Viruses in Mussels: Public Health Implications and Depuration

Studies were conducted in the common mussel ( Mytilus spp .) to evaluate the public health implications derived from shellfish contamination with human pathogenic enteric viruses. In bioaccumulation experiments, we could verify that after 6 h of immersion of mussels in marine water contaminated with high levels of clay-associated enteric adenovirus (type 40) and human rotavirus (type 3), between 4 to 56% of the seeded viruses were adsorbed to shellfish tissues, mainly in the gills and digestive tract. We investigated the occurrence of wild-type enteric viruses in mussels from sites with different levels of fecal pollution. Pathogenic viruses could be detected in mussels from areas that, following current standards based on bacteriological quality, should be regarded as unpolluted, safe for swimming, and suitable for harvesting shellfish. Cooking experiments performed with contaminated mussels revealed that 5 min after the opening of the mussel valves, rotaviruses and hepatitis A virus could still be recovered in steamed shellfish. Under commercial depuration conditions, health-significant enteric viruses, such as rotavirus and hepatitis A virus, could be recovered from bivalves after 96 h of immersion in a continuous flow of ozonated marine water. Routine screening of bivalves for the presence of health-significant enteric viruses before public consumption may help in the prevention of outbreaks among shellfish consumers.