Parasite to Patient. Introduction. Introduction. Introduction. Data to validate a QMRA model. a QMRA for trichinellosis

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Debra Price
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Introduction Parasite to Patient EU Regulation 2015/1375 risk based surveillance in stead of individual carcass Trichinella control for all pigs a QRA for trichinellosis Frits Franssen NRL for

Recently, an expert group of FAO/WHO developed a spreadsheet model (FAO-WHO, 2014) that estimates residual risk from tested pork (controlled housing) output model in its present form: infective

for human infection Resulting in estimates trichinellosis incidence and quantification of risk from different holding systems (attributions) 2 Introduction Introduction Parasite to Patient: a

1 Introduction Parasite to Patient EU Regulation 2015/1375 risk based surveillance in stead of individual carcass Trichinella control for all pigs a QRA for trichinellosis Frits Franssen NRL for Parasites, National Institute for Public Health and the Environment (RIV), Bilthoven, the Netherlands. Recently, an expert group of FAO/WHO developed a spreadsheet model (FAO-WHO, 2014) that estimates residual risk from tested pork (controlled housing) output model in its present form: infective portions of pork Aim of the current study: to build a more detailed model, which includes modules for Trichinella distributions in meat Trichinella temperature inactivation by cooking dose-response for human infection Resulting in estimates trichinellosis incidence and quantification of risk from different holding systems (attributions) 2 Introduction Introduction Parasite to Patient: a quantitative microbial risk assessment (QRA) model for Trichinella spp any literature and experimental data Trichinella prevalence 0.4% at L in hunted wild boar n = 686,595 (EFSA , Poland) Trichinella prevalence % in domestic pigs from non-controlled housing n = 114,395,817 (EFSA , Poland) Data to validate a QRA model Conceptual model Trichinella incidence in humans observed: 264 confirmed cases out of 230 million tested ( )(EFSA , Poland) 3 1

2 #Trichinella larvae Trichinella larvae detection Trichinella at meat inspection Keep record of positive and (false) negative test results 280 PT records L p 1-p P(+Wild boar) EFSA + field data PIWet # larvae per batch 100 g diaphragm Probability to find at least one larva Positive batch False negative batch Random draw Swine ID and #larvae per animal in 100g diaphragm Probability that a portion of pork (100 g) contains two or more larvae Negative multinomial distribution Cooking model (data from Carlin et al., 1969; Randazzo et al., 2011) 100g portions Trichinella count in 100 g diaphragm temperature 10% 90% experimental infection data Bfr model probability of Trichinella allocation to swine parts time Consumption patterns 8 2

Negative 1140 pools Observed prevalence 0.4% at 0.3 211 Trichinella L / WB 114,000 wild boar ~456 positive Wild Boar 1140 pools Observed prevalence 0.4% at 0.3 211 Trichinella L / WB 114,000 wild boar 2.

3 10,000 runs 10,000 runs odules QRA model Dose-response odel Keep track of zeros! Dose-response modeling taking into account Number of larvae Proportion male and female larvae Survival of larvae after ingestion 10 QRA Simulation Simulation wild boar Negative 1140 pools Observed prevalence 0.4% at Trichinella L / WB 114,000 wild boar ~456 positive Wild Boar 1140 pools Observed prevalence 0.4% at Trichinella L / WB 114,000 wild boar pools pools missed WB in those pools (in total) WB 229 portions of shoulder, loin and belly/wb 68 92% positive portions % residual positive portions 1.97 ( ) cases//y 3

4 Total incidence Simulated incidence: 1.97 cases per million per year from wild boar 1.56 cases //year from pigs under non-controlled housing 3.53 cases //year Observed average incidence in Poland: 1.15 cases //year What about pigs from controlled housing? Two way analysis: 1. Extrapolation of incidence from non-controlled housing to controlled housing 2. Estimation of probability of finding a positive pig in a next year, given absence of Trichinella during past number of years Ad 1. Ad 2. Observed freedom of Trichinella of approximately 120 pigs from controlled housing in the whole EU per year during the last 20 years Dutch situation: 140 pigs tested in 10 preceding years, what would be the probability of finding positives the next year? That is 0 positives per 2,400 (=2.4 billion) tested, hypothesized upper prevalence limit 1/2.4 billion pigs from non-controlled housing Incidence extrapolation from non-controlled housing to controlled housing: At max 1 EU citizen with trichinellosis every 40 years! EU 2015/1375: test 10% of pigs from controlled housing!

Discussion Conclusions QRA results seem congruent with best available objective data Variability included in all stages of QRA and uncertainty in the doseresponse module Two cooking scenarios

5 Discussion Conclusions QRA results seem congruent with best available objective data Variability included in all stages of QRA and uncertainty in the doseresponse module Two cooking scenarios included, more scenarios modelled (uncertainty) Heterogeneity in consumption pattern not included Freezing not included, nor raw meat products ajority of cases from wild boar (1.97//y from 0.6 animals) compared to pigs from non-controlled housing (1.56//y from 114 animals) Our Trichinella QRA is a data-dense model and its outcomes seem in close agreement with observed incidence data Illegal or improper practices are impossible to model Under approved controlled housing, Trichinella testing is not adding any value to protect human health Compulsory meat inspection of all game intended for human consumption is a logical step to further improve food safety regarding Trichinella Given absence of positive findings in large numbers of pigs from controlled housing in preceding years, testing only 10% of animals is not meaningful Acknowledgements Arno Swart Joke van der Giessen Arie Havelaar Katsuhisa Takumi Ewa Bilska-Zając Anne ayer-scholl P C = c = f v, l = Y j + 1 l i! n E k=1 x k! 2 n E k=1 x k Thank you! c 1 c i=1 c p i Y i p j

Muscle distribution of Trichinella larvae in naturally infected pigs

Muscle distribution of Trichinella larvae in naturally infected pigs Różycki M. 1, Bilska-Zając E. 1, Chmurzyńska E. 1, Karamon J. 1, Wisniewski J. 2, Nowicki M. 2,Antolak E 1., Prochniak M. 1, Cencek