Priority setting of emerging zoonoses

1
Priority setting of emerging zoonoses

• Marieta Braks, Ph.D.
• and
• Prof. A. Havelaar, M. Toutenel and F. van Rosse
• Laboratory for Zoonoses and Environmental
  Microbiology
• RIVM, the Netherlands
• Discontools, Brussels
• 20 October 2008

2
Contents

• Emerging zoonoses
• Priority setting
• Priority setting of emerging zoonoses

3
From infectious diseases to emerging zoonoses

• List of 1415 infectious pathogens for humans
• 217 Viruses
• 538 Bacteriae and Rickettsiae
• 307 Fungi
• 66 Protozoa
• 287 Helminths
• 863 (61) are zoonotic,
• 175 emerging pathogens and of these 75 are
  zoonotic

(Taylor et al, Phil.Trans. R. Soc. London B.
Biol. 2001)
4
Priority setting

• Too much to study all in detail, choices are
  necessary
• Comparing risks is not impossible or immoral,
  but it is very difficult --more so than either
  supporters or detractors of the practice seem to
  realize
• Adam Finkel, Comparing Risks Thoughtfully

5
Priority setting, choices

• Multi-dimensional problem
• Technical information ánd value judgements
• Interaction between researchers and policy makers
  c.q. general population
• One time or continuous?
• Simplicity vs. precision
• Transparancy and information management

6
Priority setting, possibilities

• Consensus
• Simple but not very transpare
• Poor repeatability
• Semi-quantitative
• Transparant but arbitrary
• Better repeatability
• Quantitative
• Transparant and objective
• Knowledge management

7
Approach to priority setting EmZoo

• Selecting agents
• Literature and expertise consortium
• Establishing criteria (risk aspects)
• Limited number
• Expressed in natural units
• Consortium with steering committee
• Operationalising criteria
• 4-5 classes (point estimate and range)
• Evaluation of all agents simple decision rules
  current situation
• Consortium
• Weighing criteria
• Panel session with policy makers
• Ranking of hypothetical zoonoses according to
  perceived threat
• Data analysis and reporting
• Information management system
• Improve data
• Update information
• Scenario analysis

8
Criteria

1. Probability of introduction
2. Spread in animal reservoir
3. Economic costs, animals
4. Transfer from animals to man
5. Spread in human reservoir
6. Severity of human illness
7. Case-fatality ratio human
8. Economic costs, human
9. Perception

9
Semi-quantitative approach
Semiquantitative scores Semiquantitative scores Semiquantitative scores Semiquantitative scores Semiquantitative scores Semiquantitative scores
Criteria X1 X2 X3 X4 X5 X6 X7 X8 X9 Sum
High threat 5 4 4 4 4 4 5 4 4 38
Low threat 1 1 1 1 1 1 2 1 1 10
Ehrlichia chaffeensis 3 3 1 1 1 3 3 2 2 19
Bartonella henselae 5 2 1 1 1 1 3 1 1 16
Brucella melitensis 4 2 3 2 1 2 2 3 2 21
Brucella suis 4 2 3 1 1 2 3 3 1 20
Burkholderia pseudomallei 2 4 1 1 1 3 4 1 1 18
Campylobacter spp. 5 4 1 1 2 1 2 3 2 21
10
Operationalising criteriaeconomic costs ANIMAL

• 4 classes, decision rules
• Low no illness in Dutch animal husbandry, or
  control is possible at farm level
• Average illness is possible in Dutch animal
  husbandry and control at regional level
• High illness is possible in Dutch animal
  husbandry and control at national level
• Very high illness is possible in Dutch animal
  husbandry and export is reduced for more than ½
  year
• Quantification
• Low lt 10 M per year, point estimate 5 M pyr
• Avergae 10 100 M per year, point estimate 50
  M pyr
• High 100 1000 M per year, point estimate 500
  M pyr
• Very high gt 1000 M per year, point estimate
  5000 M pyr

11
Panel session

• Obtain information for weighing criteria
• Weights reflect policy choices of the Dutch
  government
• Ranking of hypothetical zoonoses
• 6 sets van 7 zoonoses and 1 trainings set
• Arrange from least to most threatening
• Individual judgement
• Written repetition after 2 weeks (2 sets of 7)

12
Quantitative approach
Weights 0,50 -0,31 0,41 0,29 -0,24 0,23 0,62 0,50 0,29

Criteria X1 X2 X3 X4 X5 X6 X7 X8 X9 Sum

High threat 0,50 -0,04 0,41 0,29 -0,03 0,23 0,62 0,50 0,22 2,70
Low threat 0,00 -0,31 0,28 0,00 -0,24 0,01 0,00 0,34 0,00 0,09
Ehrlichia chaffeensis 0,03 -0,08 0,28 0,00 -0,24 0,08 0,03 0,40 0,07 0,56
Bartonella henselae 0,50 -0,11 0,28 0,00 -0,24 0,01 0,03 0,34 0,00 0,81
Brucella melitensis 0,25 -0,11 0,37 0,00 -0,24 0,02 0,00 0,45 0,07 0,81
Brucella suis 0,25 -0,11 0,37 0,00 -0,24 0,02 0,03 0,45 0,00 0,76
Burkholderia pseudomallei 0,00 -0,04 0,28 0,00 -0,24 0,08 0,31 0,34 0,00 0,74
Campylobacter spp. 0,50 -0,04 0,28 0,00 -0,09 0,01 0,00 0,45 0,07 1,19
13
Semi-quantitative vs quantitative approach
14
Results quantitative approach
15
Overall conclusions

• Priority setting is a multidimensional problem
• Ranking depends on the criterium used
• A quantitative and systematic approach is
  necessary
• Current data are not complete, but data needs can
  be prioritised
• Method is currently being validated and
  optimalised
• International collaboration will speed up the
  process