Progress and challenges in thermal inactivation of norovirus in oysters

Norovirus is the leading cause of viral foodborne illnesses worldwide, primarily due to its high infectivity, transmissibility, and environmental persistence. Oysters bioaccumulate norovirus particles through filter-feeding in sewage-contaminated waters and retain them for extended periods. Raw oysters are considered a significant high-risk food commody, as they can serve as vectors to transfer the pathogen to humans. Outbreaks associated with the consumption of cooked oysters indicate survival of virus particles in response to various cooking techniques. Undercooked oysters pose a substantial risk of norovirus infection, a risk that is suggested to be similar to raw oysters. Detecting human norovirus in food remains challenging due to the lack of a quantitative culture-based system that has hindered our understanding of norovirus response to heat. This article provides a critical review of the literature on mechanisms of heat inactivation and potential factors involved in the survival of norovirus in oysters during cooking. It also highlights challenges associated with norovirus detection, the necessity of risk-based research on norovirus in cooked oysters and understanding the impact of the virus-associated matrix on virus inactivation. Addressing these knowledge gaps is crucial for conducting a risk-based approach to determining cooking conditions sufficient to inactivate norovirus oysters to safe levels.