Publications by authors named "Pirkko Tuominen"

15 Publications

  • Page 1 of 1

Antimicrobial use, biosecurity, herd characteristics, and antimicrobial resistance in indicator Escherichia coli in ten Finnish pig farms.

Prev Vet Med 2021 Aug 10;193:105408. Epub 2021 Jun 10.

Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Finland.

We investigated connections between antimicrobial use (AMU), biosecurity, and the numbers of pigs and staff in ten Finnish farrow-to-finish herds. Data on AMU in each herd were collected for 12 months. AMU was quantified as treatment incidences per 1000 days at risk (TI) using the consensus defined daily dose calculation. Biosecurity was scored using the Biocheck.UGent™ system. We also examined antimicrobial resistance patterns of indicator E. coli isolated from faeces of selected pigs. In each herd, two groups of five pigs were formed: 1) antimicrobial treatment group (ANT: at least one pig in the litter was identified as sick and treated with antimicrobials) and 2) non-antimicrobial treatment group (NON: the litter was not medicated). Faecal samples were taken from these pigs at 5 and 22 weeks of age, cultured, and indicator E. coli isolates were tested for antimicrobial susceptibilities. The AMU varied considerably between the herds. Altogether, most of the antimicrobial treatment courses were assigned to weaned piglets. When AMU was quantified as TIs, suckling piglets had the highest TI (mean 46.6), which was significantly higher (P < 0.05) than TIs in fatteners and breeders (9.3 and 7.3, respectively). The difference between TI in suckling and TI in weaned piglets (19.1) was not statistically significant. There was a tendency for a negative correlation between the TI in breeders and the number of sows (r = -0.56, P = 0.09). Larger herds had higher external biosecurity scores than smaller herds (LS-means; 72 vs. 66, P < 0.05). The proportions of E. coli isolates resistant to at least one antimicrobial were higher in pigs at 5 weeks than in pigs at 22 weeks of age (Binomial proportion means; 40.5 % vs. 15.5 %, P < 0.05); as well as proportions of isolates resistant to at least three antimicrobial classes (23.0 % vs. 3.7 %, P < 0.01). These proportions did not differ between the ANT and NON groups at either 5 or 22 weeks of age (P> 0.05). We found few connections: enhanced external biosecurity levels found in the large herds co-occurred with lower use of antimicrobials and herds with low biosecurity scores - especially in the internal subcategories - appeared to have higher proportions of resistant isolates. Conclusively, we suggest that enhancing internal biosecurity might contribute to a reduction in the spreading of antimicrobial resistance in pig herds.
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http://dx.doi.org/10.1016/j.prevetmed.2021.105408DOI Listing
August 2021

Host-Dependent Clustering of Strains From Small Mammals in Finland.

Front Microbiol 2020 13;11:621490. Epub 2021 Jan 13.

Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.

Small mammals are known to carry spp.; however, little is known about the genotypes and their role in human infections. We studied intestinal content from small wild mammals collected in their natural habitats in Finland in 2010-2017, and in close proximity to 40 pig or cattle farms in 2017. The animals were trapped using traditional Finnish metal snap traps. spp. were isolated from the intestinal content using direct plating on mCCDA. A total of 19% of the captured wild animals ( = 577) and 41% of the pooled farm samples ( = 227) were positive for , which was the only species identified. The highest prevalence occurred in yellow-necked mice () and bank voles () which carried spp. in 66.3 and 63.9% of the farm samples and 41.5 and 24.4% of individual animals trapped from natural habitats, respectively. Interestingly, all house mouse () and shrew ( spp.) samples were negative for spp. isolates ( = 145) were further characterized by whole-genome sequencing. Core genome multilocus sequence typing (cgMLST) clustering showed that mouse and vole strains were separated from the rest of the population (636 and 671 allelic differences, 94 and 99% of core loci, respectively). Very little or no alleles were shared with genomes described earlier from livestock or human isolates. FastANI results further indicated that strains from voles are likely to represent a new previously undescribed species or subspecies of . Core-genome phylogeny showed that there was no difference between isolates originating from the farm and wild captured animals. Instead, the phylogeny followed the host species-association. There was some evidence (one strain each) of livestock-associated occurring in a farm-caught and a brown rat (), indicating that although small mammals may not be the original reservoir of colonizing livestock, they may sporadically carry strains occurring mainly in livestock and be associated with disease in humans.
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http://dx.doi.org/10.3389/fmicb.2020.621490DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7873845PMC
January 2021

Salmonella Control Programme of Pig Feeds Is Financially Beneficial in Finland.

Front Vet Sci 2019 9;6:200. Epub 2019 Jul 9.

Risk Assessment Unit, Finnish Food Authority, Helsinki, Finland.

To promote public health, Finland has adopted a stringent control policy. However, the rationale of control in pig feeds has been debated after a European Union (EU)-wide cost-benefit analysis, which provided mixed, country-specific results on whether control measures are economically beneficial. The aim of this study was to analyze the costs and benefits of current pig feed control in Finland compared to a reduced control scenario. In addition, this study contributes to the literature by looking at the costs across stakeholder groups. The costs of preventive and monitoring measures were assessed, and a Monte Carlo model was developed to simulate costs caused by contaminations along the pork supply chain (including feed importation, commercial feed manufacturing, feed transportation, mobile feed mixers, pig farms, slaughterhouses) and because of human salmonellosis originating from contaminated feed. The data were collected from official records and feed sector operators by surveys and interviews. The prevalence of was obtained from a previously conducted risk assessment study. The total costs of pig feed control were estimated on average to be €4.2-5.4 million per year (95% of simulated years between €2.1 and €9.1 million) for the current control scenario, and €33.8-34.8 million per year (95% €2.2 to €26.0 million) for the reduced control scenario. In the reduced control scenario, the monitoring and prevention costs were decreased down to €1.1-2.1 million, and the costs of contaminations and human salmonellosis were up by €32.7 million when compared to the current control scenario. The results suggest that the current pig feed control policy of Finland is economically profitable. It can reduce the costs caused by feed-related contaminations on average by €29.4 million per year and provides public health benefits. Pig feed control can support the effectiveness of the Finnish Control Programme. The current pig feed control policy benefits the consumers, while a substantial part of the costs are covered by feed operators. In order to increase the acceptability of current policy, greater attention to the allocation of financial responsibilities regarding the control measures may be required.
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http://dx.doi.org/10.3389/fvets.2019.00200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629760PMC
July 2019

Listeria monocytogenes risk assessment on cold smoked and salt-cured fishery products in Finland - A repeated exposure model.

Int J Food Microbiol 2019 Sep 2;304:97-105. Epub 2019 May 2.

Finnish Food Authority, Mustialankatu 3, 00790 Helsinki, Finland. Electronic address:

Listeria monocytogenes causes severe consequences especially for persons belonging to risk groups. Finland is among the countries with highest number of listeriosis cases in the European Union. Although most reported cases appear to be sporadic and the maximum bacterial concentration of 100 cfu/g is not usually exceeded at retail, cold smoked and salt-cured fish products have been noted as those products with great risk especially for the elderly. In order to investigate the listeriosis risk more carefully, an exposure assessment was developed, and laboratory results for cold smoked and salt-cured salmon products were exploited. L. monocytogenes exposure was modeled for consumers in two age groups, the elderly population as a risk group and the working-age population as a reference. Incidence was assessed by estimating bacterial growth in the food products at three temperatures. Bayesian estimation of the risk was based on bacterial occurrence and product consumption data and epidemiological population data. The model builds on a two-state Markov chain describing repeated consumption on consecutive days. The cumulative exposure is probabilistically governed by the daily decreasing likelihood of continued consumption and the increasing bacterial concentrations due to growth. The population risk was then predicted with a Poisson distribution accounting for the daily probabilities of purchasing a contaminated product and the cumulative total probability of infection from its use. According to the model presented in this article, elderly Finns are at a greater risk of acquiring listeriosis than healthy adults. The risk for the elderly does not fully diminish even if the products have been stored at the recommended temperature (between 0 and 3 °C). It can be concluded that the stage after retail, i.e. food handling and storage by consumer or professional kitchens, is essential to protection against listeriosis. The estimation model provides means for assessing the joint impacts of these effects.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2019.04.007DOI Listing
September 2019

A Modular Bayesian Salmonella Source Attribution Model for Sparse Data.

Risk Anal 2019 08 20;39(8):1796-1811. Epub 2019 Mar 20.

Risk Assessment Unit, Finnish Food Authority, Helsinki, Finland.

Several statistical models for salmonella source attribution have been presented in the literature. However, these models have often been found to be sensitive to the model parameterization, as well as the specifics of the data set used. The Bayesian salmonella source attribution model presented here was developed to be generally applicable with small and sparse annual data sets obtained over several years. The full Bayesian model was modularized into three parts (an exposure model, a subtype distribution model, and an epidemiological model) in order to separately estimate unknown parameters in each module. The proposed model takes advantage of the consumption and overall salmonella prevalence of the studied sources, as well as bacteria typing results from adjacent years. The latter were used for a smoothed estimation of the annual relative proportions of different salmonella subtypes in each of the sources. The source-specific effects and the salmonella subtype-specific effects were included in the epidemiological model to describe the differences between sources and between subtypes in their ability to infect humans. The estimation of these parameters was based on data from multiple years. Finally, the model combines the total evidence from different modules to proportion human salmonellosis cases according to their sources. The model was applied to allocate reported human salmonellosis cases from the years 2008 to 2015 to eight food sources.
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http://dx.doi.org/10.1111/risa.13310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6849795PMC
August 2019

Dietary heavy metal exposure of Finnish children of 3 to 6 years.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2018 Jul 18;35(7):1305-1315. Epub 2018 Jun 18.

a Risk Assessment Research Unit , Finnish Food Safety Authority Evira , Helsinki , Finland.

The dietary exposure of Finnish 3-year-old and 6-year-old children to cadmium, lead, arsenic and mercury was determined using concentration data from Finland and individual food consumption data as well as individual weights of the children. Using middle bound estimates, 88% of the 3-year-olds and 64% of the 6-year-olds exceeded the tolerable weekly intake of cadmium. The benchmark dose for neurological damage caused by lead was exceeded by 14% and 1%, while the lowest benchmark dose of inorganic arsenic was exceeded by 43% and 29% for the 3-year-olds and 6-year-olds, respectively. The exposure of both age groups was below the tolerable weekly intake for inorganic mercury and methyl mercury. Although high, the exposures calculated with predominantly national concentration data were lower than previously estimated by EFSA, due to, for example, lower average concentrations in some much-consumed foods. The heavy metal exposure levels of the girls and the boys were also compared. Exposure to cadmium and lead was significantly higher for the boys than for the girls in both age groups, and exposure to inorganic arsenic was significantly higher for the 6-year-old boys than the girls of same age.
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http://dx.doi.org/10.1080/19440049.2018.1480065DOI Listing
July 2018

Bayesian model for tracing Salmonella contamination in the pig feed chain.

Food Microbiol 2018 May 31;71:82-92. Epub 2017 May 31.

Finnish Food Safety Authority Evira, Risk Assessment Research Unit, Helsinki, Finland.

Salmonella infections in pigs are in most cases asymptomatic, posing a risk of salmonellosis for pork consumers. Salmonella can transmit to pigs from various sources, including contaminated feed. We present an approach for quantifying the risk to pigs from contaminations in the feed chain, based on a Bayesian model. The model relies on Salmonella surveillance data and other information from surveys, reports, registries, statistics, legislation and literature regarding feed production and pig farming. Uncertainties were probabilistically quantified by synthesizing evidence from the available information over a categorically structured flow chain of ingredients mixed for feeds served to pigs. Model based probability for infection from feeds together with Salmonella subtyping data, were used to estimate the proportion of Salmonella infections in pigs attributable to feed. The results can be further used in assessments considering the human health risk linked to animal feed via livestock. The presented methods can be used to predict the effect of changes in the feed chain, and they are generally applicable to other animals and pathogens.
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http://dx.doi.org/10.1016/j.fm.2017.04.017DOI Listing
May 2018

Campylobacter QMRA: A Bayesian Estimation of Prevalence and Concentration in Retail Foods Under Clustering and Heavy Censoring.

Risk Anal 2016 11 9;36(11):2065-2080. Epub 2016 Feb 9.

Finnish Food Safety Authority Evira, Risk Assessment Research Unit, Helsinki, Finland.

A Bayesian statistical temporal-prevalence-concentration model (TPCM) was built to assess the prevalence and concentration of pathogenic campylobacter species in batches of fresh chicken and turkey meat at retail. The data set was collected from Finnish grocery stores in all the seasons of the year. Observations at low concentration levels are often censored due to the limit of determination of the microbiological methods. This model utilized the potential of Bayesian methods to borrow strength from related samples in order to perform under heavy censoring. In this extreme case the majority of the observed batch-specific concentrations was below the limit of determination. The hierarchical structure was included in the model in order to take into account the within-batch and between-batch variability, which may have a significant impact on the sample outcome depending on the sampling plan. Temporal changes in the prevalence of campylobacter were modeled using a Markovian time series. The proposed model is adaptable for other pathogens if the same type of data set is available. The computation of the model was performed using OpenBUGS software.
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http://dx.doi.org/10.1111/risa.12572DOI Listing
November 2016

Quantitative risk assessment on the dietary exposure of Finnish children and adults to nitrite.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2016 3;33(1):41-53. Epub 2015 Dec 3.

a Risk Assessment Research Unit, Research and Laboratory Department , Finnish Food Safety Authority Evira , Helsinki , Finland.

Nitrite intake from the consumption of cured meat and tap water was estimated for Finnish children of 1, 3 and 6 years as well as Finnish adults of 25-74 years. Nitrite content in the foods was measured by capillary electrophoresis, and was then used together with individual food consumption data from the FINDIET 2007 and DIPP studies in a stochastic exposure assessment by a Monte Carlo Risk Assessment (MCRA) program. Nitrite intake from additive sources and tap water was assessed, and more than every 10th child between the ages 3 and 6 years was estimated to have a nitrite intake exceeding the acceptable daily intake (ADI) of nitrite. The high exposure levels were caused by frequent consumption of large portions of sausages, up to 350 g day(-1) or 750 g in 3 days, among the children. Median nitrite intake from cured meat was 0.016, 0.040, 0.033 and 0.005 mg kg(-1) body weight day(-1) for children of 1, 3 and 6 years and adults, respectively. Bayesian estimation was employed to determine safe consumption levels of sausages and cold cuts for children, and these results gave rise to new national food consumption advice.
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http://dx.doi.org/10.1080/19440049.2015.1117145DOI Listing
October 2016

Intake of selected bioactive compounds from plant food supplements containing fennel (Foeniculum vulgare) among Finnish consumers.

Food Chem 2016 Mar 20;194:619-25. Epub 2015 Aug 20.

Finnish Food Safety Authority Evira, Risk Assessment Research Unit, Mustialankatu 3, FI-00790 Helsinki, Finland.

The purpose of this study was to estimate the intake of selected bioactive compounds from fennel-containing plant food supplements (PFS) among Finnish consumers. The estimated average intake of estragole was 0.20mg/d, of trans-anethole 1.15mg/d, of rosmarinic acid 0.09mg/d, of p-coumaric acid 0.0068mg/d, of kaempferol 0.0034mg/d, of luteolin 0.0525μg/d, of quercetin 0.0246mg/d, of matairesinol 0.0066μg/d and of lignans 0.0412μg/d. The intakes of kaempferol, quercetin, luteolin, matairesinol and lignans from PFS were low in comparison with their dietary supply. The intake of estragole was usually moderate, but a heavy consumption of PFS may lead to a high intake of estragole. The intake of trans-anethole did not exceed the acceptable daily intake, but PFS should be taken into account when assessing the total exposure. To our knowledge, this study provided the first intake estimates of trans-anethole, p-coumaric acid and rosmarinic acid in human populations.
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http://dx.doi.org/10.1016/j.foodchem.2015.08.057DOI Listing
March 2016

Evaluating Escherichia coli O157 control in finnish primary production.

J Food Prot 2014 Mar;77(3):371-9

Risk Assessment Research Unit, Finnish Food Safety Authority, Evira, Mustialankatu 3, FI-00790, Helsinki, Finland.

Enterohemorrhagic Escherichia coli (EHEC) has become a threat in the modern cattle sector because of its adverse impact on human health. Systems have been developed to reduce the risk of EHEC infection associated with the beef production chain. In Finland, the risk management of EHEC is mainly targeted at primary production, which is controlled by a national program. The prevalence of E. coli O157 in slaughter animals and herds appears to have remained relatively low over the years (0.2 to 1.2% and 0.3 to 1.5%, respectively). The effectiveness of the Finnish EHEC control program (FECP) was analyzed with a Bayesian statistical model based on the results from 2006 through 2010. According to the model, the estimated true prevalence of EHEC in slaughter animals was at its highest in 2007 (95% credible interval [CI], 0.94 to 1.85% of animals), and the estimated true prevalence in herds was its highest in 2007 (95% CI, 1.28 to 2.55% of herds). However, the estimated probability of the FECP detecting an EHEC-positive slaughter animal or herd was 0.52 to 0.58% and 4.74 to 6.49%, respectively. The inability to detect EHEC-positive animals was partly due to animal-based random sampling, which ignores herd-level testing and therefore emphasizes the testing of slaughter animals from herds that send more animals to slaughter. Some slaughterhouses collected samples incorrectly as a consequence of an incorrectly implemented FECP. Farmers may also have questionable reasons for choosing to send animals to be slaughtered in small abattoirs, in which testing is less likely, to avoid suspicion of EHEC or other zoonotic infections.
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http://dx.doi.org/10.4315/0362-028X.JFP-13-231DOI Listing
March 2014

Swabs as a tool for monitoring the presence of norovirus on environmental surfaces in the food industry.

J Food Prot 2013 Aug;76(8):1421-8

Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, P.O. Box 66, University of Helsinki, 00014 Helsinki, Finland.

Human norovirus (HuNoV), which causes gastroenteritis, can be transmitted to food and food contact surfaces via viruscontaminated hands. To investigate this transmission in food processing environments, we developed a swabbing protocol for environmental samples, evaluated the stability of HuNoV in the swabs, and applied the method in the food industry. Swabs made of polyester, flocked nylon, cotton wool, and microfiber were moistened in either phosphate-buffered saline (PBS) or glycine buffer (pH 9.5) and used to swab four surfaces (latex, plastic, stainless steel, and cucumber) inoculated with HuNoV. HuNoV was eluted with either PBS or glycine buffer and detected with quantitative reverse transcription PCR. HuNoV recoveries were generally higher with an inoculation dose of 100 PCR units than 1,000 PCR units. The highest recoveries were obtained when surfaces were swabbed with microfiber cloth moistened in and eluted with glycine buffer after a HuNoV inoculation dose of 100 PCR units: 66% ± 18% on latex, 89% ±2% on plastic, and 79% ±10% on stainless steel. The highest recovery for cucumber, 45% ±5%, was obtained when swabbing the surface with microfiber cloth and PBS. The stability of HuNoV was tested in microfiber cloths moistened in PBS or glycine buffer. HuNoV RNA was detected from swabs after 3 days at 4 and 22°C, although the RNA levels decreased more rapidly in swabs moistened with glycine buffer than in those moistened with PBS at 22°C. In the field study, 172 microfiber and 45 cotton wool swab samples were taken from environmental surfaces at three food processing companies. Five (5.6%) of 90 swabs collected in 2010 and 7 (8.5%) of 82 swabs collected in 2012 were positive for HuNoV genogroup II; all positive samples were collected with microfiber swabs. Three positive results were obtained from the production line and nine were obtained from the food workers' break room and restroom areas. Swabbing is a powerful tool for HuNoV RNA detection from environmental surfaces and enables investigation of virus transmission during food processing.
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http://dx.doi.org/10.4315/0362-028X.JFP-12-371DOI Listing
August 2013

Use of results of microbiological analyses for risk-based control of Listeria monocytogenes in marinated broiler legs.

Int J Food Microbiol 2008 Feb 17;121(3):275-84. Epub 2007 Nov 17.

Technical Research Centre VTT, P.O. Box 1000, FIN-02044, VTT, Espoo, Finland.

Microbial risk assessment provides a means of estimating consumer risks associated with food products. The methods can also be applied at the plant level. In this study results of microbiological analyses were used to develop a robust single plant level risk assessment. Furthermore, the prevalence and numbers of Listeria monocytogenes in marinated broiler legs in Finland were estimated. These estimates were based on information on the prevalence, numbers and genotypes of L. monocytogenes in 186 marinated broiler legs from 41 retail stores. The products were from three main Finnish producers, which produce 90% of all marinated broiler legs sold in Finland. The prevalence and numbers of L. monocytogenes were estimated by Monte Carlo simulation using WinBUGS, but the model is applicable to any software featuring standard probability distributions. The estimated mean annual number of L. monocytogenes-positive broiler legs sold in Finland was 7.2x10(6) with a 95% credible interval (CI) 6.7x10(6)-7.7x10(6). That would be 34%+/-1% of the marinated broiler legs sold in Finland. The mean number of L. monocytogenes in marinated broiler legs estimated at the sell-by-date was 2 CFU/g, with a 95% CI of 0-14 CFU/g. Producer-specific L. monocytogenes strains were recovered from the products throughout the year, which emphasizes the importance of characterizing the isolates and identifying strains that may cause problems as part of risk assessment studies. As the levels of L. monocytogenes were low, the risk of acquiring listeriosis from these products proved to be insignificant. Consequently there was no need for a thorough national level risk assessment. However, an approach using worst-case and average point estimates was applied to produce an example of single producer level risk assessment based on limited data. This assessment also indicated that the risk from these products was low. The risk-based approach presented in this work can provide estimation of public health risk on which control measures at the plant level can be based.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2007.11.037DOI Listing
February 2008

Studying the effects of POs and MCs on the Salmonella ALOP with a quantitative risk assessment model for beef production.

Int J Food Microbiol 2007 Aug 13;118(1):35-51. Epub 2007 Jun 13.

Food Safety Authority (EVIRA), Risk Assessment Unit, Mustialankatu 3, 00790 Helsinki, Finland.

The Finnish Salmonella Control Programme and the special guarantees (SG) of import concerning Salmonella in the beef production chain were examined within the risk analysis framework. The appropriate level of protection (ALOP de facto since not referred to as ALOP in regulation), performance objectives (PO), and microbiological criteria (MC) were identified along the beef production chain. A quantitative microbiological risk assessment (QMRA) model using the Bayesian probabilistic method was developed for the beef chain to evaluate the capability of different POs to contribute to the ALOP. The influence of SGs was studied as an intervention protecting Finnish consumers. The QMRA made it possible to translate an ALOP without a stated food safety objective (FSO) to POs when implemented for both ready-to-eat (RTE) and non-RTE products. According to the results, the Finnish ALOP de facto for beef, beef preparations and products (10 human Salmonella cases/100,000) was reached in all of the years 1996-2004. However, if the prevalence at the slaughter, domestic cut beef, and retail levels would increase to the level of POs set (maximum 1%), the ALOP de facto would be exceeded by a factor of roughly two. On the other hand, the zero tolerance applied to MCs would keep the true Salmonella prevalence at production steps with POs clearly below 1%, and the ALOP would then be achievable. The influence of SGs on the total exposure was so small (average 0.1% added to the total prevalence of beef-derived foods at retail) that their relevance may be doubted with the current amount and Salmonella prevalence in beef-derived imports. On the other hand, a change in import profile could increase the protective effect of the SGs. Although practical follow-up has to be carried out as apparent prevalences, the objectives and criteria should be estimated as true prevalences and incidences with quantified uncertainties in order to achieve a sound, transparent scientific-based understanding of the risk. The QMRA model developed here provided a useful tool for studying the connection between the ALOP and other targets in the production chain.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2007.05.013DOI Listing
August 2007

Estimation of true Salmonella prevalence jointly in cattle herd and animal populations using Bayesian hierarchical modeling.

Risk Anal 2005 Feb;25(1):23-37

National Veterinary and Food Research Institute EELA, Department of Risk Assessment, PO Box 45, Hämeentie 57, FIN-00581 Helsinki, Finland.

The Finnish salmonella control program (FSCP) for beef production is based on both randomized and selective testing of herds and animals. Sampling of individual animals in abattoirs is randomized. Herds are selectively tested for salmonella on the basis of clinical symptoms and/or other factors. Risk assessment of FSCP is inherently difficult due to the complexity of the complete data set, especially if the detailed labeling of the testing types is lost. However, for a risk assessment of the whole production chain, methods for exploiting all available data should be considered. For this purpose, a hierarchical Bayesian model of true salmonella prevalence was constructed to combine information at different levels of aggregation: herds in geographical regions and individual animals arriving for slaughter. The conditional (municipality specific) probability of selection of a herd for testing was modeled given the underlying true infection status of the herd and information about the general sampling activity in the specific region. The model also accounted for the overall sensitivity of the sampling methods, both at the herd and at the animal level. In 1999, the 95% posterior probability intervals of true salmonella prevalence in the herd population, in individual cattle, and in slaughter animal populations were [0.54%, 1.4%] (mode 0.8%), [0.15%, 0.39%] (mode 0.2%), and [0.12%, 0.36%] (mode 0.2%), respectively. The results will be further exploited in other risk assessments focusing on the subsequent parts of the beef production chain, and in evaluation of the FSCP.
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http://dx.doi.org/10.1111/j.0272-4332.2005.00564.xDOI Listing
February 2005
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