A Bayesian decision network model for analyzing biosecurity risk: Using a test-action biosecurity risk framework to develop a decision-theoretic model of white spot syndrome virus (WSSV) import risk for Hawai'i shrimp aquaculture

A "test-action" biosecurity risk framework was developed that translates biosecurity decisions into tests and actions for the purpose of analyzing biosecurity risk. From a decision-theoretic point of view, decisions are viewed as having action aspects that reduce consequences and/or test aspects that gather information. This perspective on decision-making offers an accounting method for biosurveillance measures, particularly the value of information resulting from test decisions. The framework was used to fulfill the research objectives for investigating WSSV import risk associated with frozen commodity shrimp (FCS): (1) development of a Bayesian decision network (BDN) to model WSSV import risk, (2) determining the "best" policy networks, and (3) estimating the value of biosurveillance for mitigating WSSV import risk.; A BDN was created based on the test-action biosecurity risk framework to model the impact of WSSV biosecurity policies, including a national movement restriction, biosurveillance, and specific pathogen free (SPF) zoning on FCS retail and shrimp aquaculture industries. The expected combined retail and farm profit was estimated at {dollar}60.04M. Based on the results of the WSSV import risk BDN simulation experiments, Hawaii farm loss due to WSSV was estimated at {dollar}2.91M. The best biosecurity policy, valued at {dollar}12.21M, would be a national movement restriction which limited the import of FCS products to WSSV-negative regions. The best state-level policy, valued at {dollar}4.62M, would be the establishment of a statewide SPF zone which required retailers to purchase SPF shrimp products from local Hawaii shrimp farmers. In light of the challenges of implementing a national movement restriction and current Hawaii SPF shrimp production levels, an SPF farm-zone on Oahu could be viewed as an efficient biosecurity policy that would increase the overall impact by {dollar}1.31M. Biosurveillance tradeoffs resulted in an increase in farm profit at the expense of retail losses.; The test-action biosecurity risk framework is a general approach to analyzing biosecurity problems which can be broken down into test and action decisions and where the pathways of exposure are known. The results of the BDN experiments contributed to a preliminary WSSV import risk analysis and served as a demonstration of the framework.