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Projects for Specific Foodborne Pathogens

Salmonella

Salmonella risk model (ESR Food, 2003-2005)

Salmonellosis is the second most frequently reported bacterial gastrointestinal illness in New Zealand, and because of the common perception as "foodborne" of origin, in particular through poultry meat, ranks high for NZFSA risk management action. By elucidating the main pathways by which consumers are exposed to Salmonella, this project will help NZFSA achieve its strategic goal of reducing the incidence of foodborne illness in New Zealand. The goal of this project is to assist risk management of Salmonella in poultry by creating a preliminary draft risk model.

Microbiological survey of uncooked retail meat products (ESR Food, 2003-2005)

This project is a multi-year, countrywide survey of the prevalence and levels of Salmonella, shiga-toxin producing E. coli (STECs) and E. coli O157:H7 in retail beef, sheep, veal, and pork meat products. While significant data for Salmonella are available from the National Microbiological Database programme for all species other than pig meat, the data are from different locations in the supply chain and products are not necessarily comparable. Similarly, STEC and E. coli O157 data is available only for beef and veal products early in the supply chain. The objectives of this project are to define the relative proportionality of exposure and of the disease burden imposed by the various meat species through microbiological survey and by PFGE sub-typing isolates for comparison with human case isolates through the National Typing Database. The project will identify the most appropriate meat species for which to implement risk management options.

Salmonella in chicken nuggets (ESR Food, 2003-2004)

This project has as its goal to assist risk management of Salmonella in poultry by assessing the risk from Salmonella in chicken nuggets. Chicken nuggets are a partially cooked retail product that may be perceived by consumers as fully cooked and therefore be handled in an unsafe manner in domestic environments. This project will augment the review of the Salmonella in poultry Risk Profile, and provide information to the risk model for Salmonella in poultry meat. It will also assist in the development of a preliminary draft risk model for Salmonella in poultry in New Zealand. Data from this project also will be compared with two further Salmonella projects performed in parallel, covering 1) microbiology of uncooked retail meat products and 2) vertical chain estimation of prevalence of Salmonella in raw poultry from end of primary/secondary processing to retail outlets, and with any future risk assessments. This project has two main objectives: to examine and describe the production of chicken nuggets in New Zealand and to qualitatively evaluate the risks of chicken nuggets in an expanded Salmonella in poultry risk profile.

Vertical chain survey (ESR Food, 2003-2004)

The goal of this project is to compare the prevalence and levels of Salmonella through the production chain to retail. Salmonellosis is the second most frequently reported bacterial gastrointestinal illness in New Zealand, and because it is commonly perceived to be foodborne in origin, through poultry meat in particular, it ranks high for NZFSA risk management action. NZFSA's strategic goal is to reduce the incidence of foodborne illness in New Zealand, but the achievement of this requires robust data. We have identified discrepancies between Salmonella prevalence data as recorded in the National Microbiological Database and some studies carried out on retail products. The steering group therefore believes that a matched, traceable, vertical study of Salmonella in poultry meat is necessary to identify the most appropriate location in the supply chain to implement risk management options.

Pathogen loading on freshly slaughtered chickens (ESR Food, 2004-2006)

The Campylobacter on poultry meat risk modelling project has identified a significant data gap concerning the number of Campylobacter on birds at the beginning of processing in New Zealand. It is likely that a similar data gap will be identified in the Salmonella on poultry meat modelling project. Most steps in processing can be modelled as changes in numbers on carcasses, but the initial distribution in numbers is required so that the model can produce a distribution of numbers after processing. The goal of this multi-year project is to provide data on the prevalence and numbers of Campylobacter and Salmonella on freshly slaughtered chickens immediately after exsanguination and prior to scalding.

Salmonella on the surface of eggs (ESR Food, 2004-2005)

Salmonellosis is one of the most frequently reported foodborne illnesses in New Zealand and ranks high for NZFSA risk management action. While Salmonella contamination in and/or on eggs has been shown to make a significant contribution to human foodborne illness in several overseas countries, the relationship between consumption of eggs and human salmonellosis in New Zealand is not clear. Although a small study undertaken in Auckland in 2002 found 14% of egg samples contained Salmonella as a surface contaminant, a link to human illness was not determined. The goal of this project is to carry out a pilot quantitative survey of Salmonella on the surface of battery eggs produced in New Zealand for retail sale in Auckland and Christchurch to enable a more accurate estimate of exposure to Salmonella from this source, and to identify the serotypes that predominate in New Zealand. In addition, the microbiological consequences of egg washing will be examined.

Microbiological survey of imported and domestic pork (ESR Food, 2004-2005)

The strategic requirement of NZFSA to reduce the level of foodborne illness in New Zealand requires a robust understanding of the proportionality of exposure of various pathogens from different food groups, in this case pig meat from domestic and foreign sources. New Zealand imports approximately a third of its pig meat requirements. Salmonellosis is the second most frequently reported bacterial gastrointestinal illness in New Zealand. Overseas pig meat is considered a significant source of Salmonella exposure for consumers as is E. coli O157:H7, an emerging disease especially in terms of market access. The goal of this project is to carry out a pilot survey of uncooked imported and domestic pig meat prior to secondary processing for the presence of Salmonella and E. coli O157:H7, and presence/numbers of generic E. coli in order to answer questions of proportionality of exposure; to assess the likelihood of introducing novel and pathogenic serotypes into New Zealand; to provide a guide for evaluation of food safety programmes (FSP) for uncooked comminuted fermented meats (UCFM); and to provide a guide for development of the pork National Microbiological Database (NMD).

Assessment of domestic food handling practices (ESR Food, 2004-2006)

A significant portion of foodborne illness is thought to be caused by unsafe food handling practices in the home. Data on the food handling practices of New Zealanders is limited, with the main sources being three postal and telephone surveys conducted in the 1990s. More accurate and better targetted information is needed to support risk management, particularly the development of risk models to assess potential interventions. A quantity of data is available from Australia, and although this may be useful in some areas are not be applicable to New Zealand. ESR will collate information on consumer food handling via direct measurements in homes and interviews with the public. Information gathered will include the temperature during transport from the retail outlet to the home, the temperature of domestic refrigerators, and room temperatures with respect to defrosting and handling. The potential for cross-contamination will be assessed through observation of the layout of food stored in refrigerators with particular emphasis on the storage of raw meat and poultry in relation to ready-to-eat foods, and microbiological analysis of food contact surfaces. Domestic handling will be simulated in the laboratory to provide quantitative information, especially in relation to transfer rates for bacteria on surfaces.

Temperature control at retail level (ESR Food, 2004-2005)

A number of quantitative risk assessments for major foodborne microbiological hazards currently under development by NZFSA require a better understanding of the handling of meat during retail processing and storage in order to better determine the extent of pathogen growth at different stages, and under different circumstances. The goal of this study is to acquire a better understanding of the adequacy of temperature control of meat (sheep and poultry) during transport between the slaughterhouse and retail outlet, and during retail processing and display.

National typing database (ESR Food, 2003-2005)

A standardised, national, pulsed-field gel electrophoresis (PFGE) microbial sub-typing database is being implemented to allow more effective detection of clonal linkages between human case isolates and food/environmental isolates of Campylobacter, Salmonella, Shiga-toxigenic E. coli (STEC) and Listeria. The National Typing Database will be an important tool facilitating the identification of factors that, if controlled, should reduce the burden of human gastroenteritis in New Zealand. In addition, subsequent research directions will be identified that will enable better management the risks of food-borne disease. All NZFSA sponsored projects that isolate the aforementioned zoonotic hazards will be required to subtype isolates and submit the data to the National Typing Database. The aim of this continuing project is to provide food-specific input into the development of the National Typing Database though completion of PulseNet certification, participation in testing the pilot system, and validation of results from historical NZFSA and MoH projects against the new procedures.