Mathematical model for viral depuration kinetics in shellfish: an useful tool to estimate the risk for the consumers

Enteric virus depuration from shellfish is a complex biological process that may be influenced by biological properties of the mollusc and/or virus species. On the basis of previous experimental data, a mathematical model was developed to characterize the kinetics of viral elimination during the depuration process. The experimental data consisted on twenty depuration trials, each with 60 kg of Manila clams (Venerupis philippinarum) and mediterranean mussels (Mytilus galloprovincialis) previously subjected to bioaccumulation with HAV or MNV-1 (as a surrogate for human norovirus), that were performed in an experimental depuration system during 7 days. It was observed that although viral loads decay along depuration, a residual viral load remains at the end of the process suggesting a decomposition of viral load in a diluted load (susceptible of depuration) and a non-diluted load (unavailable to depurate). The model yielded a general equation, which can predict the viral load at any depuration time knowing the specific filtration rate, dependent on the bivalve species, and specific viral properties. The mathematical model can be combined with quantitative risk assessment calculations to determine the safety of the depurated shellfish, which can be very helpful not only for shellfish producers but also to public health authorities.