Noroviruses in oysters

Oysters are bivalve molluscs that feed on phytoplankton and other particles by filtering water. Oysters can filter several litres of water per hour. If the water is contaminated by sewage, they may accumulate large amounts of norovirus particles. Since oysters usually are consumed raw, there is no virus inactivation and the probability of contracting illness following consumption is high.

Note: this report is published by the Swedish Food Agency (Livsmedelsverket) as part of their Report Series (www.livsmedelsverket.se/bestall-ladda-ner-material/sok-publikationer/artiklar/2021/l-2021-nr-08-norovirus-i-ostron)