The most effective public health measures to protect consumers from exposure to norovirus in oysters are to produce oysters in areas which are not contaminated or to prevent contamination of mollusc production areas.

And current methods used to remove norovirus in shellfish are not an effective means of reducing contamination.

So says the European Food Safety Authority (EFSA) Panel on Biological Hazards (BIOHAZ Panel) in a new risk assessment.

The Panel recommends establishing acceptable limits for the presence of virus in oysters that are harvested and placed on the market in the European Union. In addition, an EU-wide baseline survey on norovirus in oysters should be carried out to provide information on overall consumer exposure as well as the public health impact of control measures.

Norovirus is transmitted through the consumption of food or water contaminated with fecal matter or through person-to-person contact or contact with infected surfaces. Oysters contaminated with norovirus pose a particular risk to human health as they are often consumed raw.

EFSA’s BIOHAZ Panel concludes that norovirus is highly infectious and that the amount of the virus detected in oysters linked to human cases can vary greatly.

Scientists highlight that norovirus is frequently detected in oysters in Europe which comply with existing EU control standards for bivalve molluscs.