04. A ‘farm-to-fork’ risk assessment on the adverse effects to human health of Salmonella typhimurium in pigs (original) (raw)
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International Conference on the Epidemiology and Control of Biological, Chemical and Physical Hazards in Pigs and Pork, 2015
Pork and products thereof are known important sources of Salmonella to humans with particular concern to S. Typhimurium and S. Derby. The purpose of this work is to present potential risk factors for Salmonella Derby or S. Typhimurium in feces in Danish breeding pig herds, using data from the EU baseline survey on prevalence of Salmonella in breeding pigs, 2008. Multi-level multivariable analysis including 2930 pens (12 variables) within 293 holdings (7 variables) was carried in SPSS version 22 using GLMM. Three outcomes were assessed, based on Salmonella positivity or negativity of the pens' fecal pools: one binomial (Salmonella positive or negative pool); two multinomial outcomes, one with S. Typhimurium positive or S. non-Typhimurium positive or Salmonella negative pools and the other with S. Derby positive or S. non-Derby positive or Salmonella negative pools. Potential risk factors (p<0.05) for Salmonella positivity were: total number of breeding pigs, boar replacement policy and type of feed; S. Typhimurium-dependent potential risk factors were boar replacement policy and type of feed; S. Derby-dependent potential risk factors were boar replacement policy, type of feed and source of feed. The results from our analysis for Salmonella spp are in line with the conclusions from the EFSA report at the EU-level. Differences are that fewer associations were found in Danish data, with the variable boar replacement policy being retained in all three final models. A similar association was found in Portugal, which was source of semen. Results from Denmark and Portugal retained potential similar associations but full comparability was not possible due to some differences in the statistical methodology. Serotype-specific risk factor investigation revealed different risk associations for S. Typhimurium in Portugal and Denmark. Serotype-specific risk associations for S. Typhimurium and S. Derby in Denmark showed some differences which will be discussed.
International Conference on the Epidemiology and Control of Biological, Chemical and Physical Hazards in Pigs and Pork
A farm-to-consumption quantitative microbiological risk assessment (QMRA) for Salmonella in pigs has been developed for the European Food Safety Authority. The primary aim of the QMRA was to assess the impact of reductions of slaughterpig prevalence and the impact of important control measures applied at the farm and during transport, lairage and slaughter on the number of human cases of salmonellosis. The QMRA estimates the risk of salmonellosis and number of human cases for three product types: pork cuts, minced meat and fermented ready-to-eat sausages. For four case study European Union Member States (MSs) the average probability of illness was estimated to be between 1 in 100,000 and 1 in 10 million servings given consumption of one of the three product types. The total numbers of cases attributable to the three product types was also estimated. The results from the intervention analysis suggest that specific slaughterhouse interventions are currently best placed to produce consistently large reductions in the number of human cases and that for high breeding prevalence MSs reducing infection on breeder farms would seem to be an important on-farm control measure.
Quantitative Microbiological Risk Assessment (QMRA) is a scientific tool that can be used to evaluate the level of exposure and subsequently the risk to human health. However, using this technique one should be aware of the limits of the QMRA model due to data quality, limited amount of time, model uncertainty and quality of assumptions. In addition, each information source may have different study designs, sampling methods, diagnostic tools, etc. Within the Belgian Salmonella QMRA-model in pigs, following exposure pathways were identified: primary production, transport, slaughterhouse & post processing, distribution & storage, consumer, dose response. From more than 60 available data sources, information was available for up to 101 potential input parameters, which were essential for building up the model-framework. For each parameter different specifications were summarised. In order to evaluate the quality of these input parameters and to measure their importance and possible imp...
EFSA Journal, 2010
This Quantitative Microbiological Risk Assessment (QMRA) represents a major step forward in terms of modelling Salmonella in pigs from farm to consumption as it takes into account the variability between and within EU Member States (MSs). Around 10-20% of human Salmonella infections in EU may be attributable to the pig reservoir as a whole. From the QMRA analysis it appears that an 80% or 90% reduction of lymph node prevalence should result in a comparable reduction in the number of human cases attributable to pig meat products. Theoretically, according to the QMRA the following scenarios appear possible (a) by ensuring that breeder pigs are Salmonella-free a reduction of 70-80% in high prevalence MSs and 10-20% in low prevalence MSs can be foreseen; (b) by feeding only Salmonella-free feedstuffs, a reduction of 10-20% in high prevalence MSs and 60-70% in low prevalence MSs can be foreseen; and (c) by preventing infection from external sources of Salmonella (i.e. rodents and birds) a reduction of 10-20% in slaughter pig lymph node prevalence can be foreseen in both high and low prevalence MSs. A hierarchy of control measures is suggested-a high prevalence in breeder pigs needs to be addressed first, followed by control of feed and then control of environmental contamination. Also according to the QMRA, for each MS, a reduction of two logs (99%) of Salmonella numbers on contaminated carcasses would result in more than 90% reduction of the number of human salmonellosis cases attributable to pig meat consumption. The control of Salmonella in pig reservoir in the EU is a reasonable objective. The EU Salmonella control strategy in pigs should be continuously evaluated to identify possible improvements.
Journal of food protection, 2010
Salmonella Typhimurium is the predominant serotype isolated from humans in Europe. Pork and pork products are recognized vehicles of Salmonella and are responsible for outbreaks of human salmonellosis. Pigs can become infected with Salmonella on the breeding or fattening farm and during transport, lairage, and slaughter. The aim of this study was to investigate selected points of Salmonella contamination from the time pigs entered the lairage to the time the carcass was processed in the boning hall and to determine the importance of different sources of Salmonella along the Irish pork production chain. A second objective was to evaluate whether the serological status or category of a herd influenced the levels of bacteriological contamination detected on individual carcasses and pork cuts during slaughter and dressing operations. All samples were tested for the presence and numbers of Salmonella. Enterobacteriaceae numbers were also determined. Serotype, phage type, and pulsed-field...
Pork and the number of human multi-resistant Salmonella Typhimurium DT104 cases
International Conference on the Epidemiology and Control of Biological, Chemical and Physical Hazards in Pigs and Pork
As part of a revision of the Danish Salmonella policy, we estimated the impact of nationally produced pork compared to imported pork on the number of human sporadic domestic cases of multi-resistant Salmonella Typhimurium DT104 (MRDT104) in Denmark. We also estimated the number of deaths related to the presumed excess mortality associated with MRDT104. Data on exposure from domestic and imported pork were built into a simple simulation model in @Risk, and Monte Carlo simulations were used. Our results showed that imported pork resulted in 20 times as many human cases as domestic (2 human cases per year), and 1 extra death in 50 years. If the prevalence of MRDT104 in domestic pork increased 5 times, the absolute number of human cases (related to Danish pork) would be 8-11. The excess mortality due to this rise in human cases will be negligible compared to the mortality caused by other Salmonellae.
Zoonoses and public health, 2010
The study set out to explore risk factors for Salmonella infection in pigs, based on seroprevalence amongst slaughtered pigs, using a large study population of holdings and a comprehensive list of farm characteristics. Farm data were collected from pig quality assurance schemes and supplemented by a postal questionnaire. These data were used with meat juice serology results from ongoing abattoir Salmonella surveillance, for a multivariable risk factor analysis, modelling the ELISA sample to positive ratio directly (ELISA ratio). The study population contained 566 farms, covering a geographically representative spread of farms within the United Kingdom, with a mean average of 224 sample results per holding over a 4-year period. The model highlighted that temporal factors (quarterly and yearly cycles) and monthly meteorological summaries for rainfall, sunshine and temperature were associated with Salmonella presence (P < 0.01). The ELISA ratio was found to be highest in autumn and ...
International Conference on the Epidemiology and Control of Biological, Chemical and Physical Hazards in Pigs and Pork, 2015
The present study summarises the insights yielded by different studies focused on the epidemiology of the infection by Salmonella through the pig production (breeders, finishers and post-farm stages). The final objective is to determine the best strategies for successful control of Salmonella in a highly prevalent country such as Spain. The study in breeders evidenced a high seroprevalence. There were differences among some of the 10 most common serotypes detected in breeders compared to previous studies in finishers, although the two most common were shared by both populations. Type of feed and type of floor were the factors associated to the presence of Salmonella. A Salmonella Typhimurium inactivated vaccine and two organic acids demonstrated to be good tools to reduce the prevalence in finishers. Finally a study of the contamination in post-farm stages evidenced the high contamination of transport, lairage and the contamination of the slaughter line, accounting for 70% of carcass cross-contamination.