Viral Pollution of Shellfish in Estuary Waters

Enteroviruses appear in oysters following pollution of estuary waters by waste-treatment plant effluents. Primary treatment, with or without chlorination, and stabilization pond effluents are regular contributors of enterovirus. Increased levels of chlorination accompanied by prolongation of retention time lead to a reduction in the number of viral isolations made from treated effluents. Enterovirus occurs in oysters collected from seawater containing less than 70 Coliform median MPN per 100 ml. Reduction of viral pollutants to undetectable levels in oysters by depuration in estuary waters requires 3 days to 6 days. Depuration efficacy was adversely affected by large numbers of viral pollutants in oysters, by water temperatures falling below 10○ C, or both.