One of the important outcomes of the risk assessment work was the compilation of a wealth of information on Salmonella in eggs and broiler chickens. The organization of these data in the structured risk assessment format has enabled the identification of the key gaps that exist in the data. This can provide guidance for future research work and help ensure that it is targeted towards generating and collecting the most useful and relevant data. These data and research needs are outlined below.
In order to improve the hazard characterization, additional outbreak and epidemiological data are needed. More specifically, these data should indicate cell number in the implicated food, amount of food consumed, accurate estimates of the size of ill and exposed populations, and accurate characterization of the population, including age profiles, medical status, sex and other potential susceptibility factors.
The impact of the food matrix was not incorporated into the hazard characterization due to the limitations of available data. So that these issues can be more completely addressed in future work, there is a need for characterization and quantification of the impact of the food matrix effects and also host-pathogen interactions and virulence factors and their effect on the probability of infection or illness, or both. Quantitative information to facilitate estimating the probability of developing sequelae following illness is also required.
As this is a developing science, the optimal models have not yet been developed. Therefore, new dose-response models that improve the ability to estimate the probability of illness would be useful.
Data relating to the biology of S. Enteritidis in eggs is needed. This need is seemingly universal in its application to previous and future exposure assessments.
Additional studies on the numbers, and factors that influence the survival and growth of S. Enteritidis in naturally (yolk) contaminated intact shell eggs are needed, as information is currently available for only 63 intact shell eggs. Enumeration data of S. Enteritidis in raw liquid egg are also required. Additional data concerning the numbers of S. Enteritidis in raw liquid egg before pasteurization would assist in reliably predicting the effectiveness of such a regulatory standard concerning egg products.
More data on the prevalence of S. Enteritidis in breeder and pullet flocks and the environment, as well as in feedstuffs, is needed to adequately assess the benefit of pre-harvest interventions. In particular, associations between the occurrence of S. Enteritidis in these pre-harvest steps and its occurrence in commercial layers should be quantified.
Better data on time and temperature, specifically in relation to egg storage, and to preparation and cooking, would serve to build confidence in the modelling results. The importance of time and temperature distributions in predicting growth of S. Enteritidis in eggs, combined with the lack of reliable data to describe these distributions, highlights the need for these data. Furthermore, new studies are needed on the relationship between cooking time, cooking method and cooking temperature and the death of S. Enteritidis.
More studies are needed on the survival and growth of S. Enteritidis in eggs, particularly as a function of egg composition and the attributes of infecting strains of organism (e.g. heat sensitivity).
As indicated earlier in the document, the lack of good quality data, prior to the end of processing in particular, limited the scope of this exposure assessment. In relation to primary production, the information available was mainly prevalence data, but for some regions of the world - including Africa, Asia and South America - even that was limited. In addition, information on study design, specificity or sensitivity of the analytical methodologies used was lacking. Very few quantitative data were available. A similar situation was observed for the processing stage. In addition, data tended to be old, and knowledge of processing practices was not readily available. In order to address these deficiencies, the areas where data collection and research efforts need to focus are identified below.
Data on prevalence for many regions of the world regarding Salmonella in broilers during production and at slaughter, and on carcasses post-processing, together with information on study design.
Microbial ecology studies to determine sources and numbers of the pathogen.
Studies on the correlation between within-flock prevalence levels and the number of Salmonella cells shed in faeces or on birds.
Precise estimates of the numbers of organisms per bird for all stages of the exposure pathway and improvements in the sensitivity and availability of cost-effective methods to enumerate small populations of Salmonella.
Between-bird (bird-to-bird) cross-contamination data suitable for modelling this phenomenon at the pre-harvest, transport and processing stages.
Data on the survival of Salmonella under chilling and freezing conditions. This information will improve the predictive microbiology component of exposure assessments relevant to international trade in poultry products.
Specific consumption data and information about food preparation practices for most geographical locations, preferably presented as portion size and frequency of consumption rather than average consumption per day.
Information on the distribution of time and temperature for storage and cooking in domestic kitchens in a variety of national environments.
Data on the magnitude of cross-contamination in the domestic kitchen and the pathways for cross-contamination.
If an attempt were made to extend the risk assessment to assess more fully pre-slaughter interventions, then more data would be required on the prevalence of Salmonella in feed and replacement stock, and on fasting prior to slaughter. Data on the effect of scalding, de-feathering, evisceration, washing and chilling processes, as well as other decontamination treatments, are needed to effectively model the benefits of control interventions at the levels of processing.
