Modelling norovirus dynamics within oysters emphasises potential food safety issues associated with current testing &...

Area of Science:

• Food safety
• Marine microbiology
• Gastroenterology

Background:

• Norovirus is a major cause of viral gastroenteritis globally, frequently associated with raw oyster consumption.
• Current shellfish safety assessments use Escherichia coli as a proxy for norovirus, which is inadequate.
• Existing norovirus assays only detect viruses in oyster digestive tracts, potentially underestimating total viral load.

Purpose of the Study:

• To model norovirus sequestration within oysters, considering both observable and cryptic compartments.
• To determine optimal depuration times for accurate norovirus testing in oysters.
• To inform future norovirus legislation for shellfish safety.

Main Methods:

• Developed a mathematical model incorporating norovirus sequestration into observable and cryptic compartments within oysters.
• Analyzed depuration trial data to validate model predictions.
• Compared model outputs with existing studies on viral decay in shellfish.

Main Results:

• Total norovirus levels in shellfish show peaks during early depuration, influenced by the proportion of cryptic norovirus.
• Viral levels exhibit multiphase decay patterns, consistent with depuration trial data and other studies.
• Identified 62 hours as the recommended depuration time before norovirus testing.

Conclusions:

• Future norovirus legislation must account for total viral load in oysters, not just harvest water quality.
• Current testing methods may not fully represent the norovirus risk associated with oyster consumption.
• Implementing a 62-hour depuration period ensures detection of cryptic norovirus or its clearance, improving shellfish safety standards.