Transcript Risk Analysis in Aquaculture - Middle East

Risk Analysis in Aquaculture
Workshop for
OIE National Focal Points for Aquatic Animals,
Byblos, Lebanon, 12–14 August 2013
Edgar Brun
OIE Collaborating Centre on Epidemiology and
Risk Assessment for Aquatic Animal Diseases
Atlantic Veterinary
College, Canada
Outline
Definitions
 Why do risk analysis
 Basic principals
 Constraints
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What is risk analysis
An objective, systematic, standardized and
defensible method of assessing the likelihood of
negative consequences occurring due to a proposed
action or activity and the likely magnitude of those
consequences
Or…
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a model building process aiming to identify,
describe, manage and communicate a risk
a tool for science-based decision-making (manage
alternatives)
a tool for how to deal logically with uncertainty
and incomplete knowledge
What is «risk»
Risk in a daily language
 the chance of something going wrong
 any hazardous entity likely to cause injury, damage,
or loss

is subjective (relative to our mind and culture)
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is “invented” to understand and cope with dangers
and uncertainties of life
Risk in epidemiology
Risk is the probability that an event will occur with a
(generally) unfavorable outcome, in a specified time
interval
(Last, 2000)
Risk in Risk Analysis
means the likelihood of the occurrence and the likely
magnitude of the biological and economic
consequences of an adverse event or effect to animal
or human health
Risk = probability x consequence
Aquatic Animal Health Code (2012)
Event tree/Biological pathway
A “dissection” of the “risk-question” into a graphic
diagram (model) showing a step by step pathway of all
physical and biological events required for the hazard
to occur.
Each step (event) can be dedicated a likelihood of
occurring
Exampel; The biological pathway
Estimate the risk of one or more salmon smolt deriving
from a Gyrodactylus salaris infected watercourse, to
ascend neighbouring rivers still carrying viable
parasites
1. Smolts descending the home river (N)
2. Smolts infected when leaving home river
Photo TAMo
3. Smolts swimming towards a neighbouring river
4. Smolts swimming up a neighbouring river
5. Ascending smolts still infected when swimming up (n)
“Total uncertainty”
“Lack of certainty” exists whenever your knowledge or
understanding of an event, consequence, or likelihood is
inadequate or incomplete.

Uncertainty
● due to limited knowledge
● imprecise measurements
● can be reduced
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Variability
● normal variation
● can be measured and explained
● can not be reduced
Lack of differentiation may lead to inadequate or incomplete
knowledge or understanding of the results
Uncertainties are described by
distributions
Beta(2, 100)
40
35
30
25
20
15
10
5
70
60
50
40
30
20
10
0
0
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Depicted in a xy-diagrams;
x= any value for the variable
y = probability for occurring
Describes the likelihood of a
given outcome of a stochastic
variable (a stochastic process)
-10
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Values in Thousandths
5.0%
3.53
90.0%
5.0% >
46.11
Sensitivity analysis
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Testing the relative importance of the different
variables (steps) in the pathway
- how and to what extent the various variables
and their related uncertainty in a model affects the
final result
Why do we need to do risk analysis in
aquaculture
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Risk to farmed aquatic animals
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Introduction of pathogens through import (OIE/WTO)
Where to establish new sites
Awareness of hazards (new/most important)
Identify populations/areas most at risk
Identify farms most likely to be infected
Welfare
Risk to the environment
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Pathogen exchange between farmed and wild
Genetic impact of escapees
Invasion of non-naïve species
Pollution from aquaculture or to aquaculture
Why do we need to do risk analysis in
aquaculture
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Risk to humans
● Food safety and public health (Codex)
● Social risks
 Socio-economic (employment)
 Reputation
 Welfare
FAO (2008): Understanding and applying risk analysis in aquaculture
Basic principals
Four basic components in risk analysis
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Hazard identification
Risk assessment
Risk management
Risk communication
Hazard identification
The process of identifying which hazard(s) that could
potentially produce which adverse consequences
● close collaboration with risk assessors and mangers
for a precise definition of the task to be assessed
(face to face meetings)
Hazard identification (characterization)
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What do we know about the disease
● Agent characteristics, clinics, treatment,
transmission etc.
Diagnostic tests
Distribution in exporting country
Any surveillance in exporting country
How sure are we of the situation in our own
country/farm
Risk assessment
the process of evaluating
●
the likelihood that a defined hazard will be
introduced, established, and spread
●
estimating the biological and economic
consequences
Risk assessment (4 steps)
1. Release assessment – determine the likelihood that
a hazard will be introduced (transferred) through a
planned action (e.g. with a consignment)
2. Exposure assessment –determine the likelihood that
a transferred hazard will be able to establish (spread)
in its new environment
For release and exposure we need a pathway
1. Smolts descending the home river (N)
2. Smolts infected when leaving home river
3. Smolts swimming towards a neighbouring river
4. Smolts swimming up a neighbouring river
5. Ascending smolts still infected when swimming up (n)
6. Viable parasites able to infect susceptible species
Risk assessment
3. Consequence assessment – quantify the possible
biological and economic damage the established
hazard may cause
4. Risk estimation – integrating the estimation of the
probability of release and exposure events with the
results of the consequence assessment to produce an
estimate of the overall risk of the event occurring.
Qualitative vs Quantitative RA
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Qualitative RA (risk estimates in ”high”, “moderate” ”little”,
”negligible ”)
● Often a first choice
● Quick, low requirement for data
● Low level of precision , no measure for uncertainty
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Quantitative RA (risk estimates in numbers)
● Deterministic- model: using fixed (average) values
 quicker, moderate quantitative data need
 low precision for uncertainty
● Probabilistic-model: using distributions for uncertainty and
variability
 good estimates for uncertainty, sensitivity analysis
 high demand for resources (time, money and competence)
Qualitative risk estimates
Rivers
 River 1
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N
Mean 95%CI Max
13,000
65,000
130,000
200,000
0.1
0.5
1.0
1.5
0-1
0-4
0-7
0-10
13,000
65,000
130,000
200,000
0
0-0
0.0002 0-0
0.0003 0-0
0.0004 0-0
p(0)
5
11
17
25
91.9 %
76.5 %
69.2 %
65.7 %
0
2
2
4
100.00 %
99.98 %
99.97 %
99.97 %
River 2
Qualitative risk estimates
0.80
0.70
0.69
Probability
0.60
0.50
0.40
0.30
0.20
0.09 0.06
0.05 0.03 0.02 0.02
0.01 0.01 0.005 0.003 0.004
0.10
0.00
0
1
2
3
4
5
6
7
8
9
10
Number of infected smolts
P(infected smolts ascending the river>0)=0.31
>10
Quantitative risk estimates (Risk matrix)
Risk management
The handling of the results from the risk assessment
and implementing necessary means to reduce either
the likelihood of realization (introduction and
spreading) and/or the consequences of it
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ensure a balance between a country's desire to minimise
the likelihood or frequency of disease incursions and
their consequences and its desire to import commodities
and fulfil its obligations under international trade
agreements (OIE).
Risk management
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Deals with policy related to risk
● Acceptable level of risk
● Recognition of unacceptable risk and that some "risky"
actions cannot be managed and therefore should not
be permitted under any circumstance
● Application of the precautionary approach
A risk assessment may give more than one result
 Alternative risk management measures achieving the
required level of protection are equally acceptable
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Benefits ?
Risk communication
A risk analysis strives for
objectivity, but
contains elements of subjectivity
transparency is essential.
Risk communication
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A continuous open and transparent process where all
stakeholders are consulted, results incl assumptions and
uncertainty, and management measures communicated.
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Should begin at the start of the risk analysis process and
continue throughout
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Peer review of the risk analysis is an essential component
of risk communication for obtaining a scientific critique aimed
at ensuring that the data, information, methods and
assumptions are the best available
How likely?
How serious?
What can go
wrong?
Hazard
identification
What can we do
about it?
Risk
assessment:
-release
-exposure
-consequence
-risk estimation
risk communication
Risk
management:
-risk estimation
-option
evaluation
-implementation
-monitoring &
review
From the Aquatic Animal Health Code
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OIE has its focus on trade (IRA), but no a single
method of import risk assessment has proven
applicable in all situations
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The process needs to include an evaluation of the
aquatic animal health service, zoning and
regionalization, and
surveillance systems
in place in the exporting
country
Constraints in risk analysis
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Technical
● Resources (competence, time, money…)
● Communication (internal/external)
Scientific
● Definition of the question
● Data
Usefulness
● Credibility (is the question answered, is the model correct)
Management
● How to handle lack of information
● Competence to act
Communicative
● Terminology
● Transparency
● Results
 Assumptions – limitations imbedded in the model
Final remarks
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International aquaculture has a number of
biosecurity and physical concerns that pose risks and
hazards to both its own development and
management, and to the aquatic environment and
the human society
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RA in aquaculture should be used to assess both risk
to society and environment and from society and
environment to aquaculture
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RA can be used to improved sustainability,
profitability and public’s perception of the sector
Thank you for your attention