risk based sampling · risk based sampling a public health perspective from the netherlands...

Risk-based Sampling Perspective from Different EU and Non-EU Member States

Risk Based Sampling | May 2016 1

Jenny Scott: Senior Advisor to the Director of the Office of Food Safety at FDA’s Center for Food Safety and Applied Nutrition.

Akos Jozwiak: Vice-director at the Hungarian National Food Chain Safety Office

Annemarie Pielaat: Senior researcher at the Dutch Institute for Public Health and the Environment (RIVM)

The presenters ● Akos Jozwiak:

– Head of the coordination working group on planning of sampling plans, supervising different sampling programs from soil and plant protection to plant and animal health, feed and food domains.

– Presentation: theoretical background of the planning process at central authority level with practical and organizational examples, problems identified and solutions provided recently.

● Jenny Scott:

– Technical lead of the team that developed the new Preventive Controls for Human Food rule, with a risk-based approach to control of food hazards.

– Presentation: risk-based microbial sampling by industry as part of a food safety system. FDA’s approach to its risk-based sampling including data use. (prepared in conjunction with Dr. Yuhuan Chen (RA at FDA).

● Annemarie Pielaat:

– Project manager for different research projects in food safety RA.

– Presentation: Development of a risk based sampling program for the Netherlands Food and Consumer Product Safety Authority (NVWA)


Risk Based Sampling

A public health perspective from The Netherlands

Annemarie Pielaat

Jurgen Chardon, Lucas Wijnands, Ellen Delfgou, Angelina Kuijpers, Aarieke de Jong, Eric Evers

Risk Based Sampling | May 2016

Introduction

● Netherlands Food and Consumer Product Safety Authority (NVWA)

● Monitoring program occurrence microorganisms on food products

● Insight in public health risk caused by foodborne pathogens


Optimization of program through risk based sampling

Approach

● Optimization of monitoring foodborne pathogens for public health risk estimates

● Input variables:

– Prevalence, concentration microorganisms

– Consumption figures food products & food handling by consumers

– Disease burden

– Sampling costs

● Definition of Risk based sampling

*DALY: Disability Adjusted Life Year (Havelaar et. al, 2012) is a consistent, quantitative measure to compare the disease burden of different foodborne pathogens


Distribute the NVWA sampling capacity over retail products proportional to their contribution to the DALY’s*

Methodology


Distribute the NVWA sampling capacity over retail products proportional to their contribution to the DALY’s

Optimizing criterion: (C * D) / B(A) expressed as costs per DALY

A. Exposure assessment Pathogen prevalence and concentration at time of purchase, food preparation and amount consumed

B. Attribution to DALY’s Distribute DALY’s on pathogen-product group over products proportional to exposure

C. Sampling Initial prevalence to assess the number of samples needed for each product

D. Costs Personnel and analysis costs

Case studies

Initial pathogen product combinations of interest to NVWA

● Salmonella on pork meat

● Campylobacter on pork meat and on poultry meat

● Toxoplasma on pork meat

● Shiga toxin-producing Escherichia coli (STEC) O157 on beef


Exposure Assessment

● Based on swift QMRA tool with deterministic calculations (Chardon and Evers, 2016)

● Changes in numbers of micro-organisms on food products

Retail Storage Preparation Exposure


Chardon and Evers


Using fit-for-purpose models from sQMRA • Time / temp dynamics • D/z inactivation models • …

P re - retail processing

F ood product

- Consumption data

- prev/conc pathogens

-reduction due to

smoking/salting/drying/cooking/heating

Consumer storage

- fractions

room/fridge/freezer

- storage times

- growth/inactivation

Cross cont - amination

- CC fractions

- CC transfer rate

Heating - Raw consumed products

- Heating Model

- fraction meat balls / raw / medium / done

- D/z inactivation data

- heating time and temp

Exposure No. contaminated portions at consumption and total no. of micro-organisms ingested (pop.n year-1)

Attribute DALY’s to Exposure


Food product Exposure* DALYs

Pork, chops, rib 1.6E+03 6.1E+01

Ham, raw 1.1E-01 4.3E-03

Bacon, smoked 1.9E-02 3.7E-03

Sausage, BBQ 1.8E+02 6.9E+00

… … …

*No. contaminated portions at consumption and total number of micro-organisms ingested (pop.n year-1 )

Sampling


● NVWA does not monitor DALYs but prevalences for pathogen-product combinations

Mean pathogen prevalences (%) in the Netherlands in retail 2010-2013.

Pathogen / food animal

combination

Fresh

meat

Meat

product Source

STEC beef&veal 1,31 3,88 A

STEC mutton/lamb 6,69 3,44 A

Salmonella pork 0,97 1,29 A

Campylobacter pork 0,37 0,16B A

Toxoplasma pork 0,90C 0,90C Zomer et al. (2014)

Campylobacter chicken 27,38 11,60 Zomer et al. (2014)

A: data from the NVWA. B: no measurements available, calculated using ratio for chicken

(0,37*11,6/27,38); C: based on serological prevalence in slaughter house.

Sampling ● Link Sampling with

Prevalence

● How many samples are needed to estimate prevalence within defined uncertainty

● Basic principle:

Numbers based on

one positive sample

Number of samples with number of positives

Uncertainty about prevalence estimate slowly


PATH.-PRODUCT RETAIL PRODUCT NO PORTIONS DALYs PREVALENCE

Campy-pork Pork, spare rib (SH 786) 2,5E+06 0,0 0,37%

Campy-pork Pork, fricandeau 1,1E+07 0,0 0,37%

Campy-pork Pork, silverside 5,7E+07 0,1 0,37%

Campy-pork "rotterdammertje" 7,5E+05 0,1 0,16%

Campy-pork Salami 2,3E+08 29,7 0,16%

Campy-pork "Worst, met" 5,9E+07 8,1 0,16%

Campy-poultry Chicken n.s. 5,0E+07 15,3 27,38%

Campy-poultry Chicken, wing 2,7E+07 16,2 27,38%

Campy-poultry Chicken, leg 4,6E+07 46,4 27,38%

Salm-pork Dried sausages n.s. 4,8E+07 5,3 1,29%

Salm-pork Cervelaat 2,7E+08 13,2 1,29%

Salm-pork "rotterdammertje" 7,5E+05 0,1 1,29%

STEC-beef Salami 2,3E+08 0,9 3,88%

STEC-beef Roasted meat, cold n.s. 1,3E+07 0,0 3,88%

STEC-beef Filet americain 3,2E+08 12,8 3,88%

Toxopl-pork "Worst, paling" 4,8E+07 0,0 0,90%

Toxopl-pork Dried sausages n.s. 4,8E+07 76,4 0,90%

Toxopl-pork Cervelaat 2,7E+08 185,0 0,90%

Toxopl-pork "Worst, chorizo" 2,0E+07 28,3 0,90%

… … … … …

Exposure

Sampling


PATH.-PRODUCT RETAIL PRODUCT NO PORTIONS DALYs PREVALENCE

Campy-pork Pork, spare rib (SH 786) 2,5E+06 0,0 0,37%

Campy-pork Pork, fricandeau 1,1E+07 0,0 0,37%

Campy-pork Pork, silverside 5,7E+07 0,1 0,37%

Campy-pork "rotterdammertje" 7,5E+05 0,1 0,16%

Campy-pork Salami 2,3E+08 29,7 0,16%

Campy-pork "Worst, met" 5,9E+07 8,1 0,16%

Campy-poultry Chicken n.s. 5,0E+07 15,3 27,38%

Campy-poultry Chicken, wing 2,7E+07 16,2 27,38%

Campy-poultry Chicken, leg 4,6E+07 46,4 27,38%

Salm-pork Dried sausages n.s. 4,8E+07 5,3 1,29%

Salm-pork Cervelaat 2,7E+08 13,2 1,29%

Salm-pork "rotterdammertje" 7,5E+05 0,1 1,29%

STEC-beef Salami 2,3E+08 0,9 3,88%

STEC-beef Roasted meat, cold n.s. 1,3E+07 0,0 3,88%

STEC-beef Filet americain 3,2E+08 12,8 3,88%

Toxopl-pork "Worst, paling" 4,8E+07 0,0 0,90%

Toxopl-pork Dried sausages n.s. 4,8E+07 76,4 0,90%

Toxopl-pork Cervelaat 2,7E+08 185,0 0,90%

Toxopl-pork "Worst, chorizo" 2,0E+07 28,3 0,90%

… … … … …

SAMPLES

540

540

540

1250

1250

1250

6

6

6

153

153

153

50

50

50

220

220

220

220

…

k n d

1 1250 0,16%

1 540 0,37%

1 220 0,90%

1 205 0,97%

1 153 1,29%

1 151 1,31%

1 56 3,45%

1 50 3,85%

1 28 6,67%

1 16 11,11%

1 6 25,00%

Costs ● NVWA budget: e.g. €225,000.-

● Catch maximum number of DALYs for minimum budget

● Optimization criterium:

● Sort on Costs per DALY (min max)


What is the best sampling strategy from a public health perspective within this budget?

Pathogen/ Product

Source Costs*

Campylobacter

Fresh meat Pork 17,-

Fresh meat Poultry 50,-

Meat product Pork 15,-

Meat product Poultry 30,-

STEC

Fresh meat Beef/Veal 25,-

Meat product Beef/Veal 37,-

Fresh meat Mutton/Lamb 52,-

Meat product Mutton/Lamb 35,-

Salmonella


Meat product Pork 21,-

Toxoplasma


* € Per sample, incl admin #Samples • Costs DALYs

Results

Top 26

pathogen-product combinations

for sample analysis

maximised for DALYs as measure for

public health risk


TOP ID foodnum pathogen/matrix VCP-product DALY's Prevalentie

Aantal

monsters

Totale

kosten

Kosten/

DALY

Cumulatieve

kosten

Cumulatieve

aantal

monsters

1 149 0863 1. Campy-kip Kip filet 579,28 27,38% 6 € 505 8,72E-01 € 505,0 6

2 146 0860 1. Campy-kip Kip poot 46,41 27,38% 6 € 505 1,09E+01 € 1.010,1 12

3 147 0861 1. Campy-kip Kip drumstick 41,69 27,38% 6 € 505 1,21E+01 € 1.515,1 18

4 155 0870 1. Campy-kip Kip braadstuk 39,50 27,38% 6 € 505 1,28E+01 € 2.020,1 24

5 151 0865 1. Campy-kip Kip half 21,56 27,38% 6 € 505 2,34E+01 € 2.525,2 30

6 150 0864 1. Campy-kip Kip heel 17,22 27,38% 6 € 505 2,93E+01 € 3.030,2 36

7 145 0859 1. Campy-kip Kip vleugel 16,25 27,38% 6 € 505 3,11E+01 € 3.535,2 42

8 144 0857 1. Campy-kip Kip n.s. 15,26 27,38% 6 € 505 3,31E+01 € 4.040,3 48

9 148 0862 1. Campy-kip Kip borst met bot 13,34 27,38% 6 € 505 3,79E+01 € 4.545,3 54

10 157 2667 1. Campy-kip Kip reepjes 11,54 27,38% 6 € 505 4,37E+01 € 5.050,3 60

11 156 0871 1. Campy-kip Kip karbonade 8,57 27,38% 6 € 505 5,89E+01 € 5.555,3 66

12 154 0868 1. Campy-kip Kip TV stick 6,48 27,38% 6 € 505 7,79E+01 € 6.060,4 72

13 500 0970 2.Toxopl-varken Salami 374,59 0,90% 220 € 30.283 8,08E+01 € 36.343,4 292

14 497 0966 2.Toxopl-varken Cervelaat 185,02 0,90% 220 € 30.283 1,64E+02 € 66.626,4 512

15 502 0972 2.Toxopl-varken Worst snij 145,08 0,90% 220 € 30.283 2,09E+02 € 96.909,4 732

16 208 0989 2. Salm-varken Ham coburger 28,92 1,29% 153 € 6.209 2,15E+02 € 103.118,6 885

17 265 0970 2. Salm-varken Salami 26,74 1,29% 153 € 6.209 2,32E+02 € 109.327,9 1038

18 377 1012 2. STEC-rund Filet americain 12,78 3,88% 50 € 3.255 2,55E+02 € 112.583,1 1088

19 501 0971 2.Toxopl-varken Worst met 102,26 0,90% 220 € 30.283 2,96E+02 € 142.866,1 1308

20 496 0965 2.Toxopl-varken Worst gedroogd n.s. 76,41 0,90% 220 € 30.283 3,96E+02 € 173.149,1 1528

21 153 0867 1. Campy-kip Kip soep 1,12 27,38% 6 € 505 4,50E+02 € 173.654,2 1534

22 262 0966 2. Salm-varken Cervelaat 13,21 1,29% 153 € 6.209 4,70E+02 € 179.863,4 1687

23 159 0869 2. Campy-kip Kip rollade 1,85 11,60% 16 € 906 4,89E+02 € 180.769,8 1703

24 443 0989 2.Toxopl-varken Ham coburger 55,56 0,90% 220 € 30.283 5,45E+02 € 211.052,8 1923

25 267 0972 2. Salm-varken Worst snij 10,25 1,29% 153 € 6.209 6,06E+02 € 217.262,0 2076

26 266 0971 2. Salm-varken Worst met 7,30 1,29% 153 € 6.209 8,51E+02 € 223.471,3 2229

Product*

*Net number of samples: 1894

*

Trend analysis

● Minimum no. samples in two consecutive sampling events (n1=n2) to identify a significant difference in prevalence (d1 and d2) with certain probability (power of the test)

H0: d1 = d2

Ha: d1 ≠ d2

● Power: P(reject H0 in favour of Ha when Ha is true) depends on:

– Actual difference between d1 and d2

– Significance level, α and

– Number of samples (n)


Trend analysis


d1

d2

d2

d2

d2

d1

d1 d1

Conclusion

The Netherlands:

● If €225,000.-

● n ~2000 samples over ~20 different meat products

● Top 12: Campylobacter on different poultry products

– Chicken filet no. 1 product

● Not sufficient for trend analysis in two consecutive years

– Power of the test ≤ 55%

● Consistent iterative implementation of risk based sampling plan

– Monitor pathogen prevalence based on public health risk

– Adapt intervention programs based on public health risk

– Trend analysis


Discussion

● Extend for other pathogen-product combinations

– Next important DALY

● Update prevalence estimates

– Use of molecular methods for monitoring? (reduce costs)

● Improve exposure assessment parameter estimates

– Pathogen survival on meat (STEC on beef)


risk based sampling · risk based sampling a public health perspective from the netherlands...

Documents