For shellfish, the viral contamination clearly occurs in the first step of the process i.e. in growing and harvesting areas. As opposed to other foods, there is no proof that other routes (foodhandlers, aerosol), could be at the origin of the seafood contamination (Koopmans & Duizer, 2004). Most of the time, untreated sewage are at the origin of the presence of viruses in shellfish. However, direct contamination by ill people working in the growing area, has also been reported (Berg et al., 2000; Butt et al, 2004).