Evidence suggests African swine fever virus (ASFV) may survive under conditions similar to those observed in transoceanic transport models. In a Swine Health Information Center (SHIC)-funded study, researchers developed a quantitative risk assessment model to estimate the probability that one or more corn or soybean meal ocean vessels contaminated with ASFV would be imported into the US annually. Ultimately, this model can be used to evaluate risk mitigation strategies and critical control points for inactivating ASFV during feed ingredient processing, storage, and transport, and contribute to the design and implementation of biosecurity measures to prevent the introduction of ASFV into the US and other ASFV-free countries. Study authors are Rachel A. Schambow, Fernando Sampedro, Pedro E. Urriola, Jennifer L. G. van de Ligt, Andres Perez, and Gerald C. Shurson.
The published, copyrighted study said the final estimate was conditionally based on five likelihoods: probability of initial ASFV contamination, ASFV inactivation during processing, ASFV inactivation during transport, recontamination, and ASFV inactivation while awaiting customs clearance at US entry. “What if” scenarios were used to explore their impact on risk.
The model estimated complete inactivation of ASFV after soybean extrusion or solvent extraction processes regardless of the initial ASFV contamination probability assumed. The value of recontamination was highly influential on the risk of one ASFV-contaminated soybean meal vessel entering the US. Using the current information available, results showed it would be certain that at least one vessel with ASFV-contaminated soybean meal would be imported once every 21 to ~1,500 years. When all raw corn was assumed to be contaminated and no recontamination was assumed to occur, median probability of one vessel with ASFV-contaminated corn entering the US was 2.02%, or once every 50 years. Days of transport, virus survival during transport, and number of vessels shipped were the most influential parameters for increased likelihood of a vessel with ASFV-contaminated soybean meal or corn entering the US.
The model helped to identify knowledge gaps that are most influential on output values and serves as a framework that could be updated and parameterized as new scientific information becomes available. Researchers propose the quantitative risk assessment model developed in this study be used as a framework for estimating the risk of ASFV entry into the US and other ASFV-free countries through other types of imported feed ingredients that may potentially become contaminated.
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