbreaks, 6% illness), none of which showed statistically significant changes in frequency over time. The median size of outbreaks during this time period was greatest for fruits-nuts (28 persons), followed by poultry (15 persons) and eggs (12 persons), and did not show statistically significant changes over time. Significance: Salmonella serotype Enteritidis infections due to egg, poultry, and fruit-nut commodities comprised 86% of outbreaks due to a single commodity. Outbreaks of Salmonella serotype Enteritidis associated with eggs continue to occur, and eggs are the most frequently implicated commodity, indicating that control efforts are needed along the farmto-fork continuum. T6-02 Withdrawn T6-03 Exploring Historical Canadian Foodborne Outbreak Datasets for Human Illness Attribution JUDY D. GREIG, Andre Ravel, Carol Tinga, Ewen Todd, Grant Campbell, Mike Cassidy, Barbara Marshall and Frank Pollari Public Health Agency of Canada, Laboratory for Foodborne Zoonoses, Guelph, ON, Canada Introduction: Human illness attribution has been recently recognized as an important tool for developing a risk-based approach to manage the food supply. Analyzing outbreak datasets has been suggested and used in some countries for that purpose. Purpose: This study explored three Canadian comprehensive foodborne outbreak datasets covering 30 years for their usefulness in estimating food attribution for gastrointestinal illness and provides Canadian food attribution estimates with a historical perspective. Methods: Information on the microbiological causative agent and the food vehicles recorded for each outbreak was standardized between the three datasets. The agent-food vehicle combinations were described and analyzed for changes over time by using multiple correspondence analyses. Results: Overall, 6,908 foodborne outbreaks were available over three decades (1976 to 2005) but the agent and the food vehicle were precisely identified in only 2,107 of them. Differences existed between the datasets in the distribution of the cause, the vehicle, the location or the size of the outbreaks. Multiple correspondence analyses showed association between Clostridium botulinum and wild meat and between C. botulinum and seafood. It also highlighted changes in food attribution over time. It generated the most up-to-date food attribution values for salmonellosis (29% produce, 15% poultry, 15% meat other than poultry, pork and beef), campylobacteriosis (56% poultry, 22% dairy products other than fluid milk), and Escherichia coli infection (37% beef, 23% cooked multi-ingredient dishes, 11% meat other than beef, poultry, pork) in Canada. Because of the inherent limitations of this approach, only the main findings should be considered for policy-making. The use of other human illness attribution approaches will provide further clarification. Abstract Book — 45 Technical

IAFP 2009 Program Book and Abstract Book

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