“An ounce of prevention is worth a pound of cure.” [ancient proverb] Henry de Bracton, De Legibus, 1240

Risk Assessment “How likely is it to go wrong?” The process of evaluating the likelihood that a “potential hazard” will gain entry into the importing country and Estimating the biological and economic consequences of its entry, establishment and/or spread.

Import Risk Analysis Framework

Simplified Hypothetical Risk Analysis Process 5. Identify Stakeholders. 6. Inform Stakeholders of Project & Seek Comments on Preliminary Hazard Identification 7. Conduct the Detailed Hazard Identification 8. Conduct the Risk Assessment  Release assessment  Exposure assessment  Consequence assessment  Risk estimation

Risk Assessment Consists of four interrelated steps: release assessment exposure assessment consequence assessment risk estimation

Risk Assessment Risk Assessments can be: Qualitative (e.g., “high”, “medium,” “low”) or Quantitative (e.g., 1 outbreak of disease/per 100,000 tonnes of imported fish/year) Both processes are equally valid - therefore one is not innately better than the other. Note that one short-coming of qualitative risk assessment is that it is difficult to incorporate the effect of volume of trade into the risk estimate.

Qualitative Risk Analysis Release and Exposure Assessment use various terms to describe the likelihood of an event occurring. Example with 5 terms: High: Event would be expected to occur Moderate: There is less than an even chance of the event occurring Low: Event would be unlikely to occur Very low: Event would rarely occur Negligible: Chance of event occurring is so small that it can be ignored in practical terms

Risk Assessment Preparation of scenario trees aid in outlining pathways and estimating likelihoods for release and exposure Note that risks are assessed individually for each hazard identified

Release Assessment If we bring in the commodity, how likely is it that the pathogen will enter with it? Involves a detailed discussion of the biological pathways necessary for the commodity to become infected and estimating the likelihood of these events occurring.

Release Assessment This means consideration of: biological factors infectivity virulence and stability route(s) of infection means of transmission, susceptibility of animals outcomes of infection, etc.

Release Assessment This means consideration of: country factors evaluation of exporting country’s Competent Authority presence of surveillance, control & eradication programs zoning prevalence and incidence animal demographics, etc. etc.

Release Assessment This means consideration of: commodity factors life cycle stage to be moved ease of infection (e.g., host resistance) proposed source storage and transport methods, etc. The analysis is concluded if the likelihood of release is negligible

Simplified Release Scenario Tree for for a Virus

A Matrix of “Rules” for Combining Descriptive Likelihoods NegligibleVery LowLowModerateHigh Negligible Very LowLowModerateHigh ModerateNegligibleVery LowLow NegligibleVery Low Very Low Negligible Negligible From the various pathways steps in a scenario tree, this table can be used to calculate the overall likelihood for the release estimate and the exposure estimate.

Example Calculation Based on the Hypothetical Pathway for Viral Release StepQualitative Descriptor Product of Likelihoods L1 – Selection of Infected Spawners Low L2 – Selection of Infected PLs High…>Low L3 – Selection of Infected Subsample High………....…> Low L4 – Pathogens not detected by genomic testing (and shipped to Cook Islands) Very Low……………….…….> Very Low Assumptions: prevalence in broodstock is low transmission from female to PL is high diagnostic test has very high sensitivity

Exposure Assessment Now that the pathogen has successfully gained entry to the country, what are the chances than susceptible native or cultured stocks will be exposed to it? Involves a detailed discussion of the biological pathways necessary for aquatic animals in the importing country to become infected

Exposure Assessment For each potential hazard: Describe the biological pathway(s) necessary for exposure of aquatic animals in the importing country Estimate the likelihood of these exposure(s) If the likelihood of exposure is negligible, the risk assessment for the hazard is completed. Note that “exposure” does not imply “infection” of the exposed stock

Exposure Assessment Relevant factors include: Biological factors Country factors Commodity factors

Simplified Exposure Scenario Tree for a Virus

A Matrix of “Rules” for Combining Descriptive Likelihoods NegligibleVery LowLowModerateHigh Negligible Very LowLowModerateHigh ModerateNegligibleVery LowLow NegligibleVery Low Very Low Negligible Negligible Note that this is the same table used for estimating pathogen release

Consequence Assessment “What would be the consequences of its going wrong?” Identify the consequences of the pathogen’s entry, establishment & spread (i.e. potential biological, environmental & economic impacts) Estimate the likelihood of these potential consequences occurring.

Consequence Assessment Consequences can be both direct & indirect: Direct consequences include: outcome of infections in local fish stocks (morbidity, mortality, production losses, public health impacts, environmental impacts, etc.) Indirect consequences, include: economic considerations such as control & eradication costs, compensation, surveillance costs, potential trade losses, etc.

Consequence Assessment : Qualitative Rankings Example 5 category system: Catastrophic High Moderate Low Negligible Terms are defined in terms of the biological and economic consequences and the difficulty of control

Consequence Assessment: Qualitative Rankings Catastrophic: Disease would significantly harm economic performance at an industry level &/or cause serious & irreversible environmental harm. High: Disease would have serious biological consequences (e.g. high mortality or morbidity) & would not be amenable to control or eradication. It could significantly harm economic performance at an industry level &/or cause serious environmental harm. Moderate: Diseases would have less pronounced biological consequences & may be amenable to control or eradication. It could harm economic performance at an industry level &/or cause some environmental effects, which would not be serious or irreversible.

Consequence Assessment : Qualitative Rankings Low: Diseases would have mild biological consequences & would normally be amenable to control or eradication. Effects on economic performance & the environment would not be serious or irreversible. Negligible: Diseases would have no significant biological, ecological or economic consequences & would not require control or eradication.

Steps in Consequence Assessment Estimate the likelihood that at least one animal becomes infected. Identify the biological, environmental and economic consequences associated with the entry, establishment or spread of the hazard and their likely magnitude. Estimate the likelihood of the occurrence of these consequences. Note that The first consequence of interest is the successful infection of at least one animal..

Consequence Assessment Note that there are various methods for estimating the magnitude and likelihood of a consequence, and for combining consequences. “Outbreak scenarios” can be useful in estimating likelihood and magnitude. Similarly, consequences can be examined at different levels: farm/village, district, regional, national. In some cases it may be necessary to have the assistance of experts in economics and social sciences to estimate the potential magnitude of consequences.

Risk Estimation Integrates the results of release assessment, exposure assessment & consequence assessment to produce an overall estimate of the risk posed by the hazard. First we combine the likelihood or release with the likelihood of exposure, then we combine the result with the estimated level of consequence.

Combining Likelihood of Release and Probability of Exposure NegligibleVery LowLowModerateHigh Negligible Very LowLowModerateHigh ModerateNegligibleVery LowLow NegligibleVery Low Very Low Negligible Negligible Likelihood of Exposure Likelihood of Release

Estimating Total Risk posed by a Hazard NegligibleLowModerateHighCatastrophic HighNegligible Risk Low Risk Moderate Risk High Risk Extreme Risk ModerateNegligible RiskLowRisk Moderate Risk High Risk Extreme Risk LowNegligible Risk Very Low RiskLowRisk Moderate Risk High Risk Very LowNegligible Risk Negligible Risk Very Low RiskLowRisk Moderate Risk Negligible Risk Negligible Risk Negligible Risk Negligible Risk Negligible Risk Estimated Likelihood of Release & Exposure Estimated Consequence of Release & Exposure

Practical Example: Risk Assessment for WSSV in Giant River Prawn Release Assessment circumstantial evidence indicates Fijian stock unlikely to be exposed maintained in relative isolation since importation from Tahiti in 1977 No reports of WSSV from Tahiti Fijian stock believed never to have been in contact with penaeid shrimp no evidence that wild or cultured penaeids in Fiji have been exposed to WSSV Therefore, likelihood of WSSV being present in the stock of origin is LOW

Practical Example: Risk Assessment for WSSV in Giant River Prawn Exposure Assessment If PL introduced to Rarotonga are infected with WSSV, the likelihood of the pathogen escaping the culture facility & gaining access to susceptible populations is estimated as LOW, because: animals will be maintained in covered concrete tanks, making escape unlikely effluent waters will not enter natural waters

Practical Example: Risk Assessment for WSSV in Giant River Prawn Consequence Assessment WSSV does not cause overt disease or mortalities in river prawn no penaeid culture in Cook Islands; thus any impact will be on natural stocks (which are very limited) potential exists for WSSV to become endemic, with possible negative impacts on future aquaculture development The consequences of this occurring were considered Moderate

Practical Example: Risk Assessment for WSSV in Giant River Prawn Estimating risk Likelihood of Release – Low Likelihood of Exposure – Low Likelihood of Release and Exposure – Low Estimate of Consequence – Moderate Estimate of overall risk - Moderate In this risk analysis, we were very conservative in combining likelihoods. Using the previous tables for combining likelihoods would give a total estimated risk as Very Low.

Key Points Risk Assessment is done individually for each hazard. If likelihood of release is negligible, the assessment stops. If it is non-negligible, we proceed to exposure assessment. If the likelihood of exposure is negligible, the assessment stops. If it is non-negligible, we proceed to consequence assessment. If the consequence is negligible, the assessment stops

Key Points If it is non-negligible, we proceed to risk estimation. Risk estimation gives us an estimate of the total risk posed by the hazard. Preparing scenario trees and pathways help the risk analyst to clarify thinking and to estimate release and exposure likelihoods. They are also useful for consequence assessment and in communicating the process and results of risk analysis to stakeholders.